G. Cardini, V. Schettino,
Structure and dynamics of carbon dioxide clusters: A molecular dynamics study,
The Journal of Chemical Physics, 1989, Volume 90, Issue 8, Pages 4441,
DOI: 10.1063/1.456629, https://doi.org/10.1063/1.456629.
Annotation
Molecular dynamics calculations have been used to explore the structure and dynamics of clusters of carbon dioxide, ranging in size up to 164 molecules. The most detailed calculations have been carried out around T=90 K with a view to interpreting the results of infrared data on clusters produced in a seeded argon beam. Under appropriate conditions, in addition to liquid‐like clusters, we have been able to produce clusters with the following structures: (i) an ordered solid—analogous to the bulk crystal, (ii) a bulk–solid core with liquid‐like outer layers, (iii) an amorphous solid, and (iv) an amorphous solid core with liquid‐like outer layers. We have calculated the dispersion of the infrared active intramolecular Q3 mode for these clusters using the transition‐dipole transition‐dipole interaction that is usually invoked to explain the infrared spectrum of the bulk crystal. The resulting spectrum for the Q3 mode of each type of cluster is quite distinct in appearance. This observation suggests that molecular dynamics calculations could be a valuable diagnostic tool in the study of clusters. The dynamical behavior of these clusters has also been investigated, and we find evidence for the existence of large‐amplitude, low‐frequency symmetric breathing modes with frequencies in the range 2–4 cm−1. The overall shape of the experimental Fourier transform infrared spectra of clusters produced in a seeded argon jet is very similar in appearance to the calculated spectrum for a cluster of 116 molecules with an ordered solid core and liquid‐like outer layers.
V. S. Meadows, D. Crisp, Ground-based near-infrared observations of the Venus nightside: The thermal structure and water abundance near the surface,
Journal of Geophysical Research, 1996, Volume 101E, no. 2, Pages 4595-4622,
DOI: 10.1029/95JE03567.
Annotation
We used ground-based near-infrared (NIR) observations of thermal emission from the Venus nightside to determine the temperature structure and water vapor distribution between the surface and the 6-km level. We show that emission from spectral windows near 1.0, 1.1, and 1.18 μm originates primarily from the surface and lowest scale height (∼16 km). These windows include absorption by weak H 2 O and CO 2 lines and by the far wings of lines in strong nearby CO 2 bands. Rayleigh scattering by the 90-bar CO 2 atmosphere and Mie scattering by the H 2 SO 4 clouds attenuate this emission, but add little to its spectral dependence. Surface topography also modulates this NIR thermal emission because high-elevation regions are substantially cooler and emit less thermal radiation than the surrounding plains. These contributions to the emission are clearly resolved in moderate-resolution (λ/Δλ ∼ 400) spectral image cubes of the Venus nightside acquired with the infrared imaging spectrometer (IRIS) on the Anglo-Australian Telescope (AAT) in 1991. To analyze these observations, we used a radiative transfer model that includes all of the radiative processes listed above. Synthetic spectra for several topographic elevations were combined with Pioneer Venus altimetry data to generate spatially resolved maps of the NIR thermal emission. Comparisons between these synthetic radiance maps and the IRIS observations indicate no near-infrared signature of the surface emissivity differences seen at microwave wavelengths by the Magellan orbiter. Assuming constant surface emissivity in the near-infrared, we derive nightside averaged temperature lapse rates of -7 to -7.5 K/km in the lowest 6 km. These lapse rates are smaller and indicate much greater static stability than those inferred from earlier measurements and greenhouse models (-8 to -8.5 K/km) [Seiff 1983]. An acceptable fit to the data was obtained with an H 2 O mixing ratio profile which increases from 20 ppmv at the cloud base to 45 ppmv at 30 km, and then remains constant between that altitude and the surface. There is no evidence for H 2 O mixing ratios that decrease with altitude, like those inferred from the Pioneer Venus large probe mass spectrometer [Donahue and Hodges, 1992a] or the Venera 11 and 12 Lander spectrophotometers [Moroz, 1983].
Y.I. Baranov, A.A. Vigasin,
Collision-Induced Absorption by CO2 in the Region of ν1, 2ν2,
Journal of Molecular Spectroscopy, 1999, Volume 193, Issue 2, Pages 319-325,
DOI: 10.1006/jmsp.1998.7743.
Annotation
Collision-induced absorption (CIA) by CO2 is measured in the 1100–1600 cm−1range using a Fourier-transform spectrometer with a resolution of 0.5 cm−1. The current measurements, which agree well with previous ones but are more precise, reveal pronounced structures on top of both unresolved Fermi doublet bands consisting of P-, Q-,and R-like branches. Assignment of Q-branches at 1284.75 cm−1and 1387.75 cm−1to (CO2)2 dimers seems highly probable. The nature of other peaks observed in CIA and Raman spectra of the CO2 Fermi doublet region is discussed.
Ho, W., Birnbaum, G., Rosenberg, A.,
Far-infrared collision-induced absorption in CO2. I. Temperature dependence,
Journal of Chemical Physics, 1971, Volume 55, Issue 3, Pages 1028,
DOI: 10.1063/1.1676181.
Annotation
Accurate measurements of collisionЃ]induced absorption in CO2 are made at a number of temperatures in the range from − 40 to 60°C in the wavelength region 7–250 cm−1. Direct evidence for the separation of the pure translational band from the rotational–translational band is obtained at all temperatures. This and other aspects of the band shape are discussed. Over the entire temperature range, the experimentally determined Kramers–Kronig integral is found to be in good agreement with the theoretical value, i.e., the static dielectric constant. This agreement is achieved only when the contribution of the quadrupole–quadrupole energy in the radial distribution function, of particular importance for CO2 because of its large quadrupole moment, is calculated accurately. A value of the quadrupole moment is obtained, (4.5 ± 0.2)10−26 esu, which is in satisfactory agreement with that obtained by the method of Buckingham and Disch, which does not depend on a knowledge of intermolecular force constants. Induction due to higher multipole moments and the overlap interaction is considered.
Dagg I.R., Reesor. G.E., and Urbaniak J. , Collision Induced Microwave Absorption in CO2, and CO2-Ar, CO2-CH4 Mixtures in the 2.3 cm-1 Region,
Canadian Journal of Physics, 1974, Volume 52, Issue 11, Pages 973,
DOI: 10.1139/p74-133.
Annotation
Collision induced microwave absorption is reported in pure CO2, and CO2-Ar, CO2-CH4 mixtures in the 70 G H z (2.3 cm-1) region at a temperature of 22°C, using a sensitive cavity technique previously described. The results in pure CO2 in the very low density region from 5 to 30 amagat accurately establish the dependence of the loss on the square and cube of the density, and the relaxation times are calculated. The experimental results agree well with previously reported lower frequency data at 0.3-0.8 cm-1 which establishes the linear dependence on frequency of the absorption up to 2.3 cm-1. There is also good agreement with an extrapolation of higher frequency infrared results of Ho et al. The relaxation times associated with the two and three body collisions are shown to be nearly equal at room temperatures with T~ = 0.84 x 10-12 s and T~ = 1.0 x 10-12 S. Higher order dependence on the density is observed for the CO2-Ar and CO2-CH4 mixtures. The results are compared with earlier low frequency measurements at 0.8 cm-1 and with the theory of Maryott and Kryder, taking account of correction terms in the dielectric virial coefficient according to Bose and Cole.
G. Cardini, V. Schettino,
Structure and dynamics of carbon dioxide clusters: A molecular dynamics study,
The Journal of Chemical Physics, 1989, Volume 90, Issue 8, Pages 4441,
DOI: 10.1063/1.456629, https://doi.org/10.1063/1.456629.
Annotation
Molecular dynamics calculations have been used to explore the structure and dynamics of clusters of carbon dioxide, ranging in size up to 164 molecules. The most detailed calculations have been carried out around T=90 K with a view to interpreting the results of infrared data on clusters produced in a seeded argon beam. Under appropriate conditions, in addition to liquid‐like clusters, we have been able to produce clusters with the following structures: (i) an ordered solid—analogous to the bulk crystal, (ii) a bulk–solid core with liquid‐like outer layers, (iii) an amorphous solid, and (iv) an amorphous solid core with liquid‐like outer layers. We have calculated the dispersion of the infrared active intramolecular Q3 mode for these clusters using the transition‐dipole transition‐dipole interaction that is usually invoked to explain the infrared spectrum of the bulk crystal. The resulting spectrum for the Q3 mode of each type of cluster is quite distinct in appearance. This observation suggests that molecular dynamics calculations could be a valuable diagnostic tool in the study of clusters. The dynamical behavior of these clusters has also been investigated, and we find evidence for the existence of large‐amplitude, low‐frequency symmetric breathing modes with frequencies in the range 2–4 cm−1. The overall shape of the experimental Fourier transform infrared spectra of clusters produced in a seeded argon jet is very similar in appearance to the calculated spectrum for a cluster of 116 molecules with an ordered solid core and liquid‐like outer layers.
Marcin Gruszka, Aleksandra Borysow,
Roto-Translational Collision-Induced Absorption of CO2 for the Atmosphere of Venus at Frequencies from 0 to 250 cm-1, at Temperatures from 200 to 800 K,
Icarus, 1997, Volume 129, Issue 1, Pages 172-177,
DOI: h10.1006/icar.1997.5773, http://dx.doi.org/10.1006/icar.1997.5773.
Annotation
The collision-induced absorption of gaseous CO2is the primary source of far-infrared opacity of the atmosphere of Venus. At the temperatures and densities of the venusian atmosphere, the absorption is due mainly to binary collisions of CO2molecules. Using a realistic anisotropic intermolecular potential and assuming the absorbing dipole to be due to the electrostatic induction and a quantum overlap, a series of molecular dynamics simulations were performed for the temperature range 200 to 800 K, and the roto-translational collision-induced absorption spectra at frequencies from 0 to 250 cm−1were derived. The absorption coefficient in the submillimeter region, used in constituency retrieval studies, decreases more than 10 times in the temperature range 200 to 800 K. On the other hand, the absorption coefficient at 800 K and at the frequency range above 150 cm−1was found to be almost 10 times higher than at 200 K. Earlier works relied on experimental RT CIA data at a fixed temperature of 300 K. The new, temperature-dependent absorption bands may, when included in the analysis of the atmospheric radiative transfer of the planet, help explain the observed high far-infrared opacity of the lower layers of the atmosphere. To make the results of the simulations readily available for atmospheric abundance and radiative transfer analysis, an analytic model of the roto-translational collision-induced absorption spectral profile, applicable from 200 to 800 K, is being proposed here. The FORTRAN computer code of this newly developed model is available from the authors on request.
J.-M. Hartmann, C. Boulet, D. Jacquemart,
Molecular dynamics simulations for CO2 spectra. II. The far infrared collision-induced absorption band,
Journal of Chemical Physics, 2011, Volume 134, Issue 9, Article 094316,
DOI: 10.1063/1.3557681, http://link.aip.org/link/doi/10.1063/1.3557681.
Annotation
Classical molecular dynamics simulations have been carried out for gaseous CO2 starting from various anisotropic intermolecular potential energy surfaces. Through calculations for a large number of molecules treated as rigid rotors, the time evolution of the interaction-induced electric dipole vector is obtained and the Laplace transform of its autocorrelation function gives the collision-induced absorption rototranslational spectrum. The results are successfully compared with those of previous similar calculations before studies of the influences of the intermolecular potential and induced-dipole components are made. The calculated spectra show a significant sensitivity to anisotropic forces consistently with previous analyses limited to the spectral moments. The present results also demonstrate the importance of vibrational and back-induction contributions to the induced dipole. Comparisons between measured far infrared (0–250 cm−1) spectra at different temperatures and results calculated without the use of any adjustable parameter are made. When the best and more complete input data are used, the quality of our predictions is similar to that obtained by Gruszka et al. [Mol. Phys. 93, 1007 (1998)] after the introduction of ad hoc short-range overlap contributions. Our results thus largely obviate the need for such contributions the magnitudes of which remain questioned. Nevertheless, problems remain since, whereas good agreements with measurements are obtained above 50 cm−1, the calculations significantly underestimate the absorption below, a problem which is discussed in terms of various possible error sources.
Ezra Bar‐Ziv, and Shmuel Weiss,
Translational Spectra Due to Collision‐Induced Overlap Moments in Mixtures of He with CO2, N2, CH4, and C2H6,
The Journal of Chemical Physics, 1972, Volume 57, Pages 34.
Annotation
Enhancement of the absorption, upon addition of He to CO2, N2, CH4, and C2H6, has been observed in the frequency region 200–450 cm−1. It is shown that in this frequency region absorption due to multipole moment induction is weak and particularly so because of the very low polarizability of He. The observed spectra are thus due to induction by overlap forces and similar in origin to spectra observed for rare gas mixtures. The observed spectra are indeed found to resemble those for mixtures of He with rare gases in position and shape as well as in intensity. The spectra are analyzed in terms of a hard sphere potential and an overlap moment varying exponentially with intermolecular separation.
L. Mannik, J. C. Stryland,
The ν1 Band of Carbon Dioxide in Pressure-Induced Absorption. II. Density and Temperature Dependence of the Intensity; Critical Phenomena,
Canadian Journal of Physics, 1972, Volume 50, Issue 12, Pages 1355-1362,
DOI: 10.1139/p72-186.
Annotation
The ν1 band of gaseous carbon dioxide has been studied in pressure-induced absorption at temperatures of ~ 190, ~ 300, and ~ 470 K, over a density range from 0.5 to 300 amagat, and with path lengths from 0.007 to 56 m. The observed temperature variation of the binary absorption coefficient can be satisfactorily accounted for only by adding a quadrupole–quadrupole interaction term to the usual Lennard–Jones model for the inter-molecular potential. The band profile is in agreement with the theory of quadrupole-induced absorption. There is some increase in the intensity of the band near the critical point due to the divergence of the correlation length. A very marked increase in the intensity is possibly prevented by the "cancellation effect".
Samples of CO2 at pressures up to 21.3 atm and with paths as long as 1067 m have been employed to measure CO2 absorption between 1100 and 1835 cm-1. Most of the absorption is due to the ν1 and 2ν2 bands. These bands are forbidden for the symmetric 16O12Cl6O and 16O13C16O molecules and, therefore, produce only pressure-induced absorption. The asymmetric 16O12C18O and 16O12C17O molecules produce bands that contain components of both intrinsic and pressure-induced absorption. The integrated-absorption coefficient for the intrinsic absorption is 1.08 × 10-22 (±10%) molecules -l cm2 cm-1. The integrated pressure-induced absorption coefficient is 1.68×10-22 (±8%) molecules-1 cm2 atm-1 cm-l.
Буланин М.О., Булычев В.П., Гранский П.В., Коузов А.П., Тонков М.В.,
Исследование функций пропускания СО2 в области полос 4.3 и 15 мкм,
Проблемы физики атмосферы. Вып. 13, Ленинград, Изд. ЛГУ,
Ленинград, Издательство Ленинградского Государственного Университета, 1976, Pages 14-24.
Induced absorption in carbon dioxide has been studied at a frequency of 9260 Mc/sec over the temperature range 270°—500°K and to pressures as high as 95 atm. Since the dielectric loss ϵ″ is expected on the basis of the dispersion relations to be proportional to frequency throughout the microwave region the data has been fit with an expansion in the amagat density ρ of the form ϵ′′/ = Aρ2+Bρ3, where is in wavenumbers. It is found that A=2.5(1)×10−8(T/273)−3.0(1), and B/A=−1.05(8)×10−2(T/273)−2.3(3). The molecular quadrupole moment calculated from the first coefficient of the dielectric loss A is then 6.7×10−26 (esu).
Кондратьев К.Я., Тимофеев Ю.М.,
Численное моделирование функций пропускания для узких спектральных интервалов 15 мкм полосы СО2,
Известия РАН. Серия Физика атмосферы и океана, 1969, Т. 5, № 4, Страницы 377-387.
Theabsorption of carbon dioxide-nitrogen mixtures at 4.40 µ was examinedover a temperature range of 1200 to 2100°K for opticaldensities of 0.10 to 0.40 atm-cm. The test gas waselevated to desired temperatures by shock compression. Properties of thetest gas were determined by measurement of initial concentrations andshock wave velocities. Absorption was observed as a diminution ofsource beam intensity monitored with a rapid response infrared detectorand displayed on an oscilloscope. Beer's law was found tobe applicable over the range of temperature and concentration studied.Absorption coefficients calculated from Beer's law plots reached a maximumof 3.0 atm—1 cm—1 at about 1400°K, and were independentof total pressure from 0.26 to 1.05 atm. The absorptionwas also measured over a wavelength interval of 4.37 to4.6 µ. The results of this investigation are compared tothe existing theoretical and experimentally determined absorption data.
Москаленко Н.И., Ильин Ю.А.,
Экспериментальные исследования поглощения излучения атмосферными газами при повышенных температурах,
Труды 1 совещания по атмосферной оптике, 1976, Тезисы докладов, часть 1,
Томск, Издательство ИОА, 1976, Страницы 8-12.
Аннотация
Moskalenko N.I., Ilyin Yu.A. Experimental studies of absorption of radiation by atmospheric gases at high temperatures, Proceedings of the 1-st Meeting on Atmospheric Optics, Tomsk, 1976, Abstracts, part 1, pp. 8-12.
Докучаев А.Б., Тонков М.В.,
Определение формы крыльев колебательно-вращательных линий полосы двуокиси углерода,
Оптика и спектроскопия, 1980, Volume 48, Issue 4, Pages 738-744.
Annotation
Dokuchaev A.B., Tonkov M.V., Determination of the shape of the wings of the vibrational-rotational lines of the carbon dioxide band, Optics and Spectroscopy, 1980, Volume 48, Issue 4, Pages 738-744. (Russian version)
V. Robert Stull, Philip J. Wyatt, and Gilbert N. Plass,
The Infrared Transmittance of Carbon Dioxide,
Applied Optics, 1964, Volume 3, Issue 2, Pages 243–254,
DOI: 10.1364/AO.3.000243.
Annotation
The infrared transmittance of carbon dioxide has been calculated over a wide range of path lengths, pressures, and temperatures from 500 to 10,000 cm-1. Values of the transmittance are given at intervals of 2.5 cm-1. In addition, transmittance values are also given which have been averaged over larger intervals. All contributing spectral lines whose relative intensity is greater than 10-8 that of the strongest line in any particular band have been included in the calculation. In addition, the contributions from the eight major isotopic species have been included. The calculation of the vibrational energy levels included terms through the third power of the vibrational quantum number and also the effects of Fermi resonanse. The final transmittance tables were generated using the the quasi-random model of molecular band absorption.
Делер В., Тимофеев Ю.М., Шпенкух Д., Москаленко Н.И.,
Сравнение теоретических и экспериментальных функций пропускания СО2 в области полосы 15 мкм,
Проблемы физики атмосферы. Вып. 13,
Ленинград, Изд-во ЛГУ, 1976, Страницы 24-30.
Аннотация
Deler V., Timofeev Yu.M., Shpenkukh D., Moskalenko N.I.
Comparison of theoretical and experimental CO2 transmission functions in the 15 μm band region,
In the book: Problems of Atmospheric Physics. Issue 13, L., Ed. Leningrad State University, 1976, p. 24-30
A theoretical description of line mixing in the Q branch of an infrared rotation-vibration band is obtaibed in the weak coupling approximation. The description is applied to the case of the ν2 band of CO2 near 667 cm-1. Theoretical absorption profiles are given for selected spectral regions corresponding to representative values of the pressure. A comparision is made between the weak coupling results and the results of a forthcoming dynamical calculation of the absorption band shape.
Howard J. N., Burch D. E., Williams D.,
Infrared transmission of synthetic atmospheres. IV. Application of Theoretical Band Models,
Journal of Optical Society of America, 1956, Volume 46, no. 5, Pages 334-338,
DOI: 10.1364/JOSA.46.000334, https://doi.org/10.1364/JOSA.46.000334.
Annotation
Two types of theoretical models for an absorption band are described and applied to infrared absorption bands of CO2 and H2O. For CO2 , which has a regular fine structure, the so-called Elsasser model, which assumes equally-spaced, equally-intense lines, can be applied. For H2O, which has a highly irregular fine structure, the so-called statistical or Goody model, which assumes random spacings and intensity distribution, is applicable. The individual lines are assumed to have the Lorentz shape in both models. The method of application of these models to the experimentally observed bands is discussed in detail.
The temperature dependence of the high frequency far wings of the self-broadened CO2 lines has been investigated in the 2400–2600-cm-1 spectral region. The temperature dependence of the corrective shape factor X(σ,T) is demonstrated for the first time.
R.A. Parker, M.P. Esplin, R.B. Wattson, M.L. Hoke, L.S. Rothman and W.A.M. Blumberg,
High temperature absorption measurements and modeling of CO2 for the 12 micron window region,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1992, Volume 48, Issue 5, Pages 591-597,
DOI: 10.1016/0022-4073(92)90123-L.
Annotation
High temperature absorption measurements were made for CO2 gas in Local Thermodynamic Equilibrium (LTE) with a hot cell and high resolution interferometer. The experimental data were compared to band-model and line-by-line model transmittance calculations using line parameters from the HITRAN and HITEMP data bases. The line-by-line calculations using HITEMP were in excellent agreement with experimental measurements, while the model calculations using the HITRAN data underpredicted the absorption by approx. 10%.
J. -M. Hartmann, C. Boulet, M. Margottin-Maclou, F. Rachet, B. Khalil, F. Thibault and J. Boissoles,
Simple modelling of Q-branch absorption — I. Theoretical model and application to CO2 and N2O,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1995, Volume 54, Issue 4, Pages 705-722,
DOI: 10.1016/0022-4073(95)00088-3.
Annotation
A simple theoretical approach of Q-branch absorption is developed. It is based on the classical approximation of the rotational distribution and a Strong-Collision-type modelling of line-coupling coefficients. The Q-branch absorption is then represented by a very simple analytical expression which depends on six average parameters; pressure and wave-number dependences are included in the model so that the parameters only depend on the molecular system (active molecule + perturber), band, and temperature. Tests show that, provided effective parameters are used, our model enables very satisfactory predictions of the pressure, temperature, and wavenumber dependences of Q-branch absorption. These effective parameters can be deduced from experimental spectra and no previous knowledge of neither the spectroscopic nor collision parameters is required. This makes the present approach suitable for species (most of those of atmospheric interest) for which no alternative and more accurate approach is yet available.
M. V. Tonkov, J. Boissoles, R. Le Doucen, B. Khalil and F. Thibault,
Q-branch shapes of CO2 spectrum in 15 μm,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1996, Volume 55, Issue 3, Pages 321-334,
DOI: 10.1016/0022-4073(95)00165-4.
Annotation
The shapes of Q-branches in CO2 spectra in the 580–850 cm−1 region for pure gas and mixtures CO2---He and CO2---Ar have been studied at resolutions up to 0.002cm−1. The branch broadening coefficients were measured in the pressure range from a few torr to 50 atm. Those for 11102-02201 Π-Δ transition are different for pressures below and above 5 atm. At higher pressures the branch broadening coefficients are similar for all Q-branches. The observed Q-branch shape transformation is explained by line mixing effects.
Kochel J.-M., Hartmann J.-M., Camy-Peyret C., Rodriges R., Payan S.,
Influence of line mixing on absorption by CO2 Q branches in atmospheric balloon-borne spectra near 13 mm,
Journal of Geophysical Research: Atmospheres, 1997, Volume 102, Issue D11, Pages 12891-12899,
DOI: 10.1029/97JD00405, https://doi.org/10.1029/97JD00405.
Annotation
Line mixing in CO2 Q branches is studied in the 13.2 μm region from balloon-borne atmospheric transmission measurements. Eighty-five spectra were recorded (at 67°N, 22°E) in the 660–960 cm−1 region using a Fourier transform spectrometer with an unapodized resolution (full width at half maximum) of 0.013 cm−1. They involve balloon altitudes and tangent heights from 13 to 30 km and a large range of optical thicknesses. The results of computations assuming Voigt line shapes as well as accounting for line mixing are compared with measured transmissions in three CO2 Q branches of different intensities and symmetries. They confirm the significant effect of line mixing and validate recent line coupling models. As a consequence of the accuracy of the forward approach the Q branches can be used for remote sensing; this should lead to improved precision of pressure/temperature retrievals since absorption in the Q branch wing region is particularly pressure sensitive.
M. V. Tonkov, N. N. Filippov, Yu. M. Timofeyev and A. V. Polyakov,
A simple model of the line mixing effect for atmospheric applications: Theoretical background and comparison with experimental profiles,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1996, Volume 56, Issue 5, Pages 783-795,
DOI: 10.1016/S0022-4073(96)00113-6.
Annotation
We propose a new empirical method of band shape calculations which takes into account line mixing effects. The proposed shape is based on the strong collision model with attenuated interbranch coupling. Apart from the conventional set of spectral line parameters one needs only one additional parameter to account for line mixing effects in band profile calculations. This parameter depends on the perturbing gas type. It is the same for all molecular infrared absorption bands. The new shapes are shown to be successful in representing the measured absorption bands of CO2 in nitrogen (v2, v3, v2 + 2v3, 2v2 − v2, and 2v1 − v2) and the 3.6 μm band of O3 in nitrogen.
Поляков А.В., Тимофеев Ю.М., Тонков М.В., Филиппов Н.Н.,
Влияние интерференции спектральных линий на функции пропукания атмосферы в полосах поглощения СО2,
Известия РАН. Серия Физика атмосферы и океана, 1998, Volume 34, no. 3, Pages 357-367.
Ma, Q., Tipping R.H.,
Extension of the quasistatic far-wing line shape theory to multicomponent anisotropic potentials,
Journal of Chemical Physics, 1994, Volume 100, no. 12, Pages 8720-8736,
DOI: 10.1063/1.466727.
Annotation
The formalism developed previously for the calculation of the far-wing line shape function and the corresponding absorption coefficient using a single-component anisotropic interaction term and the binary collision and quasistatic approximations is generalized to multicomponent anisotropic potential functions. Explicit expressions are presented for several common cases, including the long-range dipole-dipole plus dipole-quadrupole interaction and a linear molecule interacting with a perturber atom. After determining the multicomponent functional representation for the interaction between CO2 and Ar from previous published data, we calculate the theoretical line shape function and the corresponding absorption due to the v3 band of CO2 in the frequency region 2400-2580 cm-1 and compare our results with previous calculations carried out using a single-component anisotropic interaction, and with the results obtained assuming Lorentzian line shapes. The principal uncertainties in the present results, possible refinements of the theoretical formalism, and the applicability to other systems are discussed briefly.
Ma Q. , Tipping R.H.,
An improved quasistatic line shape theory: The effects of molecular motion on the line wing.,
Journal of Chemical Physics, 1994, Volume 100, no. 8, Pages 5567 - 5579,
DOI: 10.1063/1.467124.
Annotation
A theory is presented for the modification of the line-shape functions and absorption coefficient due to the breakdown of the quasistatic approximation. This breakdown arises from the effects of molecular motion and increases the absorption in the near wings. Numerical calculations for the high-frequency wing of the ν3 band of CO2 broadened by Ar are reported and it is shown that these effects are significant near the bandhead. The importance of such. corrections in other spectral regions and for other systems is discussed briefly.
V. S. Meadows, D. Crisp, Ground-based near-infrared observations of the Venus nightside: The thermal structure and water abundance near the surface,
Journal of Geophysical Research, 1996, Volume 101E, no. 2, Pages 4595-4622,
DOI: 10.1029/95JE03567.
Annotation
We used ground-based near-infrared (NIR) observations of thermal emission from the Venus nightside to determine the temperature structure and water vapor distribution between the surface and the 6-km level. We show that emission from spectral windows near 1.0, 1.1, and 1.18 μm originates primarily from the surface and lowest scale height (∼16 km). These windows include absorption by weak H 2 O and CO 2 lines and by the far wings of lines in strong nearby CO 2 bands. Rayleigh scattering by the 90-bar CO 2 atmosphere and Mie scattering by the H 2 SO 4 clouds attenuate this emission, but add little to its spectral dependence. Surface topography also modulates this NIR thermal emission because high-elevation regions are substantially cooler and emit less thermal radiation than the surrounding plains. These contributions to the emission are clearly resolved in moderate-resolution (λ/Δλ ∼ 400) spectral image cubes of the Venus nightside acquired with the infrared imaging spectrometer (IRIS) on the Anglo-Australian Telescope (AAT) in 1991. To analyze these observations, we used a radiative transfer model that includes all of the radiative processes listed above. Synthetic spectra for several topographic elevations were combined with Pioneer Venus altimetry data to generate spatially resolved maps of the NIR thermal emission. Comparisons between these synthetic radiance maps and the IRIS observations indicate no near-infrared signature of the surface emissivity differences seen at microwave wavelengths by the Magellan orbiter. Assuming constant surface emissivity in the near-infrared, we derive nightside averaged temperature lapse rates of -7 to -7.5 K/km in the lowest 6 km. These lapse rates are smaller and indicate much greater static stability than those inferred from earlier measurements and greenhouse models (-8 to -8.5 K/km) [Seiff 1983]. An acceptable fit to the data was obtained with an H 2 O mixing ratio profile which increases from 20 ppmv at the cloud base to 45 ppmv at 30 km, and then remains constant between that altitude and the surface. There is no evidence for H 2 O mixing ratios that decrease with altitude, like those inferred from the Pioneer Venus large probe mass spectrometer [Donahue and Hodges, 1992a] or the Venera 11 and 12 Lander spectrophotometers [Moroz, 1983].
L.I.Nesmelova, O.B.Rodimova, and S. D. Tvorogov,
Absorption coefficient in the infrared CO2 Q-branch,
SPIE . V.1811,
SPIE - The international society for optical engineering, 1992, Pages 295-297.
Annotation
The values of absorption coefficient K in the wings of the infrared CO2 Q-branches significantly differ from those isolated Lorentzian lines. It becomes now traditional to explain these deviations by line-mixing. Actually, presence of the small line separations in the Q-branches are greatly conductive to this point of view. It can be noted, however, that the largest deviations from the Lorentzian line calculations are observed in spectral regions comparatively far from the line centers. Therefore it would be interesting to know whether the line wing theory can be used to describe the observed frequency dependence of K or not.
N. N. Filippov, V. P. Ogibalov and M. V. Tonkov,
Line mixing effect on the pure CO2 absorption in the 15 μm,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2002, Volume 72, Issue 4, Pages 315-325,
DOI: 10.1016/S0022-4073(01)00124-8.
Annotation
The IR absorption of the pure CO2 gas in the region of 15 μm was examined. A special attention was given to the line mixing effect that influences the spectral shape of the vibration–rotation absorption bands in the Q-branch regions. Two methods in shape description were analyzed. The first method uses the Rosenkranz line shapes with the line mixing parameters, which are found from an empirical rotational relaxation matrix. The second method is based on the strong collision model with adjusted branch coupling (ABC-model). The merits and the demerits of these two methods are discussed, and the results of the corresponding calculations are compared to the measured shapes. It is inferred that the ABC-model for the absorption coefficient calculations can be successfully applied for solving the non-LTE radiative transfer problem in CO2 bands in the atmospheres of Earth-like planets.
S.A. Tashkun, V. I. Perevalov, J-L. Teffo, A. D. Bykov and N. N. Lavrentieva,
CDSD-1000, the high-temperature carbon dioxide spectroscopic databank,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2003, Volume 82, Issue 1, Pages 165-196,
DOI: 10.1016/S0022-4073(03)00152-3.
Annotation
We present a high-temperature version, CDSD-1000, of the carbon dioxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air-broadened half-widths) of the four most abundant isotopic species of the carbon dioxide molecule. The reference temperature is Tref=1000°K and the intensity cutoff is Icut=10−27 cm−1/moleculecm−2. More than 3 million lines covering the 260–8310, 418–2454, 394–4662, and 429–2846 cm−1 spectral ranges for 12C16O2, 13C16O2, 12C16O18O, and 12C16O17O, respectively, are included in CDSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonians and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulations of several low- and medium-resolution high-temperature (T=800-3000 K) spectra have been performed in order to validate the databank. Comparisons of CDSD-1000 with other high-temperature databanks HITEMP, HITELOR, and EM2C are also given. CDSD-1000 is able to reproduce observed spectra in a more satisfactory way than the high-resolution databank HITEMP for temperatures higher than 1000°K. The databank is useful for studying high-temperature radiative properties of CO2. CDSD-1000 is freely accessible via the Internet.
F. Niro, C. Boulet, J.-M. Hartmann,
Spectra calculations in central and wing regions of CO2 IR bands between 10 and 20 μm. I: model and laboratory measurements,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2004, Volume 88, Pages 483–498,
DOI: doi:10.1016/j.jqsrt.2004.04.003.
Annotation
Temperature (200–300 K) and pressure (70–200 atm) dependent laboratory measurements of infrared transmission by CO2–N2 mixtures have been made. From these experiments the absorption coefficient is reconstructed, over a range of several orders of magnitude, between 600 and 1000 cm-1. The elevated densities used in the experiments (up to 200 atm) magnify the contribution of the wings of the v2 band lines. In order to analyze the spectra, a theoretical model based on the energy corrected sudden approximation is proposed which accounts for line-mixing effects within the impact approximation. This approach uses the model and associated parameters built previously to model Q branches (JQSRT 1999;61:153) but extends it by nowincluding all P, Q, and R lines. No adjustable parameters are used and fundamental properties of the collisional relaxation operator are verified by using a renormalization procedure. Comparisons between measured and calculated spectra confirm that neglecting line-mixing (Lorentzian model) leads to an overestimation of absorption by up to three orders of magnitude in the far wings. On the other hand, the proposed approach leads to satisfactory results both in regions dominated by contributions of local lines and in the wing: measured spectra are correctly modeled over a range where absorption varies by more than four orders of magnitude. The largest discrepancies, which appear about 150 cm-1 from the v2 center, can be due to finite duration of collisions effects or to uncertainties in the experimental determination of very weak absorption.
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
Collision-induced absorption is of great importance to the overall radiative budget in dense CO2-rich atmospheres, but its representation in climate models remains uncertain, mainly due to a lack of accurate experimental and theoretical data. Here we compare several parameterisations of the effect, including a new one that makes use of previously unused measurements in the 1200–1800 cm−1 spectral range. We find that a widely used parameterisation strongly overestimates absorption in pure CO2 atmospheres compared to later results, and propose a new approach that we believe is the most accurate possible given currently available data.
F. Niro, F. Hase, C. Camy-Peyret, S. Payan, J. -M. Hartmann,
Spectra calculations in central and wing regions of CO2 IR bands between 10 and 20 μm. II. Atmospheric solar occultation spectra,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2005, Volume 90, Issue 1, Pages 43-59,
DOI: 10.1016/j.jqsrt.2004.04.004.
Annotation
The theoretical approach based on the Energy Corrected Sudden Approximation presented in the previous companion paper is used in order to account for line-mixing effects in infrared bands of CO2. Its performance, which was demonstrated using laboratory spectra is confirmed here by considering atmospheric transmission in the 10–14 μm region. Comparisons are made between forward calculations of atmospheric transmission spectra and values measured using two different solar occultation experiments based on high resolution Fourier transform instruments. The results demonstrate that neglecting line-mixing and using a Voigt model can lead to a very large overestimation of absorption that may extend over more than 300 cm−1 in the wing of the CO2 ν2 band. They also demonstrate the capability of our model to represent accurately the absorption in the entire region for a variety of atmospheric paths. Among positive consequences of the quality of the model, the possibility of retrieving amounts of (heavy) trace gases with weak and broad absorption features is demonstrated.
Bharadwaj S.P., Modest M.F.,
Medium resolution transmission measurements of CO2 at high temperature – an update,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2007, Volume 103, Pages 146-155,
DOI: 10.1016/j.jqsrt.2006.05.011, https://doi.org/10.1016/j.jqsrt.2006.05.011.
Annotation
The current work presents updated measurements of narrow-band transmission for the 2.0, 2.7 and 4.3 μm bands of CO2 at temperatures of up to 1550 K. In addition, measurements for 15 μm the band of CO2 are also presented for the first time. Data were collected with an improved drop tube design (as compared to the earlier measurements) and an FTIR-spectrometer. The measured data were compared with the CDSD and HITEMP databases, as well as with previous data obtained from the old drop tube apparatus. The new data have less uncertainties at extreme temperatures than the old data and eliminate some of the problems associated with subtraction of the emission signal with the old apparatus. The data show minor discrepancies with the high-resolution databases, particularly with HITEMP at higher temperatures, but in general agreement is good.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Ruslan E. Asfin, Jeanna V. Buldyreva, Tatyana N. Sinyakova, Daniil V. Oparin, Nikolai N. Filippov,
Evidence of stable van der Waals CO2 clusters relevant to Venus atmosphere conditions,
Journal of Chemical Physics, 2015, Volume 142, Issue 5, Article 051101,
DOI: 10.1063/1.4906874.
Annotation
Non-intrusive spectroscopic probing of weakly bound van der Waals complexes forming in gaseous carbon dioxide is generally performed at low pressures, for instance in supersonic jets, where the low temperature favors dimers, or in few-atmosphere samples, where the signature of dimers varying as the squared gas density is entangled with the dominating collision-induced absorption. We report experimental and theoretical results on CO2 dimers at very high pressures approaching the liquid phase. We observe that the shape of the CO2 -dimer bands undergoes a distinctive line-mixing transformation, which reveals an unexpected stability of the dimers despite the collisions with the surrounding particles and negates the common belief that CO2 dimers are short-lived complexes. Our results furnish a deeper insight allowing a better modeling of CO2 -rich atmospheres and provide also a new spectroscopic tool for studying the robustness of molecular clusters.
Yu.I. Baranov,
On the significant enhancement of the continuum-collision induced absorption in H2O+CO2 mixtures,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2016, Volume 175, Pages 100-106,
DOI: 10.1016/j.jqsrt.2016.02.017, https://doi.org/10.1016/j.jqsrt.2016.02.017.
Annotation
The IR spectra of water vapor–carbon dioxide mixtures as well as the spectra of pure gas samples have been recorded using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm−1 in order to explore the effect of colliding CO2 and H2O molecules on their continuum absorptions. The sample temperatures were 294°, 311°, 325° and 339°K. Measurements have been conducted at several different water vapor partial pressures depending on the cell temperature. Carbon dioxide pressures were kept close to the three values of 103, 207 and 311 kPa (1.02, 2.04 and 3.07 atm). The path length used in the study was 100 m. It was established that, in the region around 1100 cm−1, the continuum absorption coefficient CH2O+CO2 is about 20 times stronger than the water–nitrogen continuum absorption coefficient CH2O+N2. On the other hand, in the far wing region (2500 cm−1) of the ν3 CO2 fundamental band, the binary absorption coefficient CCO2+H2O appears to be about one order of magnitude stronger than the absorption coefficient in CCO2+CO2 pure carbon dioxide. The continuum interpretation and the main problem of molecular band shape formation are discussed in light of these experimental facts.
T. E. Klimeshina, T. M. Petrova, O. B. Rodimova, A. A. Solodov, A. M. Solodov,
CO2 absorption in band wings in near IR,
Atmospheric and Oceanic Optics, 2015, Volume 28, Issue 5, Pages 387–393,
DOI: 10.1134/S1024856015050073, https://doi.org/10.1134/S1024856015050073.
Annotation
The CO2 absorption was measured in the 7000 and 8000 cm–1 regions. The absorption coefficients were calculated using the asymptotic line wing shape theory. Line shape parameters were found from fitting to experimental data. The calculation results agree well with the measurement data. According to the line wing theory, the absorption in the band wings is caused by the wings of strong lines of an adjacent band. Within these assumptions, experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7000 and 8000 cm–1 regions can provide information on the line shape at frequency detuning from several tens to several hundreds of half-widths. The results support the hypothesis that line shape parameters in the line wings related to transitions with the same initial state are close to each other. Deviations from a Lorentzian profile are found for some CO2 bands and turn out different for the wings of different bands
Daniil V. Oparin, Nikolai N. Filippov, Ivan M. Grigoriev, Alexander P. Kouzov,
Non-empirical calculations of rotovibrational band wings: Carbon dioxide–rare gas mixtures,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2020, Volume 247, Article 106950,
DOI: 10.1016/j.jqsrt.2020.106950., https://doi.org/10.1016/j.jqsrt.2020.106950..
Annotation
We consider spectral characteristics of rotational perturbation for CO2-Rg collisions (Rg = Ar, Xe) using molecular torques time correlation function and three-dimensional classical trajectories without several conventionally used simplifications. The results are applied to the band wing calculation. The calculated wing profiles depend on the potential energy surface and agree well with the experimental data. The relative contributions of collision-induced absorption and the role of dimer absorption are discussed.
(https://www.sciencedirect.com/science/article/pii/S0022407319309537)
Y.I. Baranov, A.A. Vigasin,
Collision-Induced Absorption by CO2 in the Region of ν1, 2ν2,
Journal of Molecular Spectroscopy, 1999, Volume 193, Issue 2, Pages 319-325,
DOI: 10.1006/jmsp.1998.7743.
Annotation
Collision-induced absorption (CIA) by CO2 is measured in the 1100–1600 cm−1range using a Fourier-transform spectrometer with a resolution of 0.5 cm−1. The current measurements, which agree well with previous ones but are more precise, reveal pronounced structures on top of both unresolved Fermi doublet bands consisting of P-, Q-,and R-like branches. Assignment of Q-branches at 1284.75 cm−1and 1387.75 cm−1to (CO2)2 dimers seems highly probable. The nature of other peaks observed in CIA and Raman spectra of the CO2 Fermi doublet region is discussed.
L. Mannik, J. C. Stryland, H. L. Welsh,
An Infrared Spectrum of CO2 Dimers in the "Locked" Configuration,
Canadian Journal of Physics, 1971, Volume 49, Issue 23, Pages 3056-3057,
DOI: 10.1139/p71-364.
Annotation
The two components of the (ν1, 2ν2) Fermi doublet of gaseous CO2 in an absorption path length of 56 m at 192 °K show a complex structure. When the allowed C16O18O absorption and the pressure-induced CO2 absorption are removed by computational procedures, the residual spectrum consists of two similar symmetric patterns of five maxima. These are interpreted in terms of the rotation and vibration of (CO2)2 dimers held by quadrupole–quadrupole interaction in the locked T position at an intermolecular distance of 4.1 Å.
Vigasin A.A., Baranov Y.I., Chlenova G.V.,
Temperature Variations of the Interaction Induced Absorption of CO2 in the ν1, 2ν2 Region: FTIR Measurements and Dimer Contribution,
Journal of Molecular Spectroscopy, 2002, Volume 213, no. 1, Pages 51-56,
DOI: 10.1006/jmsp.2002.8529.
Annotation
The temperature variations in collision-induced absorption (CIA) spectra of carbon dioxide in the region of the Fermi doublet are examined. New FTIR CIA spectra are recorded in the temperature range T=206–296°K. The spectra were subject to decomposition in order to separate true dimer contributions to the CIA profile from the base absorption caused by unbound pairs. The use of statistical physics theory allowed for quite nice reproduction of the observed temperature variations of the normalized dimer intensity.
M. Isabel Cabaço, S. Longelin, Y. Danten, and M. Besnard, Transient dimer formation in supercritical carbon dioxide as seen from Raman scattering,
Journal of Chemical Physics, 2008, Volume 128, Issue 7, Article 074507,
DOI: 10.1063/1.2833493, http://dx.doi.org/10.1063/1.2833493.
Annotation
The polarized and depolarized Raman profiles of supercritical CO2 have been measured in the region of the ν2 bending mode (forbidden transition at about 668 cm−1) and for the Fermi dyad (1285 and 1388 cm−1) along the isotherms 307, 309, 313, and 323 K in a reduced density domain 0.04<ρ* = ρ/ρC<2.04 (ρC ∼ 467.6 kg m−3, ρC is the critical density). The spectral features associated with the ν2 mode (degeneracy removal of the mode and Raman intensity activation) are found to be due to the formation of transient complexes. This is supported by the spectral signatures predicted for parallel slipped dimer and trimers (cyclic and noncyclic) from ab initio calculations taking into account the frequency anharmonicity. The band-shape analysis of the Fermi doublet (observed in the spectral range of 1260–1400 cm−1) shows that on the subpicosecond time scale of the Raman spectroscopy, a tagged CO2 molecule probed two kinds of environment in its first shell of neighbors independent of local density enhancement phenomenon. The first one involves interactions of CO2 with surrounding molecules in the first shell whereas the latter is associated with a transient dimer formation. Finally, a broad band observed between the Fermi dyad (at about 1335 cm−1) is assessed from symmetry considerations and from its depolarization ratio as a further evidence of transient complex formation in supercritical CO2.
A.A. Vigasin,
Intensity and Bandshapes of Collision-Induced Absorption by CO2 in the Region of the Fermi Doublet,
Journal of Molecular Spectroscopy, 2000, Volume 200, Issue 1, Pages 89-95,
DOI: 10.1006/jmsp.1999.8022.
Annotation
The carbon dioxide dimer spectroscopic patterns are retrieved from the analysis of collision-induced absorption (CIA) spectral bandshape at room temperature. It is shown that the use of the simplified model based on the symmetric-top approximation allows roughly consistent simulation of the observed (CO2)2 dimer spectrum. The rotational constants obtained can be considered as effective thermally averaged constants which characterize dimeric structure, strongly distorted from the ground state. The overall CIA bandshape and the integrated intensity of absorption are broken down into partial contributions from tightly bound and metastable dimers and free-pair states. This approach is shown to be in agreement with a wide range of independent spectroscopic and thermodynamic data.
L. Mannik, J. C. Stryland,
The ν1 Band of Carbon Dioxide in Pressure-Induced Absorption. II. Density and Temperature Dependence of the Intensity; Critical Phenomena,
Canadian Journal of Physics, 1972, Volume 50, Issue 12, Pages 1355-1362,
DOI: 10.1139/p72-186.
Annotation
The ν1 band of gaseous carbon dioxide has been studied in pressure-induced absorption at temperatures of ~ 190, ~ 300, and ~ 470 K, over a density range from 0.5 to 300 amagat, and with path lengths from 0.007 to 56 m. The observed temperature variation of the binary absorption coefficient can be satisfactorily accounted for only by adding a quadrupole–quadrupole interaction term to the usual Lennard–Jones model for the inter-molecular potential. The band profile is in agreement with the theory of quadrupole-induced absorption. There is some increase in the intensity of the band near the critical point due to the divergence of the correlation length. A very marked increase in the intensity is possibly prevented by the "cancellation effect".
Samples of CO2 at pressures up to 21.3 atm and with paths as long as 1067 m have been employed to measure CO2 absorption between 1100 and 1835 cm-1. Most of the absorption is due to the ν1 and 2ν2 bands. These bands are forbidden for the symmetric 16O12Cl6O and 16O13C16O molecules and, therefore, produce only pressure-induced absorption. The asymmetric 16O12C18O and 16O12C17O molecules produce bands that contain components of both intrinsic and pressure-induced absorption. The integrated-absorption coefficient for the intrinsic absorption is 1.08 × 10-22 (±10%) molecules -l cm2 cm-1. The integrated pressure-induced absorption coefficient is 1.68×10-22 (±8%) molecules-1 cm2 atm-1 cm-l.
J. -M. Hartmann, C. Boulet, M. Margottin-Maclou, F. Rachet, B. Khalil, F. Thibault and J. Boissoles,
Simple modelling of Q-branch absorption — I. Theoretical model and application to CO2 and N2O,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1995, Volume 54, Issue 4, Pages 705-722,
DOI: 10.1016/0022-4073(95)00088-3.
Annotation
A simple theoretical approach of Q-branch absorption is developed. It is based on the classical approximation of the rotational distribution and a Strong-Collision-type modelling of line-coupling coefficients. The Q-branch absorption is then represented by a very simple analytical expression which depends on six average parameters; pressure and wave-number dependences are included in the model so that the parameters only depend on the molecular system (active molecule + perturber), band, and temperature. Tests show that, provided effective parameters are used, our model enables very satisfactory predictions of the pressure, temperature, and wavenumber dependences of Q-branch absorption. These effective parameters can be deduced from experimental spectra and no previous knowledge of neither the spectroscopic nor collision parameters is required. This makes the present approach suitable for species (most of those of atmospheric interest) for which no alternative and more accurate approach is yet available.
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
Collision-induced absorption is of great importance to the overall radiative budget in dense CO2-rich atmospheres, but its representation in climate models remains uncertain, mainly due to a lack of accurate experimental and theoretical data. Here we compare several parameterisations of the effect, including a new one that makes use of previously unused measurements in the 1200–1800 cm−1 spectral range. We find that a widely used parameterisation strongly overestimates absorption in pure CO2 atmospheres compared to later results, and propose a new approach that we believe is the most accurate possible given currently available data.
Bharadwaj S.P., Modest M.F.,
Medium resolution transmission measurements of CO2 at high temperature – an update,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2007, Volume 103, Pages 146-155,
DOI: 10.1016/j.jqsrt.2006.05.011, https://doi.org/10.1016/j.jqsrt.2006.05.011.
Annotation
The current work presents updated measurements of narrow-band transmission for the 2.0, 2.7 and 4.3 μm bands of CO2 at temperatures of up to 1550 K. In addition, measurements for 15 μm the band of CO2 are also presented for the first time. Data were collected with an improved drop tube design (as compared to the earlier measurements) and an FTIR-spectrometer. The measured data were compared with the CDSD and HITEMP databases, as well as with previous data obtained from the old drop tube apparatus. The new data have less uncertainties at extreme temperatures than the old data and eliminate some of the problems associated with subtraction of the emission signal with the old apparatus. The data show minor discrepancies with the high-resolution databases, particularly with HITEMP at higher temperatures, but in general agreement is good.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Ruslan E. Asfin, Jeanna V. Buldyreva, Tatyana N. Sinyakova, Daniil V. Oparin, Nikolai N. Filippov,
Evidence of stable van der Waals CO2 clusters relevant to Venus atmosphere conditions,
Journal of Chemical Physics, 2015, Volume 142, Issue 5, Article 051101,
DOI: 10.1063/1.4906874.
Annotation
Non-intrusive spectroscopic probing of weakly bound van der Waals complexes forming in gaseous carbon dioxide is generally performed at low pressures, for instance in supersonic jets, where the low temperature favors dimers, or in few-atmosphere samples, where the signature of dimers varying as the squared gas density is entangled with the dominating collision-induced absorption. We report experimental and theoretical results on CO2 dimers at very high pressures approaching the liquid phase. We observe that the shape of the CO2 -dimer bands undergoes a distinctive line-mixing transformation, which reveals an unexpected stability of the dimers despite the collisions with the surrounding particles and negates the common belief that CO2 dimers are short-lived complexes. Our results furnish a deeper insight allowing a better modeling of CO2 -rich atmospheres and provide also a new spectroscopic tool for studying the robustness of molecular clusters.
Yu.I. Baranov,
On the significant enhancement of the continuum-collision induced absorption in H2O+CO2 mixtures,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2016, Volume 175, Pages 100-106,
DOI: 10.1016/j.jqsrt.2016.02.017, https://doi.org/10.1016/j.jqsrt.2016.02.017.
Annotation
The IR spectra of water vapor–carbon dioxide mixtures as well as the spectra of pure gas samples have been recorded using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm−1 in order to explore the effect of colliding CO2 and H2O molecules on their continuum absorptions. The sample temperatures were 294°, 311°, 325° and 339°K. Measurements have been conducted at several different water vapor partial pressures depending on the cell temperature. Carbon dioxide pressures were kept close to the three values of 103, 207 and 311 kPa (1.02, 2.04 and 3.07 atm). The path length used in the study was 100 m. It was established that, in the region around 1100 cm−1, the continuum absorption coefficient CH2O+CO2 is about 20 times stronger than the water–nitrogen continuum absorption coefficient CH2O+N2. On the other hand, in the far wing region (2500 cm−1) of the ν3 CO2 fundamental band, the binary absorption coefficient CCO2+H2O appears to be about one order of magnitude stronger than the absorption coefficient in CCO2+CO2 pure carbon dioxide. The continuum interpretation and the main problem of molecular band shape formation are discussed in light of these experimental facts.
T. E. Klimeshina, T. M. Petrova, O. B. Rodimova, A. A. Solodov, A. M. Solodov,
CO2 absorption in band wings in near IR,
Atmospheric and Oceanic Optics, 2015, Volume 28, Issue 5, Pages 387–393,
DOI: 10.1134/S1024856015050073, https://doi.org/10.1134/S1024856015050073.
Annotation
The CO2 absorption was measured in the 7000 and 8000 cm–1 regions. The absorption coefficients were calculated using the asymptotic line wing shape theory. Line shape parameters were found from fitting to experimental data. The calculation results agree well with the measurement data. According to the line wing theory, the absorption in the band wings is caused by the wings of strong lines of an adjacent band. Within these assumptions, experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7000 and 8000 cm–1 regions can provide information on the line shape at frequency detuning from several tens to several hundreds of half-widths. The results support the hypothesis that line shape parameters in the line wings related to transitions with the same initial state are close to each other. Deviations from a Lorentzian profile are found for some CO2 bands and turn out different for the wings of different bands
Y.I. Baranov, A.A. Vigasin,
Collision-Induced Absorption by CO2 in the Region of ν1, 2ν2,
Journal of Molecular Spectroscopy, 1999, Volume 193, Issue 2, Pages 319-325,
DOI: 10.1006/jmsp.1998.7743.
Annotation
Collision-induced absorption (CIA) by CO2 is measured in the 1100–1600 cm−1range using a Fourier-transform spectrometer with a resolution of 0.5 cm−1. The current measurements, which agree well with previous ones but are more precise, reveal pronounced structures on top of both unresolved Fermi doublet bands consisting of P-, Q-,and R-like branches. Assignment of Q-branches at 1284.75 cm−1and 1387.75 cm−1to (CO2)2 dimers seems highly probable. The nature of other peaks observed in CIA and Raman spectra of the CO2 Fermi doublet region is discussed.
L. Mannik, J. C. Stryland, H. L. Welsh,
An Infrared Spectrum of CO2 Dimers in the "Locked" Configuration,
Canadian Journal of Physics, 1971, Volume 49, Issue 23, Pages 3056-3057,
DOI: 10.1139/p71-364.
Annotation
The two components of the (ν1, 2ν2) Fermi doublet of gaseous CO2 in an absorption path length of 56 m at 192 °K show a complex structure. When the allowed C16O18O absorption and the pressure-induced CO2 absorption are removed by computational procedures, the residual spectrum consists of two similar symmetric patterns of five maxima. These are interpreted in terms of the rotation and vibration of (CO2)2 dimers held by quadrupole–quadrupole interaction in the locked T position at an intermolecular distance of 4.1 Å.
A.A. Vigasin,
Intensity and Bandshapes of Collision-Induced Absorption by CO2 in the Region of the Fermi Doublet,
Journal of Molecular Spectroscopy, 2000, Volume 200, Issue 1, Pages 89-95,
DOI: 10.1006/jmsp.1999.8022.
Annotation
The carbon dioxide dimer spectroscopic patterns are retrieved from the analysis of collision-induced absorption (CIA) spectral bandshape at room temperature. It is shown that the use of the simplified model based on the symmetric-top approximation allows roughly consistent simulation of the observed (CO2)2 dimer spectrum. The rotational constants obtained can be considered as effective thermally averaged constants which characterize dimeric structure, strongly distorted from the ground state. The overall CIA bandshape and the integrated intensity of absorption are broken down into partial contributions from tightly bound and metastable dimers and free-pair states. This approach is shown to be in agreement with a wide range of independent spectroscopic and thermodynamic data.
L. Mannik, J. C. Stryland,
The ν1 Band of Carbon Dioxide in Pressure-Induced Absorption. II. Density and Temperature Dependence of the Intensity; Critical Phenomena,
Canadian Journal of Physics, 1972, Volume 50, Issue 12, Pages 1355-1362,
DOI: 10.1139/p72-186.
Annotation
The ν1 band of gaseous carbon dioxide has been studied in pressure-induced absorption at temperatures of ~ 190, ~ 300, and ~ 470 K, over a density range from 0.5 to 300 amagat, and with path lengths from 0.007 to 56 m. The observed temperature variation of the binary absorption coefficient can be satisfactorily accounted for only by adding a quadrupole–quadrupole interaction term to the usual Lennard–Jones model for the inter-molecular potential. The band profile is in agreement with the theory of quadrupole-induced absorption. There is some increase in the intensity of the band near the critical point due to the divergence of the correlation length. A very marked increase in the intensity is possibly prevented by the "cancellation effect".
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
Collision-induced absorption is of great importance to the overall radiative budget in dense CO2-rich atmospheres, but its representation in climate models remains uncertain, mainly due to a lack of accurate experimental and theoretical data. Here we compare several parameterisations of the effect, including a new one that makes use of previously unused measurements in the 1200–1800 cm−1 spectral range. We find that a widely used parameterisation strongly overestimates absorption in pure CO2 atmospheres compared to later results, and propose a new approach that we believe is the most accurate possible given currently available data.
Bharadwaj S.P., Modest M.F.,
Medium resolution transmission measurements of CO2 at high temperature – an update,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2007, Volume 103, Pages 146-155,
DOI: 10.1016/j.jqsrt.2006.05.011, https://doi.org/10.1016/j.jqsrt.2006.05.011.
Annotation
The current work presents updated measurements of narrow-band transmission for the 2.0, 2.7 and 4.3 μm bands of CO2 at temperatures of up to 1550 K. In addition, measurements for 15 μm the band of CO2 are also presented for the first time. Data were collected with an improved drop tube design (as compared to the earlier measurements) and an FTIR-spectrometer. The measured data were compared with the CDSD and HITEMP databases, as well as with previous data obtained from the old drop tube apparatus. The new data have less uncertainties at extreme temperatures than the old data and eliminate some of the problems associated with subtraction of the emission signal with the old apparatus. The data show minor discrepancies with the high-resolution databases, particularly with HITEMP at higher temperatures, but in general agreement is good.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Ruslan E. Asfin, Jeanna V. Buldyreva, Tatyana N. Sinyakova, Daniil V. Oparin, Nikolai N. Filippov,
Evidence of stable van der Waals CO2 clusters relevant to Venus atmosphere conditions,
Journal of Chemical Physics, 2015, Volume 142, Issue 5, Article 051101,
DOI: 10.1063/1.4906874.
Annotation
Non-intrusive spectroscopic probing of weakly bound van der Waals complexes forming in gaseous carbon dioxide is generally performed at low pressures, for instance in supersonic jets, where the low temperature favors dimers, or in few-atmosphere samples, where the signature of dimers varying as the squared gas density is entangled with the dominating collision-induced absorption. We report experimental and theoretical results on CO2 dimers at very high pressures approaching the liquid phase. We observe that the shape of the CO2 -dimer bands undergoes a distinctive line-mixing transformation, which reveals an unexpected stability of the dimers despite the collisions with the surrounding particles and negates the common belief that CO2 dimers are short-lived complexes. Our results furnish a deeper insight allowing a better modeling of CO2 -rich atmospheres and provide also a new spectroscopic tool for studying the robustness of molecular clusters.
T. E. Klimeshina, T. M. Petrova, O. B. Rodimova, A. A. Solodov, A. M. Solodov,
CO2 absorption in band wings in near IR,
Atmospheric and Oceanic Optics, 2015, Volume 28, Issue 5, Pages 387–393,
DOI: 10.1134/S1024856015050073, https://doi.org/10.1134/S1024856015050073.
Annotation
The CO2 absorption was measured in the 7000 and 8000 cm–1 regions. The absorption coefficients were calculated using the asymptotic line wing shape theory. Line shape parameters were found from fitting to experimental data. The calculation results agree well with the measurement data. According to the line wing theory, the absorption in the band wings is caused by the wings of strong lines of an adjacent band. Within these assumptions, experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7000 and 8000 cm–1 regions can provide information on the line shape at frequency detuning from several tens to several hundreds of half-widths. The results support the hypothesis that line shape parameters in the line wings related to transitions with the same initial state are close to each other. Deviations from a Lorentzian profile are found for some CO2 bands and turn out different for the wings of different bands
Baranov, G.T. Fraser, W.J. Lafferty, A.A.Vigasin
, Collision-induced Absorption in the CO2 Fermi Triad for Temperatures from 211K to 296K, Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere, Editor(s) CLAUDE CAMY-PEYRET and ANDREI A.VIGASIN,
Dordrecht, Kluwer Academic Publishers, 2003, Pages 149-158.
Annotation
Absorption spectra of pure CO2 have been recorded in the vicinity of the 2675 cm−1 Fermi triad for temperatures between 211 K and 296 K. The 2ν1, ν1 + 2ν2, 2ν2 collision-induced components have been extracted from the measured spectra, including for the low frequency band at 2547 cm−1, which is strongly masked by the ν3 wing absorption. Dimeric features are clearly seen on top of the structureless profiles. Integrated intensities of the Fermi-triad components are determined as a function of temperature.
Зуев В.Е., Несмелова Л.И., Творогов С.Д., Фомин В.В.,
Теория крыльев спектральных линий и ее связь с проблемой поглощения и излучения света атмосферными газами,
Томск, Издательство ИОА СО РАН, 1976, 26 Pages.
Annotation
препринт №18
В конспективной форме изложены основы теории формированния периферийной части спектральных линий колебательно-врашательных полос газов. Полное обсуждение проблемы содержится в монографии авторов "Спектроскопия крыльев линий" (издательство "Наука". 1977г. ). В препринте дана сводка некоторых результетов численных расчетов поглощения в крыльях атмосферных газов и описан алгоритм практических вычислений коэффициентов поглощения и излучения. Препринт рассчитан на специалистов по молекулярной спектроскопии, а также занимающихся вопросами оптики и спектроскопии атмосферы Земли и планет.
Zuev V.E., Nesmelova L.I., Tvorogov S.D., Fomin V.V., The theory of wings of spectral lines and its connection with the problem of absorption and emission of light by atmospheric gases, Tomsk, Publishing house of IAO SB RAS, 1976, 26 Pages, Preprint no.18.
In this paper we present the first accurate determination, from laboratory measurements, of the temperature dependence of CO2 continuous absorption beyond the v3 band head, with N2 and O2 as perturbers. The χ form factors previously published have been tested and optimized, and new form factors are proposed. It has been clearly demonstrated for N2, as well as for O2 broadening, that a χ factor independent of T in the range 193 ≤ T ≤ 300 K gives calculated values of the absorption coefficient in fair agreement (±20% level) with observed values in the spectral region 2400 < σ < 2500 cm-1.
The temperature dependence of the high frequency far wings of the self-broadened CO2 lines has been investigated in the 2400–2600-cm-1 spectral region. The temperature dependence of the corrective shape factor X(σ,T) is demonstrated for the first time.
The absolute intensities and air-broadening coefficients, together with their temperature dependence have been determined for a series of very high-J R lines in the ν3 band of CO2 located in the spectral region of some Advanced Moisture and Temperature Sounder (AMTS) channels. These channels are located in the transmission microwindows limited by these lines. The temperature dependence of the absorption coefficient in these microwindows has been measured for N2 and O2 broadening. It has been clearly demonstrated that a correcting shape factor χ(σ) independent of T cannot provide a good agreement between observed and calculated absorption in the range 193 K ≤ T ≤ 300 K for the spectral region of the AMTS channels.
C. Cousin, R. Le Doucen, C. Boulet, A. Henry and D. Robert,
Line coupling in the temperature and frequency dependences of absorption in the microwindows of the 4.3 μm CO2 band,
Journal of Quantitative Spectroscopy and Radiative Transfer, 1986, Volume 36, Issue 6, Pages 521-538,
DOI: 10.1016/0022-4073(86)90125-1.
Annotation
The shapes of the self- and N2-broadened ν3 CO2 fundamental vibration-rotation band in the microwindows (troughs between the lines) have been measured at various temperatures. Important deviations with respect to the superposition of Lorentzian profiles are observed. These deviations are interpreted in terms of line coupling, which redistributes the intensity in the whole band. In order to take into account this line coupling, two models are considered within the frame of the impact theory. The first model uses the strong-collision approximation to describe the rotational energy transferred by collisions. It leads to a simple analytical expression for the band profile. The second model is based on the exponential-gap law. These two models account well for the frequency dependence of the measured absorption in the microwindows and for the temperature dependence in the case of the N2-broadened CO2 band but not in the self-broadened case. The influence of the line-coupling rotational distribution, which differs significantly in the two models, is discussed. The possible role of the finite duration of collision in rotational energy transfer is examined.
Solar occultation spectra obtained with a balloon-borne interferometer have been used to study continuous absorption by N2 and CO2 near 2400 cm-1 in the lower stratosphere. Synthetic continuum transmittances, calculated from published coefficients for far-wing absorption by CO2 lines and for pressure-induced absorption by the fundamental band of N2, are in fair agreement with the observed stratospheric values. The continuum close to the ν3 R-branch band head of CO2 is sensitive to the CO2 far-wing line shape. Therefore, given highly accurate knowledge of the N2 continuum from laboratory data, high-resolution stratospheric
spectra provide a sensitive means for in situ testing of various air-broadened CO2 line shapes at low temperatures.
Boissoles J., Menoux V., Le Doucen R., Boulet C., Robert D.,
Collisionally induced population transfer effects in infrared absorption spectra. II. The wing of the Ar-broadened ν3 band of CO2,
The Journal of Chemical Physics, 1989, Volume 91, Issue 4, Pages 2163-2171,
DOI: 10.1063/1.457024, https://doi.org/10.1063/1.457024.
Annotation
The absorption beyond the ν3‐band head of CO2 broadened by argon has been measured at room temperature. The absorption exhibits a strong sub‐Lorentzian behavior (several orders of magnitude) resulting from collisionally induced line interferences which transfer intensity from this wing region to the ν3‐band center. This wing absorption region implies detuning frequencies from resonances much larger than the reciprocal duration of collision. Consequently, finite duration of collisions in rotational energy transfers and initial correlations must be included in absorption calculation. A line‐by‐line coupling theory accounting for both these effects has been recently proposed [J. Chem. Phys. 89, 625 (1988)] and is applied here to a detailed study of the CO2–Ar collisional system. A convenient generalized detailed balance correction is introduced in this theory to overcome the limitation of the assumed resonant character of the energy transfer in the short time limit with respect to the thermal time ( βℏ)−1. The calculated absorption is in quantitative agreement with experiment. The origin and the nature of the empirical correcting factor currently used in similar studies are clearly established on a firm physical basis.
The absorption by pure CO2 beyond the ν3 bandhead has been measured with a grating spectrometer. Experiments have been made in the 0–60-bar and 291–751-K pressure and temperature ranges. Our room temperature determinations are in good agreement with previous ones and the measured temperature dependence above room temperature is consistent with recent determinations below 300 K. Lorentzian calculations, modified by the introduction of a line shape corrective factor x, are presented. Good agreement between the observed and calculated spectra is obtained when a temperature independent x factor, determined by Cousin et al. at 296 K, is used.
M.Y. Perrin and J.M. Hartmann,
Temperature-dependent measurements and modeling of absorption by CO2–N2 mixtures in the far line-wings of the 4.3 μ m CO2 band,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1989, Volume 42, Issue 4, Pages 311-317,
DOI: 10.1016/0022-4073(89)90077-0.
Annotation
We present experimental results on the absorption by CO2-N2 mixtures in the 4.3 μm region. Measurements have been made in the 300–800 K and 0–60 bar ranges; these are in good agreement with previous determinations below 296 K. Frequency- and temperature-dependent factors χ are introduced in order to account for the subLorentzian behavior of the CO2 far line-wings. Their dependences on temperature are deduced from experimental results beyond the 4.3μm band-head in the 193–773 K range for both CO2-CO2 and CO2-N2 and fitted by simple analytical functions. Comparisons are presented between experimental and theoretical spectra on both the low- and high-frequency sides of the band (2100–2600 cm-1 range). It is shown that calculations using χ factors are inaccurate near line-centers at elevated pressures.
L. Mannik, J. C. Stryland,
The ν1 Band of Carbon Dioxide in Pressure-Induced Absorption. II. Density and Temperature Dependence of the Intensity; Critical Phenomena,
Canadian Journal of Physics, 1972, Volume 50, Issue 12, Pages 1355-1362,
DOI: 10.1139/p72-186.
Annotation
The ν1 band of gaseous carbon dioxide has been studied in pressure-induced absorption at temperatures of ~ 190, ~ 300, and ~ 470 K, over a density range from 0.5 to 300 amagat, and with path lengths from 0.007 to 56 m. The observed temperature variation of the binary absorption coefficient can be satisfactorily accounted for only by adding a quadrupole–quadrupole interaction term to the usual Lennard–Jones model for the inter-molecular potential. The band profile is in agreement with the theory of quadrupole-induced absorption. There is some increase in the intensity of the band near the critical point due to the divergence of the correlation length. A very marked increase in the intensity is possibly prevented by the "cancellation effect".
George Birnbaum,
The shape of collision broadened lines from resonance to the far wings,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1979, Volume 21, Issue 6, Pages 597-607,
DOI: 10.1016/0022-4073(79)90099-2.
Annotation
A line shape for collision-broadened lines applicable from the resonance region to the far wings is developed. An empirical correlation function is used to represent the known short and long time behavior of the true correlation function and to interpolate the unknown intermediate time regime. The resulting spectral shape is a simple analytic function which reduces to essentially the Van Vleck-Weisskopf equation when |ω−ω0|τ21, but which smoothly assumes an exponential behavior in the far wings where |ω−ω0|τ21. The time parameter, τ2, is a measure of the duration of collision and is related to the mean squared torque produced in bimolecular collisions. The effect of overlapping lines, also variations in the model correlation function on the line shape are considered. The theory is applied to the absorption in the high-frequency far wing of the 4.3υ band in CO2.
The shapes of the extreme wings of self-broadened CO2(lines have been investigated)in three spectral regions near 7000, 3800, and 2400 cm-1. Absorption measurements have been made on the high-wavenumber sides of band heads where much of the absorption by samples at a few atm is due to the extreme wings of strong lines whose centers occur below the band heads. New information has been obtained about the shapes of self-broadened CO2 lines as well as CO2 lines broadened by N2, O2, Ar, He, and H2. Beyond a few cm-1 from the line centers, all of the lines absorb less than Lorentz-shaped lines having the same half-widths. The deviation from the Lorentz shape decreases with increasing wavenumber, from one of the three spectral regions to the next. The absorption by the wings of H2- and He-broadened lines is particularly low, and the absorption decreases with increasing temperature at a rate faster than predicted by existing theories.
Буланин М.О., Булычев В.П., Гранский П.В., Коузов А.П., Тонков М.В.,
Исследование функций пропускания СО2 в области полос 4.3 и 15 мкм,
Проблемы физики атмосферы. Вып. 13, Ленинград, Изд. ЛГУ,
Ленинград, Издательство Ленинградского Государственного Университета, 1976, Pages 14-24.
Творогов С.Д., Несмелова Л.И.,
Радиационные процессы в крыльях полос атмосферных газов.,
Известия РАН. Серия Физика атмосферы и океана, 1976, Т. 12, № 6, Страницы 627 – 633.
Fomin V.V., Tvorogov S.D.,
Formation of far wings contour of spectral lines broadened by a foreign gas; analysis of exponential decrease of continuous absorption beyond the band head of the 4.3 µm band of CO2,
Applied Optics, 1973, Volume 12, Issue 3, Pages 584-589,
DOI: 10.1364/AO.12.000584, https://doi.org/10.1364/AO.12.000584.
Annotation
This paper presents a problem on the contour of a spectral line far off from its center. Integral representation of the absorption coefficient obtained in the paper by Anderson [ Phys. Rev. 76, 647 ( 1949)] is used as a base. The problem is solved within adiabatic and binary collisions. Asymptotic methods are used for estimating the integrals over the collision parameters. Two formulas are obtained for the shape of line wings, one of which is of exponential form. On the basis of the theory developed, an interpretation is given for the radiation absorbed beyond the 4.3-μ band of CO2 due to the strong line wings near the band center.
Гальцев А.П., Осипов В.М., Шереметьева Т.А.,
Определение параметров контура линий СО2 методом минимизации,
Известия АН СССР. Серия Физика атмосферы и океана, 1973, Volume 9, no. 11, Pages 1195-1200.
Кузнецова Э.С., Осипов В.М., Подкладенко М.В.,
Исследование поглощения СО2 за кантом полосы 4.3 мкм при повышенных температурах,
Оптика и спектроскопия, 1975, Т. 38, Выпуск 11, Страницы 36-39.
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
Коэффициент поглощения света в крыле полосы 4,3 мкм СО2,
Известия вузов СССР, сер. Физика, 1980, Volume 10, Pages 106-107.
Несмелова Л.И., Творогов С.Д.,
Зависимость классического потенциала межмолекулярного взаимодействия от температуры и коэффициент поглощения света в крыле полосы 4.3 мкм СО2,
Спектральные проявления межмолекулярных взаимодействий в газах,
Новосибирск:, Наука, Сибирское отделение, 1982, Страницы 127-142.
B.H. Winters, S. Silverman, W.S. Benedict,
Line shape in the wing beyond the band head of the 4·3 μ band of CO2,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1964, Volume 4, Issue 4, Pages 527-537,
DOI: 10.1016/0022-4073(64)90014-7.
Annotation
Quantitative absorpance measurements have been made in pure CO2 and mixtures of CO2 with N2 and O2 in a 10 m White Perkin-Elmer cell. With absorbing paths up to 50 m-atm, results have been obtained from the band head at 2397 cm-1 to 2575 cm-1. The continuous absorption, which is due to the extreme tails of the strong lines in the v3 band centered at 2349 cm-1, is much less than calculated with the Lorentz line shape. A good fit with the data is obtained with an empirical line-shape which retains the Lorentz pressure dependence but requires a nearly exponential modification of the frequency dependence.
Телегин Г.В., Фомин В.В.,
Расчет коэффициента поглощения в крыльях полос СО2,
5 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 3.,
Томск: ИОА СО АН СССР, Издательство ИОА, 1979, Pages 152-156.
Annotation
Telegin G.V., Fomin V.V.,
Calculation of the absorption coefficient in the wings of CO2 bands,
Proceedings of 5 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere. Part 3., Tomsk: IOA SO AN SSSR, IOA Publishing House, 1979, Pages 152-156.
Theabsorption coefficients of the v3, 4.3-µ CO2 band were measuredover a temperature range of about 1200° to 2400°K atvarious pathlengths. The hot CO2 sample was investigated in theexhaust jet of a small supersonic burner, while the jetcomposition was obtained using a radiation temperature measurement and asimple thermochemical calculation. The present experimental results are compared withexisting experimental values and theoretical calculations. The results indicate thatabove 2000°K a weak line approximation can be used todescribe the absorption or emission of the band. The apparentintegrated band intensity of the CO2 fundamental as a functionof temperature is also reported and discussed in relation toother measurements.
Москаленко Н.И., Ильин Ю.А.,
Экспериментальные исследования поглощения излучения атмосферными газами при повышенных температурах,
Труды 1 совещания по атмосферной оптике, 1976, Тезисы докладов, часть 1,
Томск, Издательство ИОА, 1976, Страницы 8-12.
Аннотация
Moskalenko N.I., Ilyin Yu.A. Experimental studies of absorption of radiation by atmospheric gases at high temperatures, Proceedings of the 1-st Meeting on Atmospheric Optics, Tomsk, 1976, Abstracts, part 1, pp. 8-12.
Гальцев А.П., Цуканов В.В.,
Расчет формы колебательно-вращательных поплос поглощения углекислого газа методом статистического моделирования,
Оптика и спектроскопия, 1979, Volume 46, Issue 3, Pages 467-473.
Annotation
Galtsev A.P., Tsukanov V.V., Calculation of the shape of vibrational-rotational bands of absorption of carbon dioxide by the method of statistical modeling, Optics and Spectroscopy, 1979, Volume 46, Issue 3, Pages 467-473.
Докучаев А.Б., Телегин Г.В., Тонков М.В., Фомин В.В., Фирсов К.М.,
Исследование пропускания в микроокнах прозрачности полосы 4.3 мкм СО2,
5 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 3. Томск: ИОА СО АН СССР,
Томск, Издательство ИОА, 1979, Pages 157-161.
Annotation
Dokuchaev A.B., Telegin G.V., Tonkov M.V., Fomin V.V., Firsov K.M., Investigation of the transmission in transparency micro-windows of the 4.3 μm CO2 band, 5 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere. Part 3. Tomsk: IAO SB AS USSR, Tomsk, IAO Publishing House, 1979, Pages 157-161.
Телегин Г.В., Фомин В.В.,
Аппроксимация температурных зависимостей коэффициенга поглощения в спектре углекислого газа,
Тезисы VI Всесоюзного симпозиума по молекулярной спектроскопии высокого и сверхвысокого разрешения, Ч.2, Томск: ИОА СО АН СССР,
Томск, Издательство ИОА, 1982, Страницы 105-107.
Аннотация
Telegin G.V., Fomin V.V., Approximation of the temperature dependences of the absorption coefficient in the spectrum of carbon dioxide, Abstracts of the VI All-Union Symposium on Molecular Spectroscopy of High and Ultrahigh Resolution, Part 2, Tomsk: IAO SB AS USSR, Tomsk, IOA Publishing House, 1982, Pages 105-107.
V. Robert Stull, Philip J. Wyatt, and Gilbert N. Plass,
The Infrared Transmittance of Carbon Dioxide,
Applied Optics, 1964, Volume 3, Issue 2, Pages 243–254,
DOI: 10.1364/AO.3.000243.
Annotation
The infrared transmittance of carbon dioxide has been calculated over a wide range of path lengths, pressures, and temperatures from 500 to 10,000 cm-1. Values of the transmittance are given at intervals of 2.5 cm-1. In addition, transmittance values are also given which have been averaged over larger intervals. All contributing spectral lines whose relative intensity is greater than 10-8 that of the strongest line in any particular band have been included in the calculation. In addition, the contributions from the eight major isotopic species have been included. The calculation of the vibrational energy levels included terms through the third power of the vibrational quantum number and also the effects of Fermi resonanse. The final transmittance tables were generated using the the quasi-random model of molecular band absorption.
Bernstein L. S. , Robertson D. C., Conant J. A. , Sandford B. P.,
Measured and predicted atmospheric transmission in the 4.0-5.3-µm region, and the contribution of continuum absorption CO2 and N2,
Applied Optics, 1979, Volume 18, Issue 14, Pages 2454-2461,
DOI: 10.1364/AO.18.002454.
Annotation
High resolution measurements of atmospheric transmission of sunlight from space to altitudes of 12.2 km, 8.53 km, and 5.48 km made over Johnston Island are reported. The spectral region covered is 4.0–5.3 µm. Comparisons of the measured transmission with theoretically synthesized transmission curves are presented. It is shown that the sharp spectral features due to molecular line-by-line absorption can be predicted accurately while the modeling of the continuum absorption features needs further development. A discussion of the current models for CO2 and N2 continuum absorption is presented. An alternative mechanism is proposed for continuum absorption, which is based on the spectral properties of atmospheric van der Waals molecular complexes such as CO2.N2 and N2.N2 dimers.
Докучаев А.Б., Тонков М.В.,
Определение формы крыльев колебательно-вращательных линий полосы двуокиси углерода,
Оптика и спектроскопия, 1980, Volume 48, Issue 4, Pages 738-744.
Annotation
Dokuchaev A.B., Tonkov M.V., Determination of the shape of the wings of the vibrational-rotational lines of the carbon dioxide band, Optics and Spectroscopy, 1980, Volume 48, Issue 4, Pages 738-744. (Russian version)
Sattarov, K., Tonkov, M.V.,
Infrared absorption in the wing of the ν3 vibrational-rotational band of CO2,
Optics and Spectroscopy, 1983, Volume 54, Pages 562.
Телегин Г.В., Фирсов К.М., Фомин В.В.,
Расчет коэффициента поглощения в спектре СО2. Микроокна полосы 4.3 мкм СО2,
Оптика и спектроскопия, 1980, Volume 49, Issue 6, Pages 1159-1163.
Annotation
Telegin G.V., Firsov K.M., Fomin V.V.,
Calculation of the absorption coefficient in the CO2 spectrum. Micro window strips 4.3 μm CO2,
Optics and Spectroscopy, 1980, Volume 49, Issue 6, Pages 1159-1163. (in Russian)
Москаленко Н.И., Паржин С.Н.,
Исследования спектров поглощения углекислого газа при повышенных давлениях,
6 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере, Томск:, 1981,
Томск, Издательство ИОА, 1981, Страницы 110-113.
Аннотация
Moskalenko N.I., Parzhin S.N.,
Studies of absorption spectra of carbon dioxide at elevated pressures,
6 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere, Tomsk:, 1981, Tomsk, IAO Publishing House, 1981, Pages 110-113.
Телегин Г.В., Фомин В.В.,
Расчет коэффициента поглощения в спектре СО2. Микроокна прозрачности и периферия полосы 4.3 мкм, уширение аргоном и гелием,
Оптика и спектроскопия, 1982, Т. 52, Выпуск 2, Страницы 247-252.
Аннотация
Telegin G.V., Fomin V.V.,
Calculation of the absorption coefficient in the CO2 spectrum. Transparency micro-windows and band periphery 4.3 μm, broadening by argon and helium,
Optics and Spectroscopy, 1982, Vol. 52, Issue 2, Pages. 247-252.
Bulanin, M. O., Dokuchaev, A. B., Tonkov, M. V., & Filippov, N. N.,
Influence of line interference on the vibration-rotation band shapes,
Journal of Quantitative Spectroscopy and Radiative Transfer, 1984, Volume 31, Issue 6, Pages 521-543,
DOI: 10.1016/0022-4073(84)90059-1.
Annotation
The shapes of the CO, v3, CO2, and v3 N2O fundamental vibration-rotation bands have been studied at various temperatures and in the presence of several perturbing gases. Also the half-widths of CO vibration-rotation lines have been measured at 78 K. In the region of line wings, the measured absorption coefficients deviate from those given by the superposition of Lorentzian profiles. These deviations are explained by the collision-induced line interference that causes redistribution of absorption inside the band. A theory of line mixing is formulated which is based on Markov approximation and on the strong collision model. Simple analytical expressions are obtained for the band shape. The computed shapes are in satisfactory agreement with the experimental results. The deviations from the Lorentz absorption observed in pure CO and in CO-N2 at low temperature are partially ascribed to the formation of van der Waals dimers.
Телегин Г.В., Фомин В.В.,
Аппроксимация температурных зависимостей коэффициенга поглощения в спектре СО2,
Оптика и спектроскопия, 1984, Выпуск 5, Страницы 821-827.
Аннотация
G.V. Telegin, V.V. Fomin
Approximation of the temperature dependences of the absorption coefficient in the CO2 spectrum
Optics and Spectroscopy, 1984, Vol.56, Issue 5, pp.821-827. (in Russian)
Адикс Т. Г., Гальцев А. П.,
Температурная зависимость коэффициента поглощения в канте полосы 4,3 мкм СО2,
Известия РАН. Серия Физика атмосферы и океана, 1984, Т. 20, № 7, Страницы 653-657.
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
О природе температурной зависимости коэффициента поглощения в далеком крыле полосы 4.3 мкм СО2,
Известия вузов СССР, сер. Физика, 1987, № 12, Страницы 42-45.
Kaplan L.D., Chahine M.T., Susskind J., Searl J.E.,
Spectral band passes for a high precision satellite sounder,
Applied Optics, 1977, Volume 16, no. 2, Pages 322-325,
DOI: 10.1364/AO.16.000322, https://doi.org/10.1364/AO.16.000322.
Annotation
Atmospheric temperature soundings with significantly improved vertical resolution can be obtained from carefully chosen narrow band-pass measurements in the 4.3-μm band of CO2 by taking advantage of the variation of the absorption coefficients, and thereby the weighting functions, with pressure and temperature. A set of channels has been found in the 4.2-μm region that is capable of yielding about 2-km vertical resolution in the troposphere. The concept of a complete system is presented for obtaining high resolution retrievals of temperature and water vapor distribution, as well as surface and cloud top temperatures, even in the presence of broken clouds.
Nesmelova L.I., O.B. Rodimova, S.D. Tvorogov,
Temperature dependence of the CO2 absorption coefficient in the wing of the 4.3 μm band.
Dep. VINITI, 1985, No. 7998-B85, 19s
J. M. Hartmann, L. Rosenmann, J. Taine,
Temperature and pressure dependences of absorption in the narrow R66 -R68 window of the 12C16O2 v3-band,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1988, Volume 40, Issue 2, Pages 93-99,
DOI: 10.1016/0022-4073(88)90147-1.
Annotation
Diode-laser measurements of absorption by CO2-N2 mixtures in the trough between the R66 and R68 lines of the 12C16O2v3-band are presented. Experiments have been performed in the 1.0–7.0 atm pressure range at temperatures of 296 and 370 K. The measured absorption is very different from that predicted by the addition of Lorentzian contributions. Theoretical calculations accounting for line-overlapping based on a fitting law are presented. Although the effects of line-overlapping are slightly underestimated, the agreement between experiments and calculations is quite good, for both the pressure and temperature dependences.
Кузнецов М.Н.,
Расчет поглощения крыльями линий СО2 в полосе 4.3 мкм,
Известия РАН. Серия Физика атмосферы и океана, 1988, Т. 24, № 4, Страницы 394-402.
J. Boissoles, J. M. Hartmann, M. Y. Perrin, D. Robert,
Collision-induced population transfer in infrared absorption spectra. III. Temperature dependence of absorption in the Ar-broadened wing of CO2 v3 band,
Journal of Chemical Physics, 1990, Volume 93, Issue 4, Pages 2217-2221,
DOI: 10.1063/1.459054, https://doi.org/10.1063/1.459054.
Annotation
Wepresent experimental and theoretical results on the absorption in theAr-broadened wing of the infrared CO2 v3 band. Measurements havebeen made in the 293–765 K temperature range for totalgas pressures up to 60 bar and are in goodagreement with previous determinations at room temperature. Calculations have beencarried out by using a line by line coupling theorypresented and tested previously [J. Chem. Phys. 89, 625 (1988)and 91, 2163 (1989)]. The theoretical approach accounts for bothline mixing and the wave-number dependence of the relaxation operator.It enables correct modeling of the temperature dependence of absorption.The strong sublorentzian absorption resulting from competitions between negative andpositive individual line contributions is analyzed.
J. Boissoles, C. Boulet, L. Bonamy and D. Robert,
Calculation of absorption in the microwindows of the 4.3 μm CO2 band from an ECS scaling analysis,
Journal of Quantitative Spectroscopy and Radiative Transfer, 1989, Volume 42, Issue 6, Pages 509-520,
DOI: 10.1016/0022-4073(89)90041-1.
Annotation
Fine coupling induced by collisions leads to drastic modifications of the absorption profile in the microwindows of the self- and N2-broadened v3 CO2 fundamental vibration-rotation band. Calculations of these modifications have been performed by using the energy-corrected sudden (ECS) scaling law. Linewidths have been inverted to obtain effective rotation-translation basis rate constants and to deduce R-R, P-P and R-P line couplings. The characteristics of these couplings are presented and discussed. Calculated ECS profiles in the microwindows are compared with experimental data and also with previous results based on a statistical fitting law. The ECS approach is particularly suitable for practical infrared spectroscopic applications including line-coupling effects.
Докучаев А.Б., Павлов А.Ю., Строгонова Е.Н., Тонков М.В.,
Влияние плотности газа на форму Q-ветвей полос ИК поглощения CO2 в области 5 мкм,
Optics and Spectroscopy, 1986, Volume 60, Pages 947.
Annotation
Dokuchaev, A. B., Pavlov, A.Y., Stroganova, E.N., Tonkov, M.V.
Effect of gas density on the shape of Q-branches of the IR absorption bands of CO2 in the 5 μm region
Opt. Spectrosc. 60 (1986) 585. (English Transl.)
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
Расчет атмосферного поглощения в области 2400 см-1,
7 Всесоюзн. симпозиум по молекулярной спектроскопии высокого и сверхвысокого разрешения, тезисы докладов, Томск,
Томск, Издательство ИОА, 1986, Страницы 148-152.
Аннотация
Nesmelova L.I., O.B. Rodimova, S.D. Tvorogov,
Calculation of atmospheric absorption in the region of 2400 cm-1,
7 All-Union. symposium on molecular spectroscopy of high and ultrahigh resolution, abstracts, Tomsk, 1986, pp. 148-152.
Докучаев А.Б., Тонков М.В.,
Связь формы полосы ν3 СO2 на ее периферии с процессами вращательной релаксации,
VII Всесоюзный симпозиум по молекулярной спектроскопии высокого и сверхвысокого разрешения, Томск: ИОА, Часть III, 1986,
Томск, Издательство ИОА, 1986, Pages 242-246.
Annotation
Dokuchaev A.B., Tonkov M.V.
Communication of the shape of the ν3 band of the CO2 on its periphery with the processes of rotational relaxation
in the book: VII All-Union Symposium on Molecular Spectroscopy of High and Ultra-High Resolution, Tomsk: IO, part III, 1986, p.242-246.
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
Температурная зависимость коэффициента поглощения СО2 в крыле полосы 4.3 мкм,
7 Всесоюзн. симпозиум по молекулярной спектроскопии высокого и сверхвысокого разрешения, тезисы докладов, Томск, 1986,
Томск, Издательство ИОА, 1986, Pages 143-147.
Annotation
Nesmelova L.I., O.B. Rodimova, S.D. Tvorogov,
Temperature dependence of the CO2 absorption coefficient in the wing of the 4.3 μm band,
7 All-Union. symposium on molecular spectroscopy of high and ultrahigh resolution, abstracts, Tomsk, 1986, pp. 143-147.
J.-.M. Hartmann,
Measurements and calculations of CO2 room-temperature high-pressure spectra in the 4.3 μm region,
Journal of Chemical Physics, 1989, Volume 90, Issue 6, Pages 2944–2950,
DOI: 10.1063/1.455894.
Annotation
Measurementsof the absorption by pure CO2 in the 4.3 µmregion are presented. They refer to the temperature of 291K and densities in the 1–80 amagat range. Calculations basedon the addition of Lorentzian contributions strongly overestimate the absorptionsince they do not account for line overlapping. The energycorrected sudden approximation (ECSA) is used to model line mixingwithin the impact approximation. The scaling parameters of this modelare deduced from line-broadening data. This calculation strongly underestimates theabsorption in the spectral region near the edges of thevibrational band, whereas it overestimates the absorption in the farwings of the lines. This is attributed to the impactapproximation which does not account for the frequency dependence ofthe relaxation operator. This dependence is roughly determined from ourresults; it is in good qualitative agreement with the fewcorresponding available results
Тонков М.В., Филиппов Н.Н.,
Расчет ab initio поглощения в области крыльев колебательно-вращательных полос в ИК спектрах газов,
VII Всесоюзный симпозиум по молекулярной спектроскопии высокого и сверхвысокого разрешения, Томск: ИОА, Часть II, 1986,
Томск, Издательство ИОА, 1986, Pages 133-137.
Annotation
Tonkov M.V., Filippov N.N.
Ab initio calculation of absorption in the region of the wings of vibrational-rotational bands in the IR spectra of gases.
in the book: VII All-Union Symposium on Molecular Spectroscopy of High and Ultrahigh Resolution, Tomsk: IAO, Part II, 1986, pp. 133-137.
Cаттаров Х.,
Исследование инфракрасных спектров углекислого газа и фреонов в условиях, близких к атмосферным,
Ленинград, Автореферат канд ф.-м. н., 1983, 18 С..
Аннотация
Sattarov H.
Study of infrared spectra of carbon dioxide and freons in conditions close to atmospheric
Thesis. Leningrad. 1983.18 p.
Jean-Michel Hartmann, Christian Boulet,
Line mixing and finite duration of collision effects in pure CO2 infrared spectra: Fitting and scaling analysis,
Journal of Chemical Physics, 1991, Volume 94, Pages 6406,
DOI: 10.1063/1.460270.
Annotation
Line broadening coefficients of the CO2–Ar fundamental 3 band are obtained experimentally and theoretically for temperatures from 120 to 765 K. The experimental results are obtained by Fourier-transform infrared spectroscopy. Theoretical values are provided ia quantum-mechanical (close coupling and coupled states) approaches as well as semiclassical (improved Smith–Giraud–Cooper and Robert–Bonamy) methods. The most up-to-date CO2–Ar ab initio intermolecular potential (J. M. Hutson, A. Ernesti, M. M. Law, C. F. Roche and R. J. Wheatley, J. Chem. Phys., 1996, 105, 9130) is employed for all calculations. For all the temperatures probed, theoretical values are found to be in a rather good agreement with experiment. In addition, the Raman Q(j) line broadening coefficients and the application of the random phase approximation are presented.
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
Спектральное поведение коэффициента поглощения в полосе 4.3 мкм СО2 в широком диапазоне температур и давлений,
Оптика атмосферы и океана, 1992, Volume 5, no. 9, Pages 939-946.
Annotation
Экспериментальные результаты ряда авторов по коэффициенту поглощения углекислого газа при самоуширении и уширении азотом в микроокнах и за кантом полосы 4,3 мкм СО2 в интервале температур 193—771 К и при давлениях от нормального до 60 Амага рассматриваются с точки зрения теории крыльев линий. Показывается, что вся эта совокупность данных может быть описана с высокой степенью точности в рамках этой теории с учетом зависимости потенциала межмолекулярного взаимодействия от температуры. Обсуждаются достоинства и недостатки других теоретических подходов к описанию крыльев спектральных линий.
Nesmelova L. I., Rodimova O. B., Tvorogov S. D. Spectral behavior of the absorption coefficients in the 4.3 μm CO2 band within a wide range of temperature and pressure. // Atmospheric and oceanic optics. 1992. V. 5. No. 09. P. 609-614.
L.I.Nesmelova, O.B.Rodimova, and S. D. Tvorogov,
Absorption coefficient in the infrared CO2 Q-branch,
SPIE . V.1811,
SPIE - The international society for optical engineering, 1992, Pages 295-297.
Annotation
The values of absorption coefficient K in the wings of the infrared CO2 Q-branches significantly differ from those isolated Lorentzian lines. It becomes now traditional to explain these deviations by line-mixing. Actually, presence of the small line separations in the Q-branches are greatly conductive to this point of view. It can be noted, however, that the largest deviations from the Lorentzian line calculations are observed in spectral regions comparatively far from the line centers. Therefore it would be interesting to know whether the line wing theory can be used to describe the observed frequency dependence of K or not.
Roney P.L., Reid F., Theriault J.M.,
TRANSMISSION WINDOW NEAR 2400 CM-1 - AN EXPERIMENTAL AND MODELING STUDY,
Applied Optics, 1991, Volume 30, Issue 15, Pages 1995-2004,
DOI: 10.1364/ao.30.001995.
Annotation
The absorption in the 2400-cm−1 region is dominated by continuum absorptions from carbon dioxide and nitrogen, and it is important to be able to describe the temperature dependence of these two continua. A series of measurements of atmospheric transmission over a 5.7-km range were carried out during the summer and winter seasons of 1988. Following a brief description of the experiments a selected number of spectra, covering the temperature range from −21.4 to 30.3°C, are presented. These measurements are compared with predictions by the atmospheric transmission model fascod2 and modified versions using models of the carbon dioxide and the nitrogen continua derived from experimental laboratory measurements. Finally, an improved temperature-dependent model for the nitrogen continuum is derived from atmospheric transmission measurements. The model covers the range of temperatures found in the troposphere and differs significantly from laboratory-based measurements.
Ma Q. , Tipping R.H.,
An improved quasistatic line shape theory: The effects of molecular motion on the line wing.,
Journal of Chemical Physics, 1994, Volume 100, no. 8, Pages 5567 - 5579,
DOI: 10.1063/1.467124.
Annotation
A theory is presented for the modification of the line-shape functions and absorption coefficient due to the breakdown of the quasistatic approximation. This breakdown arises from the effects of molecular motion and increases the absorption in the near wings. Numerical calculations for the high-frequency wing of the ν3 band of CO2 broadened by Ar are reported and it is shown that these effects are significant near the bandhead. The importance of such. corrections in other spectral regions and for other systems is discussed briefly.
Ma, Q., Tipping R.H.,
Extension of the quasistatic far-wing line shape theory to multicomponent anisotropic potentials,
Journal of Chemical Physics, 1994, Volume 100, no. 12, Pages 8720-8736,
DOI: 10.1063/1.466727.
Annotation
The formalism developed previously for the calculation of the far-wing line shape function and the corresponding absorption coefficient using a single-component anisotropic interaction term and the binary collision and quasistatic approximations is generalized to multicomponent anisotropic potential functions. Explicit expressions are presented for several common cases, including the long-range dipole-dipole plus dipole-quadrupole interaction and a linear molecule interacting with a perturber atom. After determining the multicomponent functional representation for the interaction between CO2 and Ar from previous published data, we calculate the theoretical line shape function and the corresponding absorption due to the v3 band of CO2 in the frequency region 2400-2580 cm-1 and compare our results with previous calculations carried out using a single-component anisotropic interaction, and with the results obtained assuming Lorentzian line shapes. The principal uncertainties in the present results, possible refinements of the theoretical formalism, and the applicability to other systems are discussed briefly.
J. M. Hartmann and F. L’Haridon,
Simple modeling of line‐mixing effects in IR bands. I. Linear molecules: Application to CO2,
Journal of Geophysical Research: Planets, 1995, Volume 103, Pages 6467,
DOI: 10.1063/1.470424, https://doi.org/10.1063/1.470424.
Annotation
A simple approach is developed in order to model the influence of collisions on the shape of infrared absorption by linear molecules. It accounts for line‐mixing effects within, as well as between, the different branches (P, Q, R) of the band. It is based on use of the strong collision model, of a classical representation of rotational levels, and of the rigid rotor approximation. The absorption coefficient then has a very simple analytical expression; its wave number and pressure dependencies are computed by using eight parameters which depend on the considered vibrational transition, the temperature, and the nature of the perturber only. These quantities are band‐averaged values of the detailed spectroscopic and collisional parameters of the molecular system. Tests of the model are presented in the ν3 and 3ν3 bands of CO2 perturbed by He and Ar at elevated pressures. They demonstrate the accuracy of our approach in accounting for the effects of collisions on the spectral shape in a wide density range; indeed, the superposition of Lorentzian individual lines at low pressure, as well as the collapse (narrowing) of the band at very high pressure are satisfactory predicted.
Tvorogov S.D.,
Problem of spectral line periphery in atmospheric optics,
Atmospheric and Oceanic Optics, 1995, Volume 8, no. 01-02, Pages 7-13.
Annotation
Творогов С.Д. Проблема периферии контура спектральных линий в атмосферной оптике, Оптика Атмосферы и Океана, 8, №1-2, 18-30 (1995)
Подведены некоторые итоги решения задачи о периферии контура спектральных линий. Возможности построенной теории крыльев линий для существенных спектроскопических приложений в атмосферной оптике проиллюстрированы несколькими примерами.
Some of the results obtained from solving the problem of spectral line periphery are summarized. Several examples are given to illustrate the potentialities of our line wing theory as applied to important spectroscopic uses in atmospheric optics.
L. Ozanne, Q. Ma, Nguyen-Van-Thanh, C. Brodbeck, J. P. Bouanich, J. M. Hartmann, C. Boulet, R. H. Tipping,
Line-mixing, finite duration of collision, vibrational shift, and non-linear density effects in the v3 and 3v3 bands of CO2 perturbed by Ar up to 1000 bar,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1997, Volume 58, Issue 2, Pages 261-277,
DOI: 10.1016/S0022-4073(97)00007-1.
Annotation
We present high-density experimental and theoretical results on CO2---Ar gas-phase absorption in the ν3 and 3ν3 infrared bands. Measurements have been made at room temperature for pressures up to 1000 bar in both the central and wing regions of the bands. A non-linear perturber density dependence of the absorption, clearly shown in the far wing, is attributed to the finite volume of the molecules. Furthermore, experiments show vibrational dephasing and narrowing effects. We have performed line-mixing computations based on the Energy Corrected Sudden approximation (ECS impact model). Significant discrepancies between experimental and calculated spectra appear when pressure increases. We then tested the influence of the finite duration of collision by using interpolations between ECS and quasi-static calculations, and we have evaluated the sensitivity of the band profiles to the interbranch mixing effects. Finally, an effective width is used in order to take other effects into account.
Ma Q., Tipping R.H.,
The distribution of density matrices over potential-energy surfaces : application to the calculation of the far-wing line shapes for CO2,
Journal of Chemical Physics, 1998, Volume 108, no. 9, Pages 3386 - 3399,
DOI: 10.1063/1.475774.
Annotation
Within the formalism developed previously for the calculation of the far-wing line shape for molecular systems, most of the computer resources were used to diagonalize anisotropic potential-energy matrices whose sizes are determined by the number of states included. As this number is increased, one expects the results to converge. However, for some systems of atmospheric interest, e.g., CO2, the convergence is so slow that one is unable to obtain converged results within reasonable computer limitations. In the present paper, a new formalism is presented in which the eigenfunctions of the orientations of the system, not the states themselves, are chosen as the complete set of basis functions in Hilbert space. In this case, the diagonalization procedure is unnecessary and one can include as many states as desired. The main computational task is transformed from a diagonalization procedure to the carrying out of multidimensional integrations over the continuous orientational variables. In practice, the integrals are approximated by
multidimensional summations over discrete values, the number of which is determined by the resolution required so that the approximated integrals are close to their true values. By choosing reasonable resolutions based on the smooth functional behavior of the integrands, one is able to evaluate the required integrations within reasonable computer time. Furthermore, by introducing weighting functions which are the distribution of the density matrices over potential-energy surfaces, one can reduce the multidimensional integrations to two-dimensional ones. The calculation of the weighting functions can also be carried out with reasonable CPU time and furthermore needs only to be done once for a given molecular system at a specified temperature. Using these as input data, the remaining calculations of the line shapes and corresponding absorption for given potential parameters become straightforward. The formalism is applied in the present paper for linear molecular systems and sample calculations for CO2 –CO2 and CO2 –N2 are presented. To our
knowledge, these are the first, first-principle calculations for the far-wing line shape of CO2 except for the much simpler CO2 –rare gas systems.
Theoretical results for the far-wing line shapes and corresponding absorption coefficients in the high-frequency wing of the ν3 fundamental band of self-broadened CO2 are presented for a number of temperatures between 218 and 751 K. These first-principles calculations are made assuming binary collisions within the framework of a quasi-static theory with a more accurate interaction potential than in previous calculations. The theoretical results are compared with existing laboratory data and are in good agreement for all the temperatures considered.
Ma Q., Tipping R.H., Boulet C.,
The frequency detuning and band-average approximations in a far-wing line shape theory satisfying detailed balance,
Journal of Chemical Physics, 1996, Volume 104, no. 24, Pages 9678 - 9688,
DOI: 10.1063/1.471730.
Annotation
We develop the basic formalism of a far-wing line shape theory that satisfies the detailed balance principle. For molecular systems of interest, e.g., CO2 –Ar at room temperature or higher, there are many individual vibration–rotational lines in a given band and many bands in the spectrum. In such cases, one must make additional approximations in order to carry out accurate calculations of the absorption coefficient using a reasonable amount of computer time. In the present paper, we discuss two such simplifications: the frequency detuning approximation of the line-coupling functions and the band-average approximation. We then apply the theory to a calculation of the far-wing absorption of the ν3 band of CO2 perturbed by Ar, successively including the effects of more lines in the calculations by increasing J max from 40 to 108. From the results of this work, we find that the frequency detuning approximation is good only for frequencies of interest far from the band center. In addition, we find that contrary to previous assertions of the adequacy of the first-order band-average approximation, the higher-order terms are significant. To a good approximation these can be incorporated by introducing a frequency shift in the first-order results so that extensive additional calculations are not required.
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
О поведении коэффициента поглощения при изменении давления в крыле полосы 4.3 мкм СО2,
Оптика атмосферы и океана, 1991, Volume 4, Issue 7, Pages 745-752.
Annotation
Коэффициент поглощения в крыле полосы 4,3 мкм СO2 при давлениях до 80 Амага рассчитан на основе теории крыльев линий. Данные расчета хорошо согласуются с измеренными значениями. Отмечены сходство и различие использованного в работе теоретического подхода и метода, основанного на расчете матричных элементов оператора релаксации.
Nesmelova L. I., Rodimova O. B., Tvorogov S. D. On the pressure dependence of the CO2 absorption coefficient in the wing of the 4.3 μm band. // Atmospheric and oceanic optics. 1991. V. 4. No. 07. P. 533-537. (translated from Russian)
L.I.Nesmelova, O.B.Rodimova, and S. D. Tvorogov,
On the role of continual and selective absorption in the wing of the 4. 3 μm CO2 band at high pressures and temperatures,
SPIE V.1811,
SPIE - The international society for optical engineering, 1992, Pages 291-294.
Annotation
The absorption coefficient at a given frequency can be roughly represented as a sum of two terms. One of them accounts for absorption at the nearest line and another represents some background due to absorption at a distant line.
R. Rodrigues, C. Boulet, L. Bonamy, J. M. Hartmann,
Temperature, pressure, and perturber dependencies of line-mixing effects in CO2 infrared spectra. II. Rotational angular momentum relaxation and spectral shift in Σ->Σ bands,
Journal of Chemical Physics, 1998, Volume 109, Pages 3037,
DOI: 10.1063/1.476921.
Annotation
TheEnergy Corrected Sudden approach is used in order to deducecollisional parameters and to model infrared quantities in Sigma->Sigma bandsof CO2-He and CO2-Ar mixtures at room temperature. Measurements arefirst used for the determination (from a fit) of therotational angular momentum relaxation time and of some parameters representativeof the imaginary part of the relaxation operator. It isshown that line-broadening data as well as absorption in boththe wing and central part of the v3 and 3v3bands lead to consistent determinations. The model is then usedfor detailed analysis of line-mixing effects. The influences of pressure,of the band spectral structure, and of the collision partnerare studied. Differences between the effects of collisions with Heand Ar are pointed out and explained.
The shape of the far wing of self- and N2-broadened CO2 lines has been investigated in the 2150–2250-cm−1 spectral region, i.e., on the low wavenumber side of the lines of the very intense v3 band of 12C16O2 in a temperature range of atmospheric interest (200–300 K). The experimental results have been compared to calculated values based on the AFGL 1986 compilation. It appears that a symmetrical sub-Lorentzian line shape based on experiments made on the high wavenumber side cannot reproduce experiments. Comparison with experiments made at room temperature shows that the asymmetry of the correcting line shape factor χ strongly increases when decreasing the temperature.
L. Ozanne, Nguyen-Van-Thanh, C. Brodbeck, J. P. Bouanich, J. M. Hartmann, and C. Boulet,
Line mixing and nonlinear density effects in the ν3 and 3ν3 infrared bands of CO2 perturbed by He up to 1000 bar,
Journal of Chemical Physics, 1995, Volume 102, Issue 19, Pages 7306,
DOI: 10.1063/1.469042.
Annotation
Wepresent high density experimental and theoretical results on CO2–He absorptionin the v3 and 3v3 infrared bands. Measurements have beenmade at room temperature for pressures up to 1000 barin both the central and wing regions of the bands.Computations are based on an impact line-mixing approach in whichthe relaxation operator is modeled with the energy corrected sudden(ECS) approximation. Comparisons between experimental and calculated results demonstrate theaccuracy of the ECS approach when applied to band wingsand band centers at moderate densities. On the other hand,small but significant discrepancies appear at very high pressures. Theyare attributed to a number of reasons which include nonlineardensity dependence due to the finite volume of the molecules,neglected contributions of vibration to the relaxation matrix, and incorrectmodeling of interbranch mixing.
Golovko V. F.,
Calculation of carbon dioxide absorption spectra in wide spectral regions,
Atmospheric and Oceanic Optics, 2001, Volume 14, Issue 9, Pages 807-812.
Annotation
A somewhat unexpected hypothesis of the Fermi distribution of photon fluctuations connected with a two-level system is chosen to explain the exponential shape of the absorption line profile in its far wing. A preference is given to studies of the properties of direct interaction between radiation and a matter being in chaotic thermal motion, rather than to the influence of intermolecular interaction on the line shape. A simple exponential form for the far wings of absorption lines is obtained. Examples of modeling absorption in wide spectral regions from 442 to 9648 cm-1 are given for both pure CO2 and CO2-Y mixtures, where Y is one of the buffer gases: N2, H2, He, Ar, or Xe.
S.A. Tashkun, V. I. Perevalov, J-L. Teffo, A. D. Bykov and N. N. Lavrentieva,
CDSD-1000, the high-temperature carbon dioxide spectroscopic databank,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2003, Volume 82, Issue 1, Pages 165-196,
DOI: 10.1016/S0022-4073(03)00152-3.
Annotation
We present a high-temperature version, CDSD-1000, of the carbon dioxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air-broadened half-widths) of the four most abundant isotopic species of the carbon dioxide molecule. The reference temperature is Tref=1000°K and the intensity cutoff is Icut=10−27 cm−1/moleculecm−2. More than 3 million lines covering the 260–8310, 418–2454, 394–4662, and 429–2846 cm−1 spectral ranges for 12C16O2, 13C16O2, 12C16O18O, and 12C16O17O, respectively, are included in CDSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonians and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulations of several low- and medium-resolution high-temperature (T=800-3000 K) spectra have been performed in order to validate the databank. Comparisons of CDSD-1000 with other high-temperature databanks HITEMP, HITELOR, and EM2C are also given. CDSD-1000 is able to reproduce observed spectra in a more satisfactory way than the high-resolution databank HITEMP for temperatures higher than 1000°K. The databank is useful for studying high-temperature radiative properties of CO2. CDSD-1000 is freely accessible via the Internet.
Domanskaya A. V., Filippov N. N., Grigorovich N. M., Tonkov M. V,
Modelling of the rotational relaxation matrix in line-mixing effect calculations,
Molecular Physics, 2004, Volume 102, Issue 16-17, Pages 1843-1850.
Annotation
In this work we discuss and compare the properties of empirical rotational relaxation matrices, which are responsible for the line-mixing effects in IR absorption in the gas phase. The energy-corrected sudden approximation, the strong collision model, the adjusted branch coupling (ABC) model, and the varied collision efficiency (VCE) model are considered. The ABC and VCE models are applied to the band shape calculations for CO2 and CF4 spectra in rare gas mixtures. The VCE model proved to be better for this purpose.
A. Predoi-Cross, A. D. May, A. Vitcu, J. R. Drummond, J.-M. Hartmann and C. Boulet,
Broadening and line mixing in the 2000 <-- 0110, 1110 <-- 00 00 and 12 20<--0110 Q branches of carbon dioxide: Experimental results and energy-corrected sudden modeling,
Journal of Chemical Physics, 2004, Volume 120, Pages 10520,
DOI: 10.1063/1.1738101.
Annotation
Usingboth a difference frequency spectrometer and a Fourier transform spectrometer,we have measured transitions in the 12 20 <-- 01 10 band of carbondioxide at room temperature and pressures up to 19 atm.The low-pressure spectra were analyzed using a variety of standardspectral profiles, all with an asymmetric component to account forweak line mixing. For this band, we have been ableto retrieve experimental line strengths and the broadening and weakmixing parameters. In this paper we also compare the suitabilityof the energy-corrected sudden model to predict mixing in thetwo previously measured Q branches 20 00<-- 01 10, the 11 10<--00 00, and thepresent Q branch of pure CO2, all at room temperature.
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
N. N. Filippov, V. P. Ogibalov and M. V. Tonkov,
Line mixing effect on the pure CO2 absorption in the 15 μm,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2002, Volume 72, Issue 4, Pages 315-325,
DOI: 10.1016/S0022-4073(01)00124-8.
Annotation
The IR absorption of the pure CO2 gas in the region of 15 μm was examined. A special attention was given to the line mixing effect that influences the spectral shape of the vibration–rotation absorption bands in the Q-branch regions. Two methods in shape description were analyzed. The first method uses the Rosenkranz line shapes with the line mixing parameters, which are found from an empirical rotational relaxation matrix. The second method is based on the strong collision model with adjusted branch coupling (ABC-model). The merits and the demerits of these two methods are discussed, and the results of the corresponding calculations are compared to the measured shapes. It is inferred that the ABC-model for the absorption coefficient calculations can be successfully applied for solving the non-LTE radiative transfer problem in CO2 bands in the atmospheres of Earth-like planets.
Collision-induced absorption is of great importance to the overall radiative budget in dense CO2-rich atmospheres, but its representation in climate models remains uncertain, mainly due to a lack of accurate experimental and theoretical data. Here we compare several parameterisations of the effect, including a new one that makes use of previously unused measurements in the 1200–1800 cm−1 spectral range. We find that a widely used parameterisation strongly overestimates absorption in pure CO2 atmospheres compared to later results, and propose a new approach that we believe is the most accurate possible given currently available data.
J.-M. Hartmann, C. Boulet, H. Tran, and M. T. Nguyen,
Molecular dynamics simulations for CO2 absorption spectra. I. Line broadening and the far wing of the v3 infrared band,
Journal of Chemical Physics, 2010, Volume 133, Issue 14, Article 144313,
DOI: 10.1063/1.3489349, http://link.aip.org/link/doi/10.1063/1.3489349.
Annotation
Classical molecular dynamics simulations (CMDS) have been carried out for gaseous CO2 starting from the intermolecular potential energy surface. Through calculations for a large number of molecules treated as rigid rotors, various autocorrelation functions (ACFs) are obtained together with probabilities of rotational changes. Those used in the present paper are the ACFs of the center of mass velocity and of the molecular orientation, and the conditional probability of a change of the angular speed. They enable calculations, respectively, of the mass diffusion coefficient, of the infrared (dipolar) band shape including the wings, and of individual line-broadening coefficients. It is shown that these calculations, free of any adjustable parameter, lead to good agreement with measured values. This is expected from previous studies for the mass diffusion coefficient and line-broadening coefficients, but it is, to our knowledge, the first demonstration of the interest of CMDS for the prediction of band wings. The present results thus open promising perspectives for the theoretical treatment of the difficult problem of far wings profiles.
Tomoaki Tanaka, Masashi Fukabori, Takafumi Sugita, Tatsuya Yokota, Ryoichi Kumazawa, Takeshi Watanabe, Hideaki Nakajima,
Line shape of the far-wing beyond the band head of the CO2 v3 band,
Journal of Molecular Spectroscopy, 2008, Volume 252, Issue 2, Pages 185-189,
DOI: 10.1016/j.jms.2008.08.004.
Annotation
Carbon dioxide is one of the most important trace gases in the terrestrial atmosphere. The spectral data required in remote sensing are the spectral parameter of each absorption line and a line shape model. This paper describes the absorption properties of CO2 near 2400 cm-1; these properties are of interest to those in the atmospheric temperature sounding field. The shape of the far-wing of N2- and O2-broadened CO2 lines was investigated in the 2200–2500 cm-1 spectral region in a temperature range of atmospheric interest (230–318°K). We focused on the higher rotational quantum number of the R-branch in the v3 band, where the effect of the far-wing is enhanced. The effect of the far-wing has been studied extensively by others, since the CO2 v3 band is known to exhibit sub-Lorentzian behavior. Here, we show the observed spectra along with calculated spectra for five temperatures. We used first-order line-mixing and the x-factor, which accounts for the effect of the far-wing, to create the calculated spectra. Our results provide new knowledge of quantum interference of the spectral line in the v3 band of CO2.
Bharadwaj S.P., Modest M.F.,
Medium resolution transmission measurements of CO2 at high temperature – an update,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2007, Volume 103, Pages 146-155,
DOI: 10.1016/j.jqsrt.2006.05.011, https://doi.org/10.1016/j.jqsrt.2006.05.011.
Annotation
The current work presents updated measurements of narrow-band transmission for the 2.0, 2.7 and 4.3 μm bands of CO2 at temperatures of up to 1550 K. In addition, measurements for 15 μm the band of CO2 are also presented for the first time. Data were collected with an improved drop tube design (as compared to the earlier measurements) and an FTIR-spectrometer. The measured data were compared with the CDSD and HITEMP databases, as well as with previous data obtained from the old drop tube apparatus. The new data have less uncertainties at extreme temperatures than the old data and eliminate some of the problems associated with subtraction of the emission signal with the old apparatus. The data show minor discrepancies with the high-resolution databases, particularly with HITEMP at higher temperatures, but in general agreement is good.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
Nikolai N. Filippov, Ruslan E. Asfin, Tatiana N. Sinyakova, Ivan M. Grigoriev, Tatiana M. Petrova, Alexandr M. Solodov, Alexandr A. Solodov and Jeanna V. Buldyreva,
Experimental and theoretical studies of CO2 spectra for planetary atmosphere modelling: region 600–9650 cm−1 and pressures up to 60 atm,
Physical Chemistry Chemical Physics, 2013, Volume 15, Pages 13826-13834,
DOI: 10.1039/C3CP50279A.
Annotation
Extensive experimental studies of room-temperature carbon dioxide absorption coefficients are reported for a wide range of wavenumbers and pressures requested in atmospheric spectra modelling. The quality of measurements is optimised by the use of two complementary setups with long- and short-path optical cells for low and high gas densities, respectively. The recorded spectra provide a representative picture of band-shape evolutions from gaseous to nearly liquid phases of CO2 and enable a theoretical analysis of line-mixing effects. Various kinds of vibrational bands (Σ←Σ, Π←Σ as well as Π←Π transitions) are modelled using a specific, non-Markovian in the general case, approach of Energy-Corrected Sudden type which is based on the symmetric relaxation matrix and, in contrast to the standard ECS model used for infrared absorption calculations, ensures automatically the fundamental relations of detailed balance and double-sided sum rules. Moreover, this method properly accounts for the vibrational angular momenta of the initial and final molecular states and allows including Coriolis resonances via the usual Herman-Wallis factors in the dipole transition moments. With a set of ECS parameters previously obtained for isotropic and anisotropic Raman spectra modelling, completely neglected imaginary part of the relaxation operator and a simple change in the tensorial rank to get the dipole absorption case in the working formulae, the computed spectra reproduce quite correctly the vibrotational band shapes up to 20 amagat without any additional parameter. An empirical correction factor tentatively introduced to account globally for the Coriolis effects on the relaxation matrix leads to better matches with high-density band shapes but its role merits further studies with an accurately modelled imaginary part of the relaxation matrix.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
T. E. Klimeshina, T. M. Petrova, O. B. Rodimova, A. A. Solodov, A. M. Solodov,
CO2 absorption in band wings in near IR,
Atmospheric and Oceanic Optics, 2015, Volume 28, Issue 5, Pages 387–393,
DOI: 10.1134/S1024856015050073, https://doi.org/10.1134/S1024856015050073.
Annotation
The CO2 absorption was measured in the 7000 and 8000 cm–1 regions. The absorption coefficients were calculated using the asymptotic line wing shape theory. Line shape parameters were found from fitting to experimental data. The calculation results agree well with the measurement data. According to the line wing theory, the absorption in the band wings is caused by the wings of strong lines of an adjacent band. Within these assumptions, experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7000 and 8000 cm–1 regions can provide information on the line shape at frequency detuning from several tens to several hundreds of half-widths. The results support the hypothesis that line shape parameters in the line wings related to transitions with the same initial state are close to each other. Deviations from a Lorentzian profile are found for some CO2 bands and turn out different for the wings of different bands
Yu.I. Baranov,
On the significant enhancement of the continuum-collision induced absorption in H2O+CO2 mixtures,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2016, Volume 175, Pages 100-106,
DOI: 10.1016/j.jqsrt.2016.02.017, https://doi.org/10.1016/j.jqsrt.2016.02.017.
Annotation
The IR spectra of water vapor–carbon dioxide mixtures as well as the spectra of pure gas samples have been recorded using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm−1 in order to explore the effect of colliding CO2 and H2O molecules on their continuum absorptions. The sample temperatures were 294°, 311°, 325° and 339°K. Measurements have been conducted at several different water vapor partial pressures depending on the cell temperature. Carbon dioxide pressures were kept close to the three values of 103, 207 and 311 kPa (1.02, 2.04 and 3.07 atm). The path length used in the study was 100 m. It was established that, in the region around 1100 cm−1, the continuum absorption coefficient CH2O+CO2 is about 20 times stronger than the water–nitrogen continuum absorption coefficient CH2O+N2. On the other hand, in the far wing region (2500 cm−1) of the ν3 CO2 fundamental band, the binary absorption coefficient CCO2+H2O appears to be about one order of magnitude stronger than the absorption coefficient in CCO2+CO2 pure carbon dioxide. The continuum interpretation and the main problem of molecular band shape formation are discussed in light of these experimental facts.
Jean-Michel Hartmann, Christian Boulet, Duc Dung Tran, Ha Tran, Yury Baranov,
Effect of humidity on the absorption continua of CO2 and N2 near 4 μm: Calculations, comparisons with measurements, and consequences for atmospheric spectra,
The Journal of Chemical Physics, 2018, Volume 148, Issue 5, Article 054304,
DOI: 10.1063/1.5019994.
Annotation
We present a theoretical study of the effects of collisions with water vapor molecules on the absorption, around 4 μm, in both the high frequency wing of the CO2 ν3 band and the collision-induced fundamental band of N2. Calculations are made for the very first time, showing that predictions based on classical molecular dynamics simulations enable, without adjustment of any parameter, very satisfactory agreement with the few available experimental determinations. This opens the route for a future study in which accurate temperature-dependent (semi-empirical) models will be built and checked through comparisons between computed and measured atmospheric spectra. This is of interest since, as demonstrated by simulations, neglecting the humidity of air can lead to significant modifications of the atmospheric transmission (and thus also emission) between 2000 and 2800 cm−1.
Daniel D. Lee, Fabio A. Bendana, Anil P. Nair, Daniel I. Pineda, R. Mitchell Spearrin,
Line mixing and broadening of carbon dioxide by argon in the v3 bandhead near 4.2 μm at high temperatures and high pressures,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2020, Volume 253, Article 107135,
DOI: 10.1016/j.jqsrt.2020.107135, https://doi.org/10.1016/j.jqsrt.2020.107135.
Annotation
Temperature-dependent line mixing and line broadening parameters were empirically-determined for rovibrational transitions (J = 99–145) in the (0000 → 0001) and (0110 → 0111) bandheads of carbon dioxide near 4.2 µm. Collisional effects by argon on the high rotational energy lines (E″ = 3920–8090 cm-1) in the R-branch were studied over a range of temperatures from 1200–3000 K in a shock tube. Measured absorption spectra comprising the target lines in an argon bath gas at near-atmospheric pressures were fit with Voigt profiles to determine line-broadening coefficients, with temperature dependence accounted by a power law. With line broadening established, line-mixing effects were examined at elevated pressures up to 58 atm and similar temperatures, reflecting conditions in high-pressure combustion environments. A modified exponential gap model for line mixing was developed to capture the pressure and temperature dependence of collisional transfer rates for the bandhead region using the relaxation matrix formalism.
N. I. Moskalenko, O. V. Zotov, Yu. A. Il’in, M. S. Khamidullina Russian Physics Journal · July , DOI: , Complex Investigation of the Absorption and Emission Spectra of Carbon Dioxide,
Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, 2017, Volume 59, no. 12, Pages 2017-2024,
DOI: 10.1007/s11182-017-1009-7.
Annotation
Absorption and emission spectra of carbon dioxide are measured and analyzed for temperatures 220–2500 K in the spectral range 1–25 μm. Intensities and half-widths of the spectral lines are determined and hightemperature atlas of the spectral lines’ parameters is compiled. Based on the developed mathematical model, the parameters of spectral transmission functions of СО2 are obtained at different temperatures in the vibration-rotation and pressure-induced bands of СО2. Practical application of the obtained radiative characteristics is considered for solving problems of radiative heat exchange in planetary atmospheres and high-temperature media and designing optoelectronic systems intended for aero carriers monitoring.
Baranov, G.T. Fraser, W.J. Lafferty, A.A.Vigasin
, Collision-induced Absorption in the CO2 Fermi Triad for Temperatures from 211K to 296K, Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere, Editor(s) CLAUDE CAMY-PEYRET and ANDREI A.VIGASIN,
Dordrecht, Kluwer Academic Publishers, 2003, Pages 149-158.
Annotation
Absorption spectra of pure CO2 have been recorded in the vicinity of the 2675 cm−1 Fermi triad for temperatures between 211 K and 296 K. The 2ν1, ν1 + 2ν2, 2ν2 collision-induced components have been extracted from the measured spectra, including for the low frequency band at 2547 cm−1, which is strongly masked by the ν3 wing absorption. Dimeric features are clearly seen on top of the structureless profiles. Integrated intensities of the Fermi-triad components are determined as a function of temperature.
J. Lamouroux, H. Tran, A.L. Laraia, R.R. Gamache, L.S. Rothman, I.E. Gordon, J.-M. Hartmann,
Updated database plus software for line-mixing in CO2 infrared spectra and their test using laboratory spectra in the 1.5–2.3 μm region,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2010, Volume 111, Issue 15, Pages 2321-2331,
DOI: 10.1016/j.jqsrt.2010.03.006.
Annotation
XVIth Symposium on High Resolution Molecular Spectroscopy (HighRus-2009)
In a previous series of papers, a model for the calculation of CO2-air absorption coefficients taking line-mixing into account and the corresponding database/software package were described and widely tested. In this study, we present an update of this package, based on the 2008 version of HITRAN, the latest currently available. The spectroscopic data for the seven most-abundant isotopologues are taken from HITRAN. When the HITRAN data are not complete up to J″=70, the data files are augmented with spectroscopic parameters from the CDSD-296 database and the high-temperature CDSD-1000 if necessary. Previously missing spectroscopic parameters, the air-induced pressure shifts and CO2 line broadening coefficients with H2O, have been added. The quality of this new database is demonstrated by comparisons of calculated absorptions and measurements using CO2 high-pressure laboratory spectra in the 1.5–2.3 μm region. The influence of the imperfections and inaccuracies of the spectroscopic parameters from the 2000 version of HITRAN is clearly shown as a big improvement of the residuals is observed by using the new database. The very good agreements between calculated and measured absorption coefficients confirm the necessity of the update presented here and further demonstrate the importance of line-mixing effects, especially for the high pressures investigated here. The application of the updated database/software package to atmospheric spectra should result in an increased accuracy in the retrieval of CO2 atmospheric amounts. This opens improved perspectives for the space-borne detection of carbon dioxide sources and sinks.
The shapes of the extreme wings of self-broadened CO2(lines have been investigated)in three spectral regions near 7000, 3800, and 2400 cm-1. Absorption measurements have been made on the high-wavenumber sides of band heads where much of the absorption by samples at a few atm is due to the extreme wings of strong lines whose centers occur below the band heads. New information has been obtained about the shapes of self-broadened CO2 lines as well as CO2 lines broadened by N2, O2, Ar, He, and H2. Beyond a few cm-1 from the line centers, all of the lines absorb less than Lorentz-shaped lines having the same half-widths. The deviation from the Lorentz shape decreases with increasing wavenumber, from one of the three spectral regions to the next. The absorption by the wings of H2- and He-broadened lines is particularly low, and the absorption decreases with increasing temperature at a rate faster than predicted by existing theories.
Гальцев А.П., Осипов В.М., Шереметьева Т.А.,
Определение параметров контура линий СО2 методом минимизации,
Известия АН СССР. Серия Физика атмосферы и океана, 1973, Volume 9, no. 11, Pages 1195-1200.
Москаленко Н.И., Ильин Ю.А., Паржин С.Н., Родионов Л.В.,
Индуцированное давлением поглощение ИК-излучения в атмосферах,
Известия АН СССР. Серия Физика атмосферы и океана, 1979, Т. 15, № 9, Страницы 912-919.
Аннотация
Moskalenko N.I., Ilyin Yu.A., Parzhin S.N., Rodionov L.V., Pressure-induced absorption of infrared radiation in atmospheres, Izvestia of the Academy of Sciences of the USSR. Series Physics of Atmosphere and Ocean, 1979, Vol. 15, No. 9, Pages 912-919.
Телегин Г.В., Фомин В.В.,
Расчет коэффициента поглощения в крыльях полос СО2,
5 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 3.,
Томск: ИОА СО АН СССР, Издательство ИОА, 1979, Pages 152-156.
Annotation
Telegin G.V., Fomin V.V.,
Calculation of the absorption coefficient in the wings of CO2 bands,
Proceedings of 5 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere. Part 3., Tomsk: IOA SO AN SSSR, IOA Publishing House, 1979, Pages 152-156.
Howard J. N., Burch D. E., Williams D.,
Infrared transmission of synthetic atmospheres. V. Absorption Laws for Overlapping Bands,
Journal of Optical Society of America, 1956, Volume 46, no. 6, Pages 452-455.
Annotation
Although Lambert's law Tν=e-kνw presumably applies to the absorption of gases in the infrared, the experimentally observed transmission T'ν cannot be expressed by a simple relation of this type. It is observed, however, that in regions where the atmospheric carbon dioxide and water vapor absorption bands overlap
T'ν(CO2+H2O) =T'ν(CO2) T'ν(H2O) provided the total pressure P is constant. It is found that the total absorption IAνdv for a synthetic atmospheric sample containing water vapor, carbon dioxide, and nitrogen can be expressed as IAνdv =IAν(H2O)dν+εIAν(CO2)dv, where IAν(H2O)dν and IAν(CO2)dv are given by the empirical relations obtained in earlier studies in the present series and ε is a fraction, which can be expressed in terms of the total absorption by water vapor.
Москаленко Н.И., Ильин Ю.А.,
Экспериментальные исследования поглощения излучения атмосферными газами при повышенных температурах,
Труды 1 совещания по атмосферной оптике, 1976, Тезисы докладов, часть 1,
Томск, Издательство ИОА, 1976, Страницы 8-12.
Аннотация
Moskalenko N.I., Ilyin Yu.A. Experimental studies of absorption of radiation by atmospheric gases at high temperatures, Proceedings of the 1-st Meeting on Atmospheric Optics, Tomsk, 1976, Abstracts, part 1, pp. 8-12.
V. Robert Stull, Philip J. Wyatt, and Gilbert N. Plass,
The Infrared Transmittance of Carbon Dioxide,
Applied Optics, 1964, Volume 3, Issue 2, Pages 243–254,
DOI: 10.1364/AO.3.000243.
Annotation
The infrared transmittance of carbon dioxide has been calculated over a wide range of path lengths, pressures, and temperatures from 500 to 10,000 cm-1. Values of the transmittance are given at intervals of 2.5 cm-1. In addition, transmittance values are also given which have been averaged over larger intervals. All contributing spectral lines whose relative intensity is greater than 10-8 that of the strongest line in any particular band have been included in the calculation. In addition, the contributions from the eight major isotopic species have been included. The calculation of the vibrational energy levels included terms through the third power of the vibrational quantum number and also the effects of Fermi resonanse. The final transmittance tables were generated using the the quasi-random model of molecular band absorption.
Москаленко Н.И., Паржин С.Н.,
Исследования спектров поглощения углекислого газа при повышенных давлениях,
6 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере, Томск:, 1981,
Томск, Издательство ИОА, 1981, Страницы 110-113.
Аннотация
Moskalenko N.I., Parzhin S.N.,
Studies of absorption spectra of carbon dioxide at elevated pressures,
6 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere, Tomsk:, 1981, Tomsk, IAO Publishing House, 1981, Pages 110-113.
Brodbeck, C., Nguyen-Van-Thanh, Bouanich, J.-P., Boulet, C., Jean-Louis, A., Bezard, B., De Bergh, C.,
Measurements of pure CO2 absorption at high densities near 2.3 μm,
Journal of Geophysical Research, 1991, Volume 96E, Issue 2, Pages 174 97,
DOI: 10.1029/91JE01680.
Annotation
Thermal emission from the deep atmosphere of Venus can be detected on the nightside around 2.3 μm. The analysis of this radiation requires a reliable knowledge of the absorption in the far wings of the nearby allowed CO2 bands and of the absorption due to collision‐induced bands. We measured absorption coefficients for pure CO2 at pressures varying from 30 to 60 bars in the frequency range 3910–4570 cm−1 at 297.5 K. Values between 1.0 and 1.6 × 10−7 cm−1 amagat−2 are found in the 4100–4500 cm−1 interval where emission from the Venus nightside occurs. The comparison of experimental results with synthetic spectra calculated from a line by line code demonstrates that the Lorentzian line shape strongly overestimates the observed absorption, whereas the use of a χ factor extrapolated from the 3800–4000 cm−1 region does not provide enough opacity.
M. V. Tonkov, N. N. Filippov, V. V. Bertsev, J. P. Bouanich, Nguyen Van-Thanh, C. Brodbeck, J. M. Hartmann, C. Boulet, F. Thibault, and R. Le Doucen,
Measurements and empirical modeling of pure CO2 absorption in the 2.3-νm region at room temperature: far wings, allowed and collision-induced bands,
Applied Optics, 1996, Volume 35, Pages 4863-4870,
DOI: 10.1364/AO.35.004863, https://doi.org/10.1364/AO.35.004863.
Annotation
Measurements of pure CO2 absorption in the 2.3-μm region are presented. The 3800–4700-cm−1 range has been investigated at room temperature for pressures in the 10–50-atm range by using long optical paths. Phenomena that contribute to absorption are listed and analyzed, including the contribution of far line wings as well as those of the central region of both allowed and collision-induced absorption bands. The presence of simultaneous transitions is also discussed. Simple and practical approaches are proposed for the modeling of absorption, which include a line-shape correction factor χ that extends to approximately 600 cm−1 from line centers.
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
S.A. Tashkun, V. I. Perevalov, J-L. Teffo, A. D. Bykov and N. N. Lavrentieva,
CDSD-1000, the high-temperature carbon dioxide spectroscopic databank,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2003, Volume 82, Issue 1, Pages 165-196,
DOI: 10.1016/S0022-4073(03)00152-3.
Annotation
We present a high-temperature version, CDSD-1000, of the carbon dioxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air-broadened half-widths) of the four most abundant isotopic species of the carbon dioxide molecule. The reference temperature is Tref=1000°K and the intensity cutoff is Icut=10−27 cm−1/moleculecm−2. More than 3 million lines covering the 260–8310, 418–2454, 394–4662, and 429–2846 cm−1 spectral ranges for 12C16O2, 13C16O2, 12C16O18O, and 12C16O17O, respectively, are included in CDSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonians and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulations of several low- and medium-resolution high-temperature (T=800-3000 K) spectra have been performed in order to validate the databank. Comparisons of CDSD-1000 with other high-temperature databanks HITEMP, HITELOR, and EM2C are also given. CDSD-1000 is able to reproduce observed spectra in a more satisfactory way than the high-resolution databank HITEMP for temperatures higher than 1000°K. The databank is useful for studying high-temperature radiative properties of CO2. CDSD-1000 is freely accessible via the Internet.
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
R.A. Toth, L.R. Brown, C.E. Miller, V. Malathy Devi and D.Chris Benner,
Spectroscopic database of CO2 line parameters: 4300–7000 cm-1,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2008, Volume 109, Issue 6, Pages 906-921,
DOI: 10.1016/j.jqsrt.2007.12.004.
Annotation
A new spectroscopic database for carbon dioxide in the near infrared is presented to support remote sensing of the terrestrial planets (Mars, Venus and the Earth). The compilation contains over 28,500 transitions of 210 bands from 4300 to 7000 cm−1 and involves nine isotopologues: 16O12C16O (626), 16O13C16O (636), 16O12C18O (628), 16O12C17O (627), 16O13C18O (638), 16O13C17O (637), 18O12C18O (828), 17O12C18O (728) and 18O13C18O (838). Calculated line positions, line intensities, Lorentz half-width and pressure-induced shift coefficients for self- and air-broadening are taken from our recent measurements and are presented for the Voigt molecular line shape. The database includes line intensities for 108 bands measured using the McMath–Pierce Fourier transform spectrometer located on Kitt Peak, Arizona. The available broadening parameters (half-widths and pressure-induced shifts) of 16O12C16O are applied to all isotopologues. Broadening coefficients are computed using empirical expressions that have been fitted to the experimental data. There are limited data for the temperature dependence of widths and so no improvement has been made for those parameters. The line intensities included in the catalog vary from 4×10−30 to 1.29×10−21 cm−1/(molecule cm−2) at 296 K. The total integrated intensity for this spectral interval is 5.9559×10−20 cm−1/(molecule cm−2) at 296 K.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
Nikolai N. Filippov, Ruslan E. Asfin, Tatiana N. Sinyakova, Ivan M. Grigoriev, Tatiana M. Petrova, Alexandr M. Solodov, Alexandr A. Solodov and Jeanna V. Buldyreva,
Experimental and theoretical studies of CO2 spectra for planetary atmosphere modelling: region 600–9650 cm−1 and pressures up to 60 atm,
Physical Chemistry Chemical Physics, 2013, Volume 15, Pages 13826-13834,
DOI: 10.1039/C3CP50279A.
Annotation
Extensive experimental studies of room-temperature carbon dioxide absorption coefficients are reported for a wide range of wavenumbers and pressures requested in atmospheric spectra modelling. The quality of measurements is optimised by the use of two complementary setups with long- and short-path optical cells for low and high gas densities, respectively. The recorded spectra provide a representative picture of band-shape evolutions from gaseous to nearly liquid phases of CO2 and enable a theoretical analysis of line-mixing effects. Various kinds of vibrational bands (Σ←Σ, Π←Σ as well as Π←Π transitions) are modelled using a specific, non-Markovian in the general case, approach of Energy-Corrected Sudden type which is based on the symmetric relaxation matrix and, in contrast to the standard ECS model used for infrared absorption calculations, ensures automatically the fundamental relations of detailed balance and double-sided sum rules. Moreover, this method properly accounts for the vibrational angular momenta of the initial and final molecular states and allows including Coriolis resonances via the usual Herman-Wallis factors in the dipole transition moments. With a set of ECS parameters previously obtained for isotropic and anisotropic Raman spectra modelling, completely neglected imaginary part of the relaxation operator and a simple change in the tensorial rank to get the dipole absorption case in the working formulae, the computed spectra reproduce quite correctly the vibrotational band shapes up to 20 amagat without any additional parameter. An empirical correction factor tentatively introduced to account globally for the Coriolis effects on the relaxation matrix leads to better matches with high-density band shapes but its role merits further studies with an accurately modelled imaginary part of the relaxation matrix.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Yu.I. Baranov,
On the significant enhancement of the continuum-collision induced absorption in H2O+CO2 mixtures,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2016, Volume 175, Pages 100-106,
DOI: 10.1016/j.jqsrt.2016.02.017, https://doi.org/10.1016/j.jqsrt.2016.02.017.
Annotation
The IR spectra of water vapor–carbon dioxide mixtures as well as the spectra of pure gas samples have been recorded using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm−1 in order to explore the effect of colliding CO2 and H2O molecules on their continuum absorptions. The sample temperatures were 294°, 311°, 325° and 339°K. Measurements have been conducted at several different water vapor partial pressures depending on the cell temperature. Carbon dioxide pressures were kept close to the three values of 103, 207 and 311 kPa (1.02, 2.04 and 3.07 atm). The path length used in the study was 100 m. It was established that, in the region around 1100 cm−1, the continuum absorption coefficient CH2O+CO2 is about 20 times stronger than the water–nitrogen continuum absorption coefficient CH2O+N2. On the other hand, in the far wing region (2500 cm−1) of the ν3 CO2 fundamental band, the binary absorption coefficient CCO2+H2O appears to be about one order of magnitude stronger than the absorption coefficient in CCO2+CO2 pure carbon dioxide. The continuum interpretation and the main problem of molecular band shape formation are discussed in light of these experimental facts.
D. Mondelain, S. Vasilchenko, P. Čermák, S. Kassi, A. Campargue,
The CO2 absorption spectrum in the 2.3 µm transparency window by high sensitivity CRDS: (II) Self-absorption continuum,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2017, Volume 187, Pages 38–43,
DOI: 10.1016/j.jqsrt.2016.09.003, http://dx.doi.org/10.1016/j.jqsrt.2016.09.003.
Annotation
The CO2 absorption continuum near 2.3 µm is determined for a series of sub atmospheric pressures (250–750 Torr) by high sensitivity Cavity Ring Down Spectroscopy. An experimental procedure consisting in injecting successively a gas flow of CO2 and synthetic air, keeping constant the gas pressure in the CRDS cell, has been developed. This procedure insures a high stability of the spectra baseline by avoiding changes of the optical alignment due to pressure changes.
The CO2 continuum was obtained as the difference between the CO2 absorption coefficient and a local lines simulation using a Voigt profile truncated at ±25 cm−1. Following the results of the preceding analysis of the CO2 rovibrational lines (Vasilchenko S et al. J Quant Spectrosc Radiat Transfer 10.1016/j.jqsrt.2016.07.002, a CO2 line list with intensities obtained by variational calculations and empirical line positions was preferred to the HITRAN line list. A quadratic pressure dependence of the absorption continuum is observed, with an average binary absorption coefficient increasing from 2 to 4×10−8 cm−1 amagat−2 between 4320 and 4380 cm−1.
The obtained continuum is found in good agreement with a previous measurement using much higher densities (20 amagat) and a low resolution grating spectrograph and is consistent with values currently used in the analysis of Venus spectra.
N. I. Moskalenko, O. V. Zotov, Yu. A. Il’in, M. S. Khamidullina Russian Physics Journal · July , DOI: , Complex Investigation of the Absorption and Emission Spectra of Carbon Dioxide,
Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, 2017, Volume 59, no. 12, Pages 2017-2024,
DOI: 10.1007/s11182-017-1009-7.
Annotation
Absorption and emission spectra of carbon dioxide are measured and analyzed for temperatures 220–2500 K in the spectral range 1–25 μm. Intensities and half-widths of the spectral lines are determined and hightemperature atlas of the spectral lines’ parameters is compiled. Based on the developed mathematical model, the parameters of spectral transmission functions of СО2 are obtained at different temperatures in the vibration-rotation and pressure-induced bands of СО2. Practical application of the obtained radiative characteristics is considered for solving problems of radiative heat exchange in planetary atmospheres and high-temperature media and designing optoelectronic systems intended for aero carriers monitoring.
T.G. Adiks, G.V. Tchlenova and A.A. Vigasin,
On the influence of van der waals association on IR absorption band shapes of highly compressed carbon dioxide,
Infrared Physics, 1989, Volume 29, Issue 24, Pages 575-582,
DOI: 10.1016/0020-0891(89)90100-0, https://doi.org/10.1016/0020-0891(89)90100-0.
Annotation
An attempt is made to describe the observed band shape deformations of a number of CO2 vibro-rotational absorption bands (1.4, 1.6 and 2.0 pm) making use of the ideas on the associative equilibrium in compressed gas. It is shown that the model of monomer-dimer equilibrium permits representation of the IR absorption band shapes within an experimental accuracy up to 5.0 MPa. The comparison of the found dimeric band shape with the calculated synthetic spectra of P- and T-isomers is also discussed.
Москаленко Н.И., Ильин Ю.А., Паржин С.Н., Родионов Л.В.,
Индуцированное давлением поглощение ИК-излучения в атмосферах,
Известия АН СССР. Серия Физика атмосферы и океана, 1979, Т. 15, № 9, Страницы 912-919.
Аннотация
Moskalenko N.I., Ilyin Yu.A., Parzhin S.N., Rodionov L.V., Pressure-induced absorption of infrared radiation in atmospheres, Izvestia of the Academy of Sciences of the USSR. Series Physics of Atmosphere and Ocean, 1979, Vol. 15, No. 9, Pages 912-919.
Brodbeck, C., Nguyen-Van-Thanh, Bouanich, J.-P., Boulet, C., Jean-Louis, A., Bezard, B., De Bergh, C.,
Measurements of pure CO2 absorption at high densities near 2.3 μm,
Journal of Geophysical Research, 1991, Volume 96E, Issue 2, Pages 174 97,
DOI: 10.1029/91JE01680.
Annotation
Thermal emission from the deep atmosphere of Venus can be detected on the nightside around 2.3 μm. The analysis of this radiation requires a reliable knowledge of the absorption in the far wings of the nearby allowed CO2 bands and of the absorption due to collision‐induced bands. We measured absorption coefficients for pure CO2 at pressures varying from 30 to 60 bars in the frequency range 3910–4570 cm−1 at 297.5 K. Values between 1.0 and 1.6 × 10−7 cm−1 amagat−2 are found in the 4100–4500 cm−1 interval where emission from the Venus nightside occurs. The comparison of experimental results with synthetic spectra calculated from a line by line code demonstrates that the Lorentzian line shape strongly overestimates the observed absorption, whereas the use of a χ factor extrapolated from the 3800–4000 cm−1 region does not provide enough opacity.
M. V. Tonkov, N. N. Filippov, V. V. Bertsev, J. P. Bouanich, Nguyen Van-Thanh, C. Brodbeck, J. M. Hartmann, C. Boulet, F. Thibault, and R. Le Doucen,
Measurements and empirical modeling of pure CO2 absorption in the 2.3-νm region at room temperature: far wings, allowed and collision-induced bands,
Applied Optics, 1996, Volume 35, Pages 4863-4870,
DOI: 10.1364/AO.35.004863, https://doi.org/10.1364/AO.35.004863.
Annotation
Measurements of pure CO2 absorption in the 2.3-μm region are presented. The 3800–4700-cm−1 range has been investigated at room temperature for pressures in the 10–50-atm range by using long optical paths. Phenomena that contribute to absorption are listed and analyzed, including the contribution of far line wings as well as those of the central region of both allowed and collision-induced absorption bands. The presence of simultaneous transitions is also discussed. Simple and practical approaches are proposed for the modeling of absorption, which include a line-shape correction factor χ that extends to approximately 600 cm−1 from line centers.
M. V. Tonkov, N. N. Filippov, Yu. M. Timofeyev and A. V. Polyakov,
A simple model of the line mixing effect for atmospheric applications: Theoretical background and comparison with experimental profiles,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1996, Volume 56, Issue 5, Pages 783-795,
DOI: 10.1016/S0022-4073(96)00113-6.
Annotation
We propose a new empirical method of band shape calculations which takes into account line mixing effects. The proposed shape is based on the strong collision model with attenuated interbranch coupling. Apart from the conventional set of spectral line parameters one needs only one additional parameter to account for line mixing effects in band profile calculations. This parameter depends on the perturbing gas type. It is the same for all molecular infrared absorption bands. The new shapes are shown to be successful in representing the measured absorption bands of CO2 in nitrogen (v2, v3, v2 + 2v3, 2v2 − v2, and 2v1 − v2) and the 3.6 μm band of O3 in nitrogen.
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
S.A. Tashkun, V. I. Perevalov, J-L. Teffo, A. D. Bykov and N. N. Lavrentieva,
CDSD-1000, the high-temperature carbon dioxide spectroscopic databank,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2003, Volume 82, Issue 1, Pages 165-196,
DOI: 10.1016/S0022-4073(03)00152-3.
Annotation
We present a high-temperature version, CDSD-1000, of the carbon dioxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air-broadened half-widths) of the four most abundant isotopic species of the carbon dioxide molecule. The reference temperature is Tref=1000°K and the intensity cutoff is Icut=10−27 cm−1/moleculecm−2. More than 3 million lines covering the 260–8310, 418–2454, 394–4662, and 429–2846 cm−1 spectral ranges for 12C16O2, 13C16O2, 12C16O18O, and 12C16O17O, respectively, are included in CDSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonians and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulations of several low- and medium-resolution high-temperature (T=800-3000 K) spectra have been performed in order to validate the databank. Comparisons of CDSD-1000 with other high-temperature databanks HITEMP, HITELOR, and EM2C are also given. CDSD-1000 is able to reproduce observed spectra in a more satisfactory way than the high-resolution databank HITEMP for temperatures higher than 1000°K. The databank is useful for studying high-temperature radiative properties of CO2. CDSD-1000 is freely accessible via the Internet.
Domanskaya A. V., Filippov N. N., Grigorovich N. M., Tonkov M. V,
Modelling of the rotational relaxation matrix in line-mixing effect calculations,
Molecular Physics, 2004, Volume 102, Issue 16-17, Pages 1843-1850.
Annotation
In this work we discuss and compare the properties of empirical rotational relaxation matrices, which are responsible for the line-mixing effects in IR absorption in the gas phase. The energy-corrected sudden approximation, the strong collision model, the adjusted branch coupling (ABC) model, and the varied collision efficiency (VCE) model are considered. The ABC and VCE models are applied to the band shape calculations for CO2 and CF4 spectra in rare gas mixtures. The VCE model proved to be better for this purpose.
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
J. Lamouroux, H. Tran, A.L. Laraia, R.R. Gamache, L.S. Rothman, I.E. Gordon, J.-M. Hartmann,
Updated database plus software for line-mixing in CO2 infrared spectra and their test using laboratory spectra in the 1.5–2.3 μm region,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2010, Volume 111, Issue 15, Pages 2321-2331,
DOI: 10.1016/j.jqsrt.2010.03.006.
Annotation
XVIth Symposium on High Resolution Molecular Spectroscopy (HighRus-2009)
In a previous series of papers, a model for the calculation of CO2-air absorption coefficients taking line-mixing into account and the corresponding database/software package were described and widely tested. In this study, we present an update of this package, based on the 2008 version of HITRAN, the latest currently available. The spectroscopic data for the seven most-abundant isotopologues are taken from HITRAN. When the HITRAN data are not complete up to J″=70, the data files are augmented with spectroscopic parameters from the CDSD-296 database and the high-temperature CDSD-1000 if necessary. Previously missing spectroscopic parameters, the air-induced pressure shifts and CO2 line broadening coefficients with H2O, have been added. The quality of this new database is demonstrated by comparisons of calculated absorptions and measurements using CO2 high-pressure laboratory spectra in the 1.5–2.3 μm region. The influence of the imperfections and inaccuracies of the spectroscopic parameters from the 2000 version of HITRAN is clearly shown as a big improvement of the residuals is observed by using the new database. The very good agreements between calculated and measured absorption coefficients confirm the necessity of the update presented here and further demonstrate the importance of line-mixing effects, especially for the high pressures investigated here. The application of the updated database/software package to atmospheric spectra should result in an increased accuracy in the retrieval of CO2 atmospheric amounts. This opens improved perspectives for the space-borne detection of carbon dioxide sources and sinks.
R.A. Toth, L.R. Brown, C.E. Miller, V. Malathy Devi and D.Chris Benner,
Spectroscopic database of CO2 line parameters: 4300–7000 cm-1,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2008, Volume 109, Issue 6, Pages 906-921,
DOI: 10.1016/j.jqsrt.2007.12.004.
Annotation
A new spectroscopic database for carbon dioxide in the near infrared is presented to support remote sensing of the terrestrial planets (Mars, Venus and the Earth). The compilation contains over 28,500 transitions of 210 bands from 4300 to 7000 cm−1 and involves nine isotopologues: 16O12C16O (626), 16O13C16O (636), 16O12C18O (628), 16O12C17O (627), 16O13C18O (638), 16O13C17O (637), 18O12C18O (828), 17O12C18O (728) and 18O13C18O (838). Calculated line positions, line intensities, Lorentz half-width and pressure-induced shift coefficients for self- and air-broadening are taken from our recent measurements and are presented for the Voigt molecular line shape. The database includes line intensities for 108 bands measured using the McMath–Pierce Fourier transform spectrometer located on Kitt Peak, Arizona. The available broadening parameters (half-widths and pressure-induced shifts) of 16O12C16O are applied to all isotopologues. Broadening coefficients are computed using empirical expressions that have been fitted to the experimental data. There are limited data for the temperature dependence of widths and so no improvement has been made for those parameters. The line intensities included in the catalog vary from 4×10−30 to 1.29×10−21 cm−1/(molecule cm−2) at 296 K. The total integrated intensity for this spectral interval is 5.9559×10−20 cm−1/(molecule cm−2) at 296 K.
Bharadwaj S.P., Modest M.F.,
Medium resolution transmission measurements of CO2 at high temperature – an update,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2007, Volume 103, Pages 146-155,
DOI: 10.1016/j.jqsrt.2006.05.011, https://doi.org/10.1016/j.jqsrt.2006.05.011.
Annotation
The current work presents updated measurements of narrow-band transmission for the 2.0, 2.7 and 4.3 μm bands of CO2 at temperatures of up to 1550 K. In addition, measurements for 15 μm the band of CO2 are also presented for the first time. Data were collected with an improved drop tube design (as compared to the earlier measurements) and an FTIR-spectrometer. The measured data were compared with the CDSD and HITEMP databases, as well as with previous data obtained from the old drop tube apparatus. The new data have less uncertainties at extreme temperatures than the old data and eliminate some of the problems associated with subtraction of the emission signal with the old apparatus. The data show minor discrepancies with the high-resolution databases, particularly with HITEMP at higher temperatures, but in general agreement is good.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
Nikolai N. Filippov, Ruslan E. Asfin, Tatiana N. Sinyakova, Ivan M. Grigoriev, Tatiana M. Petrova, Alexandr M. Solodov, Alexandr A. Solodov and Jeanna V. Buldyreva,
Experimental and theoretical studies of CO2 spectra for planetary atmosphere modelling: region 600–9650 cm−1 and pressures up to 60 atm,
Physical Chemistry Chemical Physics, 2013, Volume 15, Pages 13826-13834,
DOI: 10.1039/C3CP50279A.
Annotation
Extensive experimental studies of room-temperature carbon dioxide absorption coefficients are reported for a wide range of wavenumbers and pressures requested in atmospheric spectra modelling. The quality of measurements is optimised by the use of two complementary setups with long- and short-path optical cells for low and high gas densities, respectively. The recorded spectra provide a representative picture of band-shape evolutions from gaseous to nearly liquid phases of CO2 and enable a theoretical analysis of line-mixing effects. Various kinds of vibrational bands (Σ←Σ, Π←Σ as well as Π←Π transitions) are modelled using a specific, non-Markovian in the general case, approach of Energy-Corrected Sudden type which is based on the symmetric relaxation matrix and, in contrast to the standard ECS model used for infrared absorption calculations, ensures automatically the fundamental relations of detailed balance and double-sided sum rules. Moreover, this method properly accounts for the vibrational angular momenta of the initial and final molecular states and allows including Coriolis resonances via the usual Herman-Wallis factors in the dipole transition moments. With a set of ECS parameters previously obtained for isotropic and anisotropic Raman spectra modelling, completely neglected imaginary part of the relaxation operator and a simple change in the tensorial rank to get the dipole absorption case in the working formulae, the computed spectra reproduce quite correctly the vibrotational band shapes up to 20 amagat without any additional parameter. An empirical correction factor tentatively introduced to account globally for the Coriolis effects on the relaxation matrix leads to better matches with high-density band shapes but its role merits further studies with an accurately modelled imaginary part of the relaxation matrix.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
T.G. Adiks, G.V. Tchlenova and A.A. Vigasin,
On the influence of van der waals association on IR absorption band shapes of highly compressed carbon dioxide,
Infrared Physics, 1989, Volume 29, Issue 24, Pages 575-582,
DOI: 10.1016/0020-0891(89)90100-0, https://doi.org/10.1016/0020-0891(89)90100-0.
Annotation
An attempt is made to describe the observed band shape deformations of a number of CO2 vibro-rotational absorption bands (1.4, 1.6 and 2.0 pm) making use of the ideas on the associative equilibrium in compressed gas. It is shown that the model of monomer-dimer equilibrium permits representation of the IR absorption band shapes within an experimental accuracy up to 5.0 MPa. The comparison of the found dimeric band shape with the calculated synthetic spectra of P- and T-isomers is also discussed.
The shapes of the extreme wings of self-broadened CO2(lines have been investigated)in three spectral regions near 7000, 3800, and 2400 cm-1. Absorption measurements have been made on the high-wavenumber sides of band heads where much of the absorption by samples at a few atm is due to the extreme wings of strong lines whose centers occur below the band heads. New information has been obtained about the shapes of self-broadened CO2 lines as well as CO2 lines broadened by N2, O2, Ar, He, and H2. Beyond a few cm-1 from the line centers, all of the lines absorb less than Lorentz-shaped lines having the same half-widths. The deviation from the Lorentz shape decreases with increasing wavenumber, from one of the three spectral regions to the next. The absorption by the wings of H2- and He-broadened lines is particularly low, and the absorption decreases with increasing temperature at a rate faster than predicted by existing theories.
Гальцев А.П.,
Определение функции корреляции флуктуаций частоты по измерениям поглощения в далеких крыльях линий,
Оптика и спектроскопия, 1974, Volume 36, Issue 2, Pages 309-314.
Гальцев А.П., Осипов В.М., Шереметьева Т.А.,
Определение параметров контура линий СО2 методом минимизации,
Известия АН СССР. Серия Физика атмосферы и океана, 1973, Volume 9, no. 11, Pages 1195-1200.
Войцеховская О.К., Л.И.Несмелова. О.Б.Родимова, О.Н.Сулакшина, Ю.С.Макушкин, С.Д.Творогов,
Коэффициент поглощения света в крыле полосы 1.4 мкм СО2,
6 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 2.,
Томск: ИОА СО АН СССР, 1981, Страницы 16-19.
Телегин Г.В., Фомин В.В.,
Расчет коэффициента поглощения в крыльях полос СО2,
5 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 3.,
Томск: ИОА СО АН СССР, Издательство ИОА, 1979, Pages 152-156.
Annotation
Telegin G.V., Fomin V.V.,
Calculation of the absorption coefficient in the wings of CO2 bands,
Proceedings of 5 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere. Part 3., Tomsk: IOA SO AN SSSR, IOA Publishing House, 1979, Pages 152-156.
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов,
Методика расчета поглощения излучения в узких спектральных интервалах колебательно-вращательных спектров молекул,
III Всесоюзное совещание по атмосферной оптике и актинометрии. Тезисы докладов, часть II.,
Томск, Издательство ИОА, 1983, Страницы 155-157.
Аннотация
Nesmelova L.I., O.B. Rodimova, S.D. Tvorogov
Method for calculating radiation absorption in narrow spectral intervals of vibrational-rotational spectra of molecules
III All-Union Meeting on Atmospheric Optics and Actinometry. Abstracts, part II. Tomsk, 1983. P. 155-157.
С.Д.Творогов, О.Б.Родимова, Несмелова Л.И.,
Спектроскопия крыльев колебательно-вращательных линий газов,
XIX Всесоюзный съезд по спектроскопии. Тезисы докладов. Часть II. Спектроскопия простых молекул.,
Томск, Издательство ИОА, 1983, Страницы 254-256.
Аннотация
S.D. Tvorogov, O.B. Rodimova, Nesmelova L.I.
Spectroscopy of the wings of vibrational-rotational gas lines XIX All-Union Congress on Spectroscopy.
Abstracts of reports. Part II. Spectroscopy of simple molecules. Tomsk. 1983.S. 254-256
Несмелова Л.И., О.Б.Родимова, С.Д.Творогов, О.К.Войцеховская, Ю.С.Макушкин, О.Н.Сулакшина,
Интерпретация спектров поглощения углекислого газа за кантами полос,
6 Всесоюзн. Симпозиум по молекулярной спектроскопии высокого и сверхвысокого разрешения, тезисы докладов, Томск, 1982, ч.2,
Томск, Издательство ИОА, 1982, Страницы 53-61.
Аннотация
Nesmelova L.I., O.B. Rodimova, S.D. Tvorogov, O.K. Voitsekhovskaya, Yu.S. Makushkin, O. N. Sulakshina,
Interpretation of absorption spectra of carbon dioxide behind the edges of the bands,
in: 6 All-Union. Symposium on molecular spectroscopy of high and ultra-high resolution, abstracts, Tomsk, 1982, part 2, pp.53-61.
Тарабухин В.М.., Тонков М.В.,
Экспериментальное исследование спектрального обмена в полосе 3ν3 СО2,
VII Всесоюзный симпозиум по молекулярной спектроскопии высокого и сверхвысокого разрешения, Томск: ИОА, Часть III, 1986,
Томск: ИОА СО АН СССР, Издательство ИОА, 1986, Страницы 232-235.
Аннотация
Tarabukhin V.M., Tonkov M.V.
Experimental study of spectral exchange in the 3ν3 CO2 band.
in the book: VII All-Union Symposium on Molecular Spectroscopy of High and Ultra-High Resolution, Tomsk: IAO, Part III, 1986, pp. 232-235.
Grigorev, I.M., Tarabukhin, V.M., Tonkov, M.V.,
Singularities of the CO2 absorption spectrum in the region of the 3ν3 band edge,
Optics and Spectroscopy, 1985, Volume 58, Pages 147.
J. Boissoles, F. Thibault, R. Le Doucen, V. Menoux, and C. Boulet,
Line mixing effects in the 0003–0000 band of CO2 in helium. III. Energy corrected sudden simultaneous fit of linewidths and near wing profile,
Journal of Chemical Physics, 1994, Volume 101, Issue 8,
DOI: 10.1063/1.468348, http://link.aip.org/link/JCPSA6/v101/i8/p6552/s1.
Annotation
Line coupling induced by collisions leads to drastic modifications of the spectral profile of the 0003–0000 of CO2 pressurized by helium. Calculation of these modifications have been performed by using two recent energy corrected sudden (ECS) formalisms. The two formulations lead to theoretical predictions rather similar and in good agreement with the available data over extended ranges of frequency and perturber pressure. It has been shown that a simultaneous fit of the pressure broadened linewidths and the near wing profile allows a more accurate determination of the basic ECS parameters. For that purpose, it has been necessary to extend the measurement of the broadened widths to high J values (up to J≊90).
J. Boissoles, R. Le Doucen, F. Thibault and C. Boulet,
The 3v3 band of CO2—influence of the pressurized perturber gas,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1994, Volume 52, Issue 3-4, Pages 361-366,
DOI: 10.1016/0022-4073(94)90166-X.
Annotation
The modification of the shape of the 3v3 vibration-rotation band of CO2 by different perturbing gases (CO2, He, Ar, N2) has been studied at room temperature for a wide range of pressures (up to 140 atm) using a Fourier transform interferometer. Important narrowing effects in the R branch are observed.
F. Thibault, J. Boissoles, R. Le Doucen, and V. Menoux, C. Boulet,
Line mixing effects in the 00°3–00°0 band of CO2 in helium. I. Experiment,
Journal of Chemical Physics, 1994, Volume 100, Issue 1, Pages 210,
DOI: 10.1063/1.466981.
Annotation
The shape of the 0003–0000 CO2 band in helium has beeninvestigated at room temperature over an extended range of perturberpressures (0–140 atm). Various and strong deviations from an additivesuperposition of Lorentzian lines have been observed, due to importantline mixing effects enhanced by the specific structure of theR branch in this band.
J. M. Hartmann and F. L’Haridon,
Simple modeling of line‐mixing effects in IR bands. I. Linear molecules: Application to CO2,
Journal of Geophysical Research: Planets, 1995, Volume 103, Pages 6467,
DOI: 10.1063/1.470424, https://doi.org/10.1063/1.470424.
Annotation
A simple approach is developed in order to model the influence of collisions on the shape of infrared absorption by linear molecules. It accounts for line‐mixing effects within, as well as between, the different branches (P, Q, R) of the band. It is based on use of the strong collision model, of a classical representation of rotational levels, and of the rigid rotor approximation. The absorption coefficient then has a very simple analytical expression; its wave number and pressure dependencies are computed by using eight parameters which depend on the considered vibrational transition, the temperature, and the nature of the perturber only. These quantities are band‐averaged values of the detailed spectroscopic and collisional parameters of the molecular system. Tests of the model are presented in the ν3 and 3ν3 bands of CO2 perturbed by He and Ar at elevated pressures. They demonstrate the accuracy of our approach in accounting for the effects of collisions on the spectral shape in a wide density range; indeed, the superposition of Lorentzian individual lines at low pressure, as well as the collapse (narrowing) of the band at very high pressure are satisfactory predicted.
N. N. Filippov, J. -P. Bouanich, J. -M. Hartmann, L. Ozanne, C. Boulet, M. V. Tonkov, F. Thibault, R. Le Doucen,
Line-mixing effects in the 3v3 band of CO2 perturbed by Ar,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1996, Volume 55, Issue 3, Pages 307-320,
DOI: doi:10.1016/0022-4073(95)00170-0.
Annotation
Measurements of absorption coefficients in the 3v3 band of CO2 at 1.44 μm perturbed by Ar up to 146 bar have been analyzed by using two line-mixing theoretical calculations within the impact approximation. In the first approach, the relaxation operator is treated semi-classically with adiabatic corrections. In the second, the relaxation operator is modelled with the Energy Corrected Sudden (ECS) approximation associated with a power fitting law providing the basic rotational state-to-state rates. Although the line-coupling spectroscopic cross-sections of the two models are significantly different, they both lead to satisfactory agreement with bandshapes at moderate densities (< 100 Amagat). Significant deviations between experimental and calculated spectra appear at higher densities. They are mainly attributed to the probable breakdown of the impact and binary collision approximations and to a number of reasons including an incorrect ECS calculation of the interbranch coupling, the nonlinear density dependence due to the finite volume of the molecules, and the neglect of the unknown imaginary part of the off-diagonal elements in the calculated relaxation matrix.
B. Khalil, O. Cisse, G. Moreau, F. Thibault, R. Le Doucen and J. Boissoles,
Line mixing and line broadening in CO2 bands perturbed by helium at 193 K,
Chemical Physics Letters, 1996, Volume 263, Issue 6, Pages 811-816,
DOI: 10.1016/S0009-2614(96)01276-6.
Annotation
The ν2 and 3ν3 bands of CO2 in helium baths at 193 K have studied with a Fourier transform interferometer. The behavior of the band shapes has been explored at moderate densities. The energy corrected sudden (ECS) approximation is used to model the relaxation matrix in order to account for line mixing effects. The basis cross-sections were calculated with the simple power law (P). Computed spectra are in good agreement with the observed ones. Measured broadening coefficients are also comparable with the ones derived from the ECS-P model.
Filippov N.N., Bouanich J.P., Boulet C., Tonkov M.V., LeDoucen R., Thibault F.,
Collision-induced double transition effects in the 3 ν3 CO2 band wing region,
The Journal of Chemical Physics, 1997, Volume 106, Issue 6, Pages 2067-72,
DOI: 10.1063/1.473140.
Annotation
IR absorption beyond the head of the 0003–0000 (3ν3) band of CO2 near 7000 cm−1 has been analyzed. This absorption is found to consist of two comparable intensity contributions, namely, the allowed band wing and a collision-induced absorption (CIA) band. The band wing profile has been described by using a non-Markovian theory and the rotational perturbation densities for CO2–CO2 collisions, which was previously calculated from the intensity distribution in the high-frequency wing of the 0001–0000 CO2 band. The CIA component has a typical shape of CO2 CIA bands with the maximum at the double transition (0001+0002)–(0000+0000) frequency. The integrated binary coefficient of this CIA band was estimated to be B2=(1.0±0.6)×10−5 cm−2 Amagat−2. The CIA spectral moment theory has been used for the intensity calculation, which takes into account for the first time the collision-induced vibrational force field in CO2 pairs. By comparing the calculated and measured intensity for the double transition, the polarizability anisotropy matrix element for the 2ν3 band has been estimated as β20=0.26±0.08 a.u., value in reasonable agreement with an independent estimation from previous results of polarizability matrix elements of CO2.
L. Ozanne, Q. Ma, Nguyen-Van-Thanh, C. Brodbeck, J. P. Bouanich, J. M. Hartmann, C. Boulet, R. H. Tipping,
Line-mixing, finite duration of collision, vibrational shift, and non-linear density effects in the v3 and 3v3 bands of CO2 perturbed by Ar up to 1000 bar,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1997, Volume 58, Issue 2, Pages 261-277,
DOI: 10.1016/S0022-4073(97)00007-1.
Annotation
We present high-density experimental and theoretical results on CO2---Ar gas-phase absorption in the ν3 and 3ν3 infrared bands. Measurements have been made at room temperature for pressures up to 1000 bar in both the central and wing regions of the bands. A non-linear perturber density dependence of the absorption, clearly shown in the far wing, is attributed to the finite volume of the molecules. Furthermore, experiments show vibrational dephasing and narrowing effects. We have performed line-mixing computations based on the Energy Corrected Sudden approximation (ECS impact model). Significant discrepancies between experimental and calculated spectra appear when pressure increases. We then tested the influence of the finite duration of collision by using interpolations between ECS and quasi-static calculations, and we have evaluated the sensitivity of the band profiles to the interbranch mixing effects. Finally, an effective width is used in order to take other effects into account.
L. Ozanne, Nguyen-Van-Thanh, C. Brodbeck, J. P. Bouanich, J. M. Hartmann, and C. Boulet,
Line mixing and nonlinear density effects in the ν3 and 3ν3 infrared bands of CO2 perturbed by He up to 1000 bar,
Journal of Chemical Physics, 1995, Volume 102, Issue 19, Pages 7306,
DOI: 10.1063/1.469042.
Annotation
Wepresent high density experimental and theoretical results on CO2–He absorptionin the v3 and 3v3 infrared bands. Measurements have beenmade at room temperature for pressures up to 1000 barin both the central and wing regions of the bands.Computations are based on an impact line-mixing approach in whichthe relaxation operator is modeled with the energy corrected sudden(ECS) approximation. Comparisons between experimental and calculated results demonstrate theaccuracy of the ECS approach when applied to band wingsand band centers at moderate densities. On the other hand,small but significant discrepancies appear at very high pressures. Theyare attributed to a number of reasons which include nonlineardensity dependence due to the finite volume of the molecules,neglected contributions of vibration to the relaxation matrix, and incorrectmodeling of interbranch mixing.
N.N. Filippov and M.V. Tonkov,
Semiclassical analysis of line mixing in the infrared bands of CO and CO2,
Journal of Quantitative Spectroscopy and Radiation Transfer, 1993, Volume 50, Issue 1, Pages 111-125,
DOI: 10.1016/0022-4073(93)90134-4.
Annotation
A method of calculation of an i.r. band shape suitable for overlapping lines has been proposed. Line mixing effects are considered using an impact model based on the Burshtein-Temkin theory which treats the rotational motion of molecules classically. The kernel of the integral equation defining spectral function is used to calculate the rotational relaxation matrix. For a linear-molecule-atom pair with repulsive interaction, the ovaloid-sphere collision model was found to be applicable for calculation of the angular velocity changing distribution. The parameters of the model are estimated using ab initio intermolecular potentials. The developed method is applied to CO and CO2 i.r. band shape calculations.
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
J. Boissoles, F. Thibault, R. Le Doucen, V. Menoux, and C. Boulet,
Line mixing effects in the 00°3–00°0 band of CO2 in helium. II. Theoretical analysis,
Journal of Chemical Physics, 1994, Volume 100, Issue 1, Pages 215,
DOI: 10.1063/1.466989, http://link.aip.org/link/JCPSA6/v100/i1/p215/s1.
Annotation
In paper I of this series, important deviations from an additive superposition of Lorentzian profiles were experimentally evidenced in the 00°3–00°0 band of CO2 in He. All the observed deviations are explained by the collision‐induced line mixing effects which schematically transfer intensity from the wing of the band to its central part. The IOS approximation has been found to be insufficient while, the ECS approximation leads to theoretical predictions in good agreement with the experimental data over extended ranges of frequency and perturber pressure. However it must be emphasized that it has been necessary to resort to the method in current use for the determination of the fundamental rates, an ad hoc adjustement starting from the observed linewidths.
Golovko V. F.,
Calculation of carbon dioxide absorption spectra in wide spectral regions,
Atmospheric and Oceanic Optics, 2001, Volume 14, Issue 9, Pages 807-812.
Annotation
A somewhat unexpected hypothesis of the Fermi distribution of photon fluctuations connected with a two-level system is chosen to explain the exponential shape of the absorption line profile in its far wing. A preference is given to studies of the properties of direct interaction between radiation and a matter being in chaotic thermal motion, rather than to the influence of intermolecular interaction on the line shape. A simple exponential form for the far wings of absorption lines is obtained. Examples of modeling absorption in wide spectral regions from 442 to 9648 cm-1 are given for both pure CO2 and CO2-Y mixtures, where Y is one of the buffer gases: N2, H2, He, Ar, or Xe.
Afanasenko T.S., Rodin A.V.,
The effect of collisional line broadening on the spectrum and fluxes of thermal radiation in the lower atmosphere of venus,
Solar System Research, 2005, Volume 39, no. 3, Pages 187-198,
DOI: 10.1007/s11208-005-0034-1.
Annotation
The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.
J. Lamouroux, H. Tran, A.L. Laraia, R.R. Gamache, L.S. Rothman, I.E. Gordon, J.-M. Hartmann,
Updated database plus software for line-mixing in CO2 infrared spectra and their test using laboratory spectra in the 1.5–2.3 μm region,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2010, Volume 111, Issue 15, Pages 2321-2331,
DOI: 10.1016/j.jqsrt.2010.03.006.
Annotation
XVIth Symposium on High Resolution Molecular Spectroscopy (HighRus-2009)
In a previous series of papers, a model for the calculation of CO2-air absorption coefficients taking line-mixing into account and the corresponding database/software package were described and widely tested. In this study, we present an update of this package, based on the 2008 version of HITRAN, the latest currently available. The spectroscopic data for the seven most-abundant isotopologues are taken from HITRAN. When the HITRAN data are not complete up to J″=70, the data files are augmented with spectroscopic parameters from the CDSD-296 database and the high-temperature CDSD-1000 if necessary. Previously missing spectroscopic parameters, the air-induced pressure shifts and CO2 line broadening coefficients with H2O, have been added. The quality of this new database is demonstrated by comparisons of calculated absorptions and measurements using CO2 high-pressure laboratory spectra in the 1.5–2.3 μm region. The influence of the imperfections and inaccuracies of the spectroscopic parameters from the 2000 version of HITRAN is clearly shown as a big improvement of the residuals is observed by using the new database. The very good agreements between calculated and measured absorption coefficients confirm the necessity of the update presented here and further demonstrate the importance of line-mixing effects, especially for the high pressures investigated here. The application of the updated database/software package to atmospheric spectra should result in an increased accuracy in the retrieval of CO2 atmospheric amounts. This opens improved perspectives for the space-borne detection of carbon dioxide sources and sinks.
R.A. Toth, L.R. Brown, C.E. Miller, V. Malathy Devi and D.Chris Benner,
Spectroscopic database of CO2 line parameters: 4300–7000 cm-1,
Journal of Quantitative Spectroscopy and Radiation Transfer, 2008, Volume 109, Issue 6, Pages 906-921,
DOI: 10.1016/j.jqsrt.2007.12.004.
Annotation
A new spectroscopic database for carbon dioxide in the near infrared is presented to support remote sensing of the terrestrial planets (Mars, Venus and the Earth). The compilation contains over 28,500 transitions of 210 bands from 4300 to 7000 cm−1 and involves nine isotopologues: 16O12C16O (626), 16O13C16O (636), 16O12C18O (628), 16O12C17O (627), 16O13C18O (638), 16O13C17O (637), 18O12C18O (828), 17O12C18O (728) and 18O13C18O (838). Calculated line positions, line intensities, Lorentz half-width and pressure-induced shift coefficients for self- and air-broadening are taken from our recent measurements and are presented for the Voigt molecular line shape. The database includes line intensities for 108 bands measured using the McMath–Pierce Fourier transform spectrometer located on Kitt Peak, Arizona. The available broadening parameters (half-widths and pressure-induced shifts) of 16O12C16O are applied to all isotopologues. Broadening coefficients are computed using empirical expressions that have been fitted to the experimental data. There are limited data for the temperature dependence of widths and so no improvement has been made for those parameters. The line intensities included in the catalog vary from 4×10−30 to 1.29×10−21 cm−1/(molecule cm−2) at 296 K. The total integrated intensity for this spectral interval is 5.9559×10−20 cm−1/(molecule cm−2) at 296 K.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
Nikolai N. Filippov, Ruslan E. Asfin, Tatiana N. Sinyakova, Ivan M. Grigoriev, Tatiana M. Petrova, Alexandr M. Solodov, Alexandr A. Solodov and Jeanna V. Buldyreva,
Experimental and theoretical studies of CO2 spectra for planetary atmosphere modelling: region 600–9650 cm−1 and pressures up to 60 atm,
Physical Chemistry Chemical Physics, 2013, Volume 15, Pages 13826-13834,
DOI: 10.1039/C3CP50279A.
Annotation
Extensive experimental studies of room-temperature carbon dioxide absorption coefficients are reported for a wide range of wavenumbers and pressures requested in atmospheric spectra modelling. The quality of measurements is optimised by the use of two complementary setups with long- and short-path optical cells for low and high gas densities, respectively. The recorded spectra provide a representative picture of band-shape evolutions from gaseous to nearly liquid phases of CO2 and enable a theoretical analysis of line-mixing effects. Various kinds of vibrational bands (Σ←Σ, Π←Σ as well as Π←Π transitions) are modelled using a specific, non-Markovian in the general case, approach of Energy-Corrected Sudden type which is based on the symmetric relaxation matrix and, in contrast to the standard ECS model used for infrared absorption calculations, ensures automatically the fundamental relations of detailed balance and double-sided sum rules. Moreover, this method properly accounts for the vibrational angular momenta of the initial and final molecular states and allows including Coriolis resonances via the usual Herman-Wallis factors in the dipole transition moments. With a set of ECS parameters previously obtained for isotropic and anisotropic Raman spectra modelling, completely neglected imaginary part of the relaxation operator and a simple change in the tensorial rank to get the dipole absorption case in the working formulae, the computed spectra reproduce quite correctly the vibrotational band shapes up to 20 amagat without any additional parameter. An empirical correction factor tentatively introduced to account globally for the Coriolis effects on the relaxation matrix leads to better matches with high-density band shapes but its role merits further studies with an accurately modelled imaginary part of the relaxation matrix.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Климешина Т.Е., Петрова Т.М., Родимова О.Б., Солодов А.А., Солодов А.М. ,
Поглощение СО2 за кантами полос в области 8000 см–1,
Оптика атмосферы и океана, 2013, Volume 26, no. 11, Pages 925–931.
Annotation
Измерено поглощение излучения углекислым газом в области 8000 см–1, проведен расчет коэффициентов поглощения с применением асимптотической теории крыльев линий на основе подгонки к экспериментальным данным. Результаты расчета хорошо согласуются с экспериментом. Согласно теории крыльев линий поглощение в крыльях полос обусловлено крыльями сильных линий близлежащей полосы. В рамках этих представлений экспериментальные и расчетные данные о коэффициенте поглощения СО2 в крыльях двух полос в области 8000 см–1 могут являться источником сведений о форме контура спектральных линий при смещенных частотах, отвечающих нескольким десяткам полуширин. Полученные результаты подтверждают гипотезу о том, что параметры контуров в крыльях полос, отвечающих переходам с одним и тем же начальным состоянием, оказываются близкими. Выражение для контура спектральных линий при больших смещенных частотах может быть полезно для расчетов пропускания излучения в окнах прозрачности атмосфер, содержащих СО2.
Lamouroux J., Hartmann J.M., Tran H., Lavorel B , Snels M., Stefani S., Piccioni G.,
Molecular dynamics simulations for CO2 spectra. IV. Collisional line-mixing in infrared and Raman bands,
The Journal of Chemical Physics, 2013, Volume 138, Article 244310,
DOI: 10.1063/1.4811518.
Annotation
Ab initio calculations of the shapes of pure CO2 infrared and Raman bands under (pressure) conditions for which line-mixing effects are important have been performed using requantized classical molecular dynamics simulations. This approach provides the autocorrelation functions of the dipole vector and isotropic polarizability whose Fourier-Laplace transforms yield the corresponding spectra. For that, the classical equations of dynamics are solved for each molecule among several millions treated as linear rigid rotors and interacting through an anisotropic intermolecular potential. Two of the approximations used in the previous studies have been corrected, allowing the consideration of line-mixing effects without use of any adjusted parameters. The comparisons between calculated and experimental spectra under various conditions of pressure and temperature demonstrate the quality of the theoretical model. This opens promising perspectives for first principle ab initio predictions of line-mixing effects in absorption and scattering spectra of various systems involving linear molecules.
S. Kassi, A. Campargue, D. Mondelain, H. Tran,
High pressure Cavity Ring Down Spectroscopy: Application to the absorption continuum of CO2 near 1.7 µm,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2015, Volume 167, Pages 97–104,
DOI: 10.1016/j.jqsrt.2015.08.014.
Annotation
A Cavity Ring Down Spectrometer has been developed for high sensitivity absorption spectroscopy in the near infrared at pressure up to 10 bar. In order to strictly avoid perturbations of the optical alignment by pressure forces, the pre-aligned CRDS cavity is inserted inside the high pressure cell. The stability of the spectra baseline has been validated by filling the CRDS cell with Ar and N2 up to 10 bar.
We present here the first application of this CW-CRDS spectrometer to the study of the high pressure spectrum of CO2 at room temperature. The spectra were recorded between 5850 and 5960 cm−1 for a series of pressure values up to 6400 Torr. The studied spectral interval corresponds to the high energy range of the 1.75 µm transparency window of CO2 of particular interest for Venus.
The CO2 absorption coefficient at a given pressure value was obtained as the increase of the CRDS loss rate from its value at zero pressure taking into account the small contribution due to Rayleigh scattering. The CO2 absorption spectrum includes the contribution of the self broadened local rovibrational lines together with a broad and weak continuum. The CO2 continuum was obtained as the difference of the CO2 absorption coefficient and of a local lines simulation using the CO2 HITRAN line list and a truncated Voigt profile. A quadratic pressure dependence of the absorption continuum was observed, with an average binary absorption coefficient increasing smoothly from 3.7 to 11.5×10−9 cm−1 amagat−2 between 5850 and 5960 cm−1. The derived continuum shows a spectral feature located in the region of a band of 16O12C18O (present in natural abundance) which dominates the spectrum in the region. This spectral feature was found to arise from collisional interferences between local lines and quantitatively accounted for using a theoretical approach based on the impact and Energy Corrected Sudden (ECS) approximations. The impact of the chosen far wings CO2 line shape model on the retrieved continuum absorption is discussed.
T. E. Klimeshina, T. M. Petrova, O. B. Rodimova, A. A. Solodov, A. M. Solodov,
CO2 absorption in band wings in near IR,
Atmospheric and Oceanic Optics, 2015, Volume 28, Issue 5, Pages 387–393,
DOI: 10.1134/S1024856015050073, https://doi.org/10.1134/S1024856015050073.
Annotation
The CO2 absorption was measured in the 7000 and 8000 cm–1 regions. The absorption coefficients were calculated using the asymptotic line wing shape theory. Line shape parameters were found from fitting to experimental data. The calculation results agree well with the measurement data. According to the line wing theory, the absorption in the band wings is caused by the wings of strong lines of an adjacent band. Within these assumptions, experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7000 and 8000 cm–1 regions can provide information on the line shape at frequency detuning from several tens to several hundreds of half-widths. The results support the hypothesis that line shape parameters in the line wings related to transitions with the same initial state are close to each other. Deviations from a Lorentzian profile are found for some CO2 bands and turn out different for the wings of different bands
D. Mondelain, A. Campargue, Peter Čermák, Robert Gamache, S. Kassi, Sergey Tashkun, Ha Tran
, The CO2 absorption continuum by high pressure CRDS in the 1.74 µm window,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2017, Volume 203, Pages 530-537,
DOI: 10.1016/j.jqsrt.2017.02.019, https://doi.org/10.1016/j.jqsrt.2017.02.019.
Annotation
The very weak absorption continuum of CO2 is studied by Cavity Ring Down Spectroscopy in three 20 cm⁻¹ wide spectral intervals near the centre of the 1.74 µm window (5693 − 5795 cm⁻¹). For each spectral interval, a set of room temperature spectra is recorded at pressures between 0 and 10 bar thanks to a high pressure CRDS spectrometer. The absorption continuum is retrieved after subtraction of the contributions due to Rayleigh scattering and to local lines of CO2 and water (present as an impurity in the sample) from the measured extinction. Due to some deficiencies of the CO2 HITRAN2012 line list, a composite line list had to be built on the basis of the Ames calculated line list with line positions adjusted according to the Carbon Dioxide Spectroscopic Databank and self-broadening and pressure shift coefficients calculated with the Complex Robert Bonamy method. The local line contribution of the CO2 monomer is calculated using this list and a Voigt profile truncated at ±25 cm⁻¹ of the line centre. Line mixing effects were taken into account through the use of the impact and Energy Corrected Sudden approximations.
The shapes of the extreme wings of self-broadened CO2(lines have been investigated)in three spectral regions near 7000, 3800, and 2400 cm-1. Absorption measurements have been made on the high-wavenumber sides of band heads where much of the absorption by samples at a few atm is due to the extreme wings of strong lines whose centers occur below the band heads. New information has been obtained about the shapes of self-broadened CO2 lines as well as CO2 lines broadened by N2, O2, Ar, He, and H2. Beyond a few cm-1 from the line centers, all of the lines absorb less than Lorentz-shaped lines having the same half-widths. The deviation from the Lorentz shape decreases with increasing wavenumber, from one of the three spectral regions to the next. The absorption by the wings of H2- and He-broadened lines is particularly low, and the absorption decreases with increasing temperature at a rate faster than predicted by existing theories.
Гальцев А.П.,
Определение функции корреляции флуктуаций частоты по измерениям поглощения в далеких крыльях линий,
Оптика и спектроскопия, 1974, Volume 36, Issue 2, Pages 309-314.
Гальцев А.П., Осипов В.М., Шереметьева Т.А.,
Определение параметров контура линий СО2 методом минимизации,
Известия АН СССР. Серия Физика атмосферы и океана, 1973, Volume 9, no. 11, Pages 1195-1200.
Войцеховская О.К., Л.И.Несмелова. О.Б.Родимова, О.Н.Сулакшина, Ю.С.Макушкин, С.Д.Творогов,
Коэффициент поглощения света в крыле полосы 1.4 мкм СО2,
6 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 2.,
Томск: ИОА СО АН СССР, 1981, Страницы 16-19.
Телегин Г.В., Фомин В.В.,
Расчет коэффициента поглощения в крыльях полос СО2,
5 Всесоюз. Симпозиум по распространению лазерного излучения в атмосфере. Ч. 3.,
Томск: ИОА СО АН СССР, Издательство ИОА, 1979, Pages 152-156.
Annotation
Telegin G.V., Fomin V.V.,
Calculation of the absorption coefficient in the wings of CO2 bands,
Proceedings of 5 All-Union. Symposium on Propagation of Laser Radiation in the Atmosphere. Part 3., Tomsk: IOA SO AN SSSR, IOA Publishing House, 1979, Pages 152-156.
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
Golovko V. F.,
Calculation of carbon dioxide absorption spectra in wide spectral regions,
Atmospheric and Oceanic Optics, 2001, Volume 14, Issue 9, Pages 807-812.
Annotation
A somewhat unexpected hypothesis of the Fermi distribution of photon fluctuations connected with a two-level system is chosen to explain the exponential shape of the absorption line profile in its far wing. A preference is given to studies of the properties of direct interaction between radiation and a matter being in chaotic thermal motion, rather than to the influence of intermolecular interaction on the line shape. A simple exponential form for the far wings of absorption lines is obtained. Examples of modeling absorption in wide spectral regions from 442 to 9648 cm-1 are given for both pure CO2 and CO2-Y mixtures, where Y is one of the buffer gases: N2, H2, He, Ar, or Xe.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Климешина Т.Е., Петрова Т.М., Родимова О.Б., Солодов А.А., Солодов А.М. ,
Поглощение СО2 за кантами полос в области 8000 см–1,
Оптика атмосферы и океана, 2013, Volume 26, no. 11, Pages 925–931.
Annotation
Измерено поглощение излучения углекислым газом в области 8000 см–1, проведен расчет коэффициентов поглощения с применением асимптотической теории крыльев линий на основе подгонки к экспериментальным данным. Результаты расчета хорошо согласуются с экспериментом. Согласно теории крыльев линий поглощение в крыльях полос обусловлено крыльями сильных линий близлежащей полосы. В рамках этих представлений экспериментальные и расчетные данные о коэффициенте поглощения СО2 в крыльях двух полос в области 8000 см–1 могут являться источником сведений о форме контура спектральных линий при смещенных частотах, отвечающих нескольким десяткам полуширин. Полученные результаты подтверждают гипотезу о том, что параметры контуров в крыльях полос, отвечающих переходам с одним и тем же начальным состоянием, оказываются близкими. Выражение для контура спектральных линий при больших смещенных частотах может быть полезно для расчетов пропускания излучения в окнах прозрачности атмосфер, содержащих СО2.
Klimeshina T.E., Petrova T.M., Rodimova O.B., Solodov A.A., Solodov A.M.,
The СО2 absorption near band heads in the 8000 см -1 region,
Оптика атмосферы и океана, 2013, Volume 26, Issue 11, Pages 925-31.
Annotation
The CO2 absorption is measured in the 8000 cm–1 region, calculation of the absorption coefficient is performed using the asymptotic line wing shape theory with fitting to the experimental data. Calculated coefficient values agree well with the measured data. According to the line wing theory the absorption in the band wings is conditioned by the wings of the strong lines of the near band. Within the framework of the theory, experimental and calculated data on the CO2 absorption coefficient in the wings of two bands in the 8000 cm–1 region can provide the information about the line shape at frequency detunings corresponding to several tens of half-widths. The results obtained support the hypothesis that line shape parameters in the line wings related to the transitions with the same initial state appear to be close to each other. The expression of the spectral line shape at large frequency detunings may be useful for modeling the radiative transfer in the atmospheric windows of the planets with significant CO2 content.
T. E. Klimeshina, T. M. Petrova, O. B. Rodimova, A. A. Solodov, A. M. Solodov,
CO2 absorption in band wings in near IR,
Atmospheric and Oceanic Optics, 2015, Volume 28, Issue 5, Pages 387–393,
DOI: 10.1134/S1024856015050073, https://doi.org/10.1134/S1024856015050073.
Annotation
The CO2 absorption was measured in the 7000 and 8000 cm–1 regions. The absorption coefficients were calculated using the asymptotic line wing shape theory. Line shape parameters were found from fitting to experimental data. The calculation results agree well with the measurement data. According to the line wing theory, the absorption in the band wings is caused by the wings of strong lines of an adjacent band. Within these assumptions, experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7000 and 8000 cm–1 regions can provide information on the line shape at frequency detuning from several tens to several hundreds of half-widths. The results support the hypothesis that line shape parameters in the line wings related to transitions with the same initial state are close to each other. Deviations from a Lorentzian profile are found for some CO2 bands and turn out different for the wings of different bands
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
H. Tran, C. Boulet, S. Stefani, M. Snels, G. Piccioni,
Measurements and modelling of high pressure pure CO2 spectra from 750 to 8500 cm-1. I—central and wing regions of the allowed vibrational bands,
Journal of Quantitative Spectroscopy and Radiative Transfer, 2011, Volume 112, Issue 6, Pages 925-936,
DOI: 10.1016/j.jqsrt.2010.11.021.
Annotation
Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
2
-rich atmospheres like those of Venus and Mars. Despite various measurements and theoretical models dedicated to this subject, accurate data at different temperatures and pressures are still lacking in numerous spectral regions. In this work, using two Fourier Transform Spectrometers, we have measured spectra of pure CO
2
in a large spectral region range, from 750 to 8500 cm
−1
at various densities (3–57 amagat) and temperatures (230–473 K). Comparisons between measured dipolar absorption bands and spectra calculated with the widely used Lorentz line shape show very large discrepancies. This result is expected since the Lorentz approach neglects line-coupling effects due to intermolecular collisions which transfer absorption from the wings to the band center. In order to account for this effect, a theoretical approach based on the impact and Energy Corrected Sudden approximations has been developed. Comparisons of this model with numerous laboratory spectra in a wide range of pressure, temperature and spectral domain show satisfactory agreements for band centers and near wing regions where the impact approximation is valid. However, as expected, due to the breakdown of the impact approximation, the model fails when considering far wing regions. In the absence of precise models accounting for line-mixing
and
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
Pollack J.B., Dalton J.B., Grinspoon D., Wattson R.B., Freedman R., Crisp D., Allen D.A., Bezard B., deBergh C., Giver L.P., Ma Q., Tipping R.H.,
Near-infrared light from Venus’ nightside: a spectroscopic analysis,
Icarus, 1993, Volume 103, Pages 1-42,
DOI: 10.1006/icar.1993.1055.
Annotation
We have simulated near-infrared spectra of the emission from Venus' nightside with a radiative transfer program that allows for emission, absorption, and scattering by atmospheric gases and particles. Except for an O2 airglow emission band near 1.27 µm, the emission is produced in the hot, lower atmosphere of Venus. Its intensity at the top of the atmosphere is substantially decreased by scattering and absorption within the main clouds and is concentrated within spectral "window" regions where the lower atmosphere is most transparent. The twin goals of this paper are to assess the adequacy of current gas databases for simulating Venus' nightside near-IR spectra and, within these limitations, to derive information on gas abundances below the main clouds and the optical thickness of the main clouds. We used the moderate resolution spectra of Crisp et al. (1991) for both these objectives and the very high resolution spectra of Bezard et al. (1990) for the first.
The HITRAN database for the permitted transitions of CO2 is found to be totally inadequate for simulating the near-infrared emission from Venus' nightside. However, much improved simulations can be made when Wattson's high-temperature ("high-T") database of CO2 is used instead. A major weakness of the current gas databases is the lack of accurate information on CO2 and H2O continuum opacity.
Even bright spots on the nightside have substantial cloud-scattering optical depths. We derive cloud optical depths of about 25 at a reference wavelength of 0.63 µm by fitting spectra of three different spots. We find that the H2O mixing ratio has a constant value of 30±10 ppm in the altitude range from 10 to 40 km. We also infer mixing ratios for SO2 of 180±70 ppm at 42 km, HCl of 0.48±0.12 ppm at 23.5 km, HF of 1-5 ppb at 33.5 km, and upper limits on the mixing ratio of CH4 of 0.1 ppm at 30 km and 2 ppm at 24 km.
We show that that it is possible to infer both the mixing ratios of some gas species and their vertical gradients at the centroid of emission in a given spectral window. In particular, we find that OCS has a mixing ratio, α, of 4.4±1.0 ppm and a gradient, dα/dz, of -1.58±0.30 ppm/km at an altitude of 33 km; i.e., the OCS mixing ratio strongly increases with decreaseing altitude. In addition, we find that the corresponding values for CO are 23±5 ppm and +1.20±0.45 ppm/km at an altitude of 36 km. Therefore, within a factor of 2 CO is decreasing toward the surface at the same rate as that as which OCS is increasing. These results are in good agreement with theories of lithospheric buffering and gas thermodynamic equilibrium at the surface that predict a substantial abundance of OCS (several 10s of ppm) at the surface due to reactions in which CO is one of the reactants.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.
X. Huang, D. W. Schwenke, S. A. Tashkun, and T. J. Lee,
An isotopic-independent highly accurate potential energy surface for CO2 isotopologues and an initial 12C16O2 infrared line list,
Journal of Chemical Physics, 2012, Volume 136, Article 124311,
DOI: 10.1063/1.3697540, http://dx.doi.org/10.1063/1.3697540.
Annotation
An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO2 by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spectroscopic accuracy of the Ames-1 PES. It is shown that Ames-1 yields σrms (root-mean-squares error) = 0.0156 cm−1 for 6873 J = 0–117 12C16O2 experimental energy levels, even though less than 500 12C16O2 energy levels were included in the refinement procedure. It is also demonstrated that, without any additional refinement, Ames-1 yields very good agreement for isotopologues. Specifically, for the 12C16O2 and 13C16O2 isotopologues, spectroscopic constants Gv computed from Ames-1 are within ±0.01 and 0.02 cm−1 of reliable experimentally derived values, while for the 16O12C18O, 16O12C17O, 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2, 13C17O2, 17O13C18O, and 14C16O2 isotopologues, the differences are between ±0.10 and 0.15 cm−1. To our knowledge, this is the first time a polyatomic PES has been refined using such high J values, and this has led to new challenges in the refinement procedure. An initial high quality, purely ab initiodipole moment surface (DMS) is constructed and used to generate a 296 K line list. For most bands, experimental IR intensities are well reproduced for 12C16O2 using Ames-1 and the DMS. For more than 80% of the bands, the experimental intensities are reproduced with σrms(ΔI) < 20% or σrms(ΔI/δobs) < 5. A few exceptions are analyzed and discussed. Directions for future improvements are discussed, though it is concluded that the current Ames-1 and the DMS should be useful in analyzing and assigning high-resolution laboratory or astronomical spectra.