We present the first results for resolving methane (CH4) line transition frequencies down to the kilohertz level for overlapping lines using comb-linked cavity ring-down spectroscopy, while most available laboratory measurements, having resolution at the megahertz level, cannot separate merged lines. To demonstrate the technique, Lamb-dip spectra and linear-absorption spectra were used to identify overlapped lines of vibration-rotation spectra in the R9 multiplet of the 2v3 band. Three new weak lines were found for the first time. The experimental methods are extensible to other important bands of CH4 and many other gas-phase molecules, and should provide a more detailed understanding of molecular structure and line parameters for future high-precision studies.

Semantic Web services (SWS) have been hailed for their role in realizing the potential of composing services in the context of service-oriented computing. However, many application domains, such as astrophysics, require a major rethinking of how service composition should take place despite his potential. In this paper, we describe an approach for automatic, user-friendly SWS composition for the astrophysics domain that features certain particularities like correlated or optional inputs, aggregates, and inclusion of non-Web services. The approach selects the best SWSs using non-functional requirements along with users’ previous experience feedback and is demonstrated using some real astrophysics services.

The high resolution infrared spectra of dideuterated hydrogen sulfide D₂S were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer (Zürich prototype ZP2001) and analyzed in the ν₂ fundamental band region, 750–1200 cm^-1. The 1742 transitions (which is more than two times more than in the preceding analogous studies) were assigned in the experimental spectra to the ν2 band (the maximum values of the quantum numbers are  J^max=30 and K^max_a=21). The subsequent weighted fit of experimentally assigned transitions was made with the Watson Hamiltonian, resulting in a set of 34 parameters which reproduces the initial 535 infrared ro–vibrational energy values from 1742 experimental line positions with a root mean square deviation d_rms=1.31*10^-4 cm^-1. An analysis of 280 experimental ro–vibrational line intensities (324 transitions) of the ν₂ band was made using the Hartmann–Tran profile of individual lines, and the results were applied then in the fit of parameters of the effective dipole moment operator. Isotopic relations for the dipole moment parameters were derived and used for the fit procedure. The obtained “model dependent” parameters reproduce the initial line strengths with the d_rms=2.5%. A list of 1742 experimental transitions of D₂S is generated together with the presentation of their individual line strengths calculated on the basis of the obtained effective dipole moment parameters.

Linestrengths, self-broadening and narrowing coefficients for 8 absorption transitions of CO₂ near 1.43 µm were measured using the wavelength modulation direct absorption spectroscopy (WM-DAS) at 300–1000 K and 5–20 kPa. The SNR was enhanced to 1500 for the peak absorbance around 5% at room temperature and remains at 550 for the peak absorbance around 1% at high temperatures by use of the WM-DAS method. The Voigt, Rautian, Galatry and quadratic speed-dependent Voigt profiles were used to recover the absorbance and retrieve the best-fit spectroscopic parameters and their temperature dependence. The quadratic speed-dependent Voigt profile was found to give the best combination of accuracy and robust lineshape parameters. The measured linestrengths and self-broadening coefficients compare well with the available values listed in the HITRAN/HITEMP database. The self-narrowing coefficients were also determined for GP, RP and qSDVP with analyses of the uncertainties in these spectroscopic parameters.

The positions and intensities of 1936 lines observed in the range 7400– of two absorption spectra of ammonia recorded at high resolution using Fourier transform spectroscopy are reported. The accuracy of these line positions is estimated to range from 0.001 to from the lower to the upper limits of the spectral range considered, while the accuracy of the line intensities is estimated to be around 10% or better. Also reported are less-accurately measured positions and intensities of 1985 lines retrieved from these two spectra or from only one of them. These results are compared with the data measured recently in a spectrum recorded in 1980 at the Kitt Peak National Solar Observatory [Barton et al., J. Mol. Spectrosc. 325, 7 (2016)] and provided in HITRAN 2016, as well as line positions and intensities measured in this work in the same Kitt Peak spectrum.

The high resolution infrared spectra of SiD4 were recorded with Bruker IFS120 and IFS125 HR Fourier transform infrared spectrometers at an optical resolution of 0.002 and 0.0021 cm⁻¹ and analyzed in the region of 1480–1700 cm⁻¹ where the stretching bands ν₃ and ν₁ are located. The 2676 transitions with J_max. = 44 were assigned to the ν₃ band.The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes the resonance interactions between the (0010) and (1000) vibrational states into account. As the result, a set of 18 fitted parameters was obtained which reproduces the initial 2676 ro–vibrational transitions with the drms=3.71×10⁻⁴ cm⁻¹.

The strengths of 619 experimentally recorded spectral lines (J^max = 24) of the ν₄ and ν₂ bands of ²⁸SiD₄ were determined from the fit of their line shapes with a Hartmann–Tran line profile and were used then in the weighted fit for determination of the effective dipole moment parameters of these bands. The obtained set of four parameters reproduce the initial experimental line intensities with the d_rms=5.61%. A list of transitions with their line intensities is generated up to the value of quantum number J=37. The half–widths analysis was made on the basis of the multi–spectrum fit with the Hartmann-Tran line profile, and self–pressure broadening coefficients were estimated for 60 lines of the dyad.

Представлен подход, использованный при разработке и реализации модуля, выполняющего бинарные операции над данными в ИС «Молекулярная спектроскопия». Приводится формализация бинарных операций над наборами спектроскопических данных с учетом особенностей предметной области. Описываются алгоритм действий и интерфейс пользователя для проведения бинарных операций – единые для имеющихся баз данных по различным веществам и нескольким типам спектроскопических данных.

New methods of integrating scientific data on the properties of substances and materials that apply modern information technologies are analysed. The capabilities of systems created using the Semantic Web and Big Data are explored. Despite some differences in the tasks that are solved, both approaches are oriented towards working with large arrays of web-distributed, structurally heterogeneous data. Several data-integration platforms that have been developed in recent years, including a system designed by the authors, are studied. It is concluded that currently none of the integration systems can fully satisfy specific the requirements of scientific data. Nevertheless, several software elements and technological solutions are of interest and can support the implementation of a project to integrate scientific data on properties of substances and materials.

(Original Russian Text A.O. Erkimbaev, V.Yu. Zitserman, G.A. Kobzev, A.V. Kosinov, 2018, published in Nauchno-Tekhnicheskaya Informatsiya, Seriya 2: Informatsionnye Protsessy i Sistemy, 2018, No. 10, pp. 11–19. INFORMATION ANALYSIS)

We report the results of ab initio investigation of the S and O branches of the hydrogen molecule perturbed by helium atom. The calculations, based on close-coupling scheme, were performed for vibrational bands from v = 0 to v = 5, and rotational levels up to j = 5. We provide the pressure broadening and shifting coefficients and the real and imaginary parts of Dicke contribution to the Hess profile. The results are important for astrophysical studies, for example as a reference data for studying the gas giants’ atmospheres.

We show in this paper that requantized classical molecular dynamics simulations (rCMDSs) are capable of predicting various refined spectral-shape parameters of absorption lines of CO₂ broadened by N₂ with high precision. Combining CMDSs and a requantization procedure, we computed the auto-correlation function of the CO₂ dipole moment responsible for the absorption transition. Its Fourier-Laplace transform directly yields the spectrum. Calculations were made for two temperatures, 200 and 296 K, at 1 atm and for a large range of Doppler widths, from the near-Doppler to the collision-dominant regimes. For each temperature and each line, the spectra calculated for various Doppler widths were simultaneously fit with the Hartmann-Tran (HT) profile. This refined profile, which takes into account the effects of the speed dependent collisional line broadening, the Dicke narrowing, and the collisional line mixing, was recommended as a reference model to be used in high-resolution spectroscopy (instead of the simplified Voigt model). The HT parameters retrieved from the rCMDS-calculated spectra were then directly compared with those deduced from high-precision measurements [J. S. Wilzewski et al., J. Quant. Spectrosc. Radiat. Transfer 206, 296–305 (2018)]. The results show a very good agreement, even for those parameters whose influence on the spectra is very small. Good agreement is also obtained between measured and predicted temperature dependences of these parameters. This demonstrates that rCMDS is an excellent tool, highly competitive with respect to high quality measurements for precise line-shape studies.

A new line list for AlH is produced. The WYLLoT line list spans two electronic states X¹Σ⁺ and A¹Π⁠. A diabatic model is used to model the shallow potential energy curve of the A¹Π state, which has a strong pre-dissociative character with only two bound vibrational states. Both potential energy curves are empirical and were obtained by fitting to experimentally derived energies of the X¹Σ⁺ and A¹Π electronic states using the diatomic nuclear motion codes dpotfit and duo. High-temperature line lists plus partition functions and lifetimes for three isotopologues ²⁷AlH, ²⁷AlD, and ²⁶AlH were generated using ab initio dipole moments. The line lists cover both the X–X and A–X systems and are made available in electronic form at the cds and exomol data bases.

The performances of a multi-spectral fit for the spectra of pressure-broadened overlapping lines (R₉F₁, R₉F₂) of ¹²CH₄ in binary mixtures with N₂ were studied by applying different lineshape models, from the simplest Voigt profile (VP) to the Harmann-Tran profile (HTP). Line-mixing was approximated in the first order in the spectral fits. Data were acquired using a high-resolution cavity ring-down spectrometer of minimum detectable absorption coefficient of 2.8 × 10⁻¹² cm⁻¹. The lines were observed with a signal-to-noise ratio of 19 365 for pressures from 5 to 40 kPa. The study reveals that the multi-spectral fits using the HTP and the speed-dependent Nelkin–Ghatak profile (SDNGP) yield the best among all tested. The two models gave the maximum relative residuals of less than 0.065 %. All things considered, the HTP and the SDNGP appear to be the most reliable models for treating the present case of multi-spectral fitting of unresolved dual-component spectra.

In this work, we report calculated vibrational energy levels of the methane molecule up to 10 300 cm⁻¹. Two potential energy surfaces constructed in quite different coordinate systems with different analytical representations are employed in order to evaluate the uncertainty of vibrational predictions. To calculate methane energy levels, we used two independent techniques of the variational method. One method uses an exact kinetic energy operator in internal curvilinear coordinates. Another one uses an expansion of Eckart-Watson nuclear motion Hamiltonian in rectilinear normal coordinates. In the Icosad range (up to five vibrational quanta bands–below 7800 cm⁻¹), the RMS standard deviations between calculated and observed energy levels were 0.22 cm⁻¹ and 0.41 cm⁻¹ for these two quite different approaches. For experimentally well-known 3v₃ sub-levels, the calculation accuracy is estimated to be ∼1 cm⁻¹. In the Triacontad range (7660-9188 cm⁻¹), the average error of the calculation is about 0.5 cm⁻¹. The accuracy and convergence issues for higher energy ranges are discussed.

The dependence of the intermolecular interaction potentials on the vibrational quantum numbers of the H₂O molecule is derived for the H₂O–Ne, H₂O–Kr, and H₂O–Xe systems. The broadening γ and shift δ coefficients are calculated for seven vibrational bands ν₁, ν₂, ν₃, 2ν₂, ν₁ + ν₂, ν₂ + ν₃, and ν₁ + ν₂ + ν₃ of the H₂O molecule from the absorption region 640–9550 cm⁻¹. An analytical formula is suggested for calculation of the broadening coefficients γ at T = 296 K. It is shown that the excitation of stretching modes of the vibrations in the H₂O molecule increases the broadening coefficients. The influence of the bending vibrations on γ is insignificant.

Thirty well isolated ro-vibrational transitions of the 30011e – 00001e band of ¹²C¹⁶O₂ at 1.54 μm have been recorded with a laser-locked cavity ring-down spectrometer. The line intensities were obtained with accuracies better than 0.85%. Comparisons of the line intensities determined in this work with literature experimental values and those from HITRAN2016, AMES, UCL-IAO and CDSD-296 line lists are given.

The very weak absorption spectrum of natural CO₂ near 1.74 µm (5702–5879 cm⁻¹) is studied at high sensitivity. The investigated region corresponds to a transparency window of very weak opacity which is of particular interest for Venus. Very weak lines with intensity value as low as 10⁻³⁰ cm/molecule at 296 K are detected by Cavity Ring Down Spectroscopy. On the basis of the predictions of effective Hamiltonian models, 1135 lines of six carbon dioxide isotopologues - ¹²C¹⁶O₂, ¹³C¹⁶O₂, ¹⁶O¹²C¹⁸O, ¹⁶O¹²C¹⁷O, ¹⁶O¹³C¹⁸O and ¹⁶O¹³C¹⁷O - were rovibrationnally assigned to 26 bands. The accurate spectroscopic parameters of 16 bands are determined from standard band-by-band analysis (typical rms deviations of the line positions are 8 × 10⁻⁴ cm⁻¹).

These newly observed bands include perturbed bands, weak hot bands and bands of minor isotopologues (in particular ¹⁶O¹²C¹⁸O in natural abundance) and provide critical validation tests for the most recent spectroscopic databases. The comparison to the Carbon Dioxide Spectroscopic Databank (CDSD), HITRAN2016 database and recent ab initio line lists is presented. Deficiencies are evidenced for some weak perpendicular bands of the HITRAN2016 list and identified as due to inaccurate CDSD intensities which were preferred to ab initio intensities. While Ames and UCL ab initio intensities are believed to be accurate within a few % for the strong unperturbed bands, the reported measurements allow testing important (>50%) differences between ab initio values of some weak perturbed bands.

A set of high-resolution absorption spectrometers based on TDLAS was used to determine the impact of combustion-relevant gases on the pressure shift and broadening of H2O, CO2, C2H2 and CH4 absorption lines in the near-infrared spectral region. In particular, self- and foreign-broadening coefficients induced by CO2, N2, O2, air, C2H2 and CH4 were measured. The absorption lines under investigation are suitable to measure the respective species in typical combustion environments via laser absorption spectroscopy. Additionally, species-dependent self- and foreign-induced pressure shift coefficients were measured and compared to the literature. The experiments were performed in two specifically designed absorption cells over a wide pressure range from 5 to 180 kPa. Different sources of uncertainty were identified and quantified to achieve relative measurement uncertainties of 0.7–1.5% for broadening coefficients and 0.6–1.6% for pressure shift coefficients.

Both ontology builders and users need a way to evaluate ontologies in terms of usability, but existing ontology evaluation approaches do not fit this purpose. We propose the Ontology Usability Scale (OUS), a ten-item Likert scale derived from statements prepared according to a semiotic framework and an online poll in the Semantic Web community to provide a practical way of ontology usability evaluation. Case studies were conducted to bookkeep current usability evaluation results for ontologies expecting revisions in the future, and discussions of the poll results are presented to help proper use and customization of the OUS.

The infrared spectrum of ammonia has proven to be highly problematic for effective Hamiltonian analysis. The most complete previous study of the 3ν₂ and ν₄+ν₂ bands achieved the accuracy of 0.0069 cm⁻¹ as reflected by the root-mean-square error of their fit, which is slightly more than 10 times the experimental accuracy. In the present study, we performed a global fit of the existing 2141 literature data involving 3ν₂, ν₄+ν₂, 3ν₂-ν₂, (ν₄+ν₂)-ν₂ together with 1281 new data involving 3ν₂-2ν₂, 3ν₂-3ν₂ and (ν₄+ν₂)-(ν₄+ν₂) using an effective Hamiltonian together with the Pickett suite of program SPFIT/SPCAT. The new dataset consists of three spectra recorded at the SOLEIL synchrotron facility. The effective Hamiltonian model proposed for 3ν₂/ν₄+ν₂ has achieved experimental accuracy. This success combined with our previous success of the 2ν₂/ν₄ analysis leads us to believe that the vibrational states higher than 3ν₂/ν₂+ν₄ may be analyzed with effective Hamiltonians as well.

Positions and intensities for transitions in the 1←0 bands of the four CO isotopologues (¹²C¹⁶O, ¹³C¹⁶O, ¹²C¹⁸O and ¹³C¹⁸O) were retrieved from analyses of spectra of different low-pressure pure samples and high-pressure air-broadened mixtures (1940–2260 cm⁻¹) in two different multispectrum fittings involving selected groups of 21 (for ¹³C¹⁶O) and 20 (for ¹²C¹⁸O) spectra. Air-broadened half-width and air-shift coefficients, their temperature dependences, line mixing via off-diagonal relaxation matrix element coefficients for CO-air collision systems, and quadratic speed dependence parameters were measured for ¹³C¹⁶O and ¹²C¹⁸O transitions. In both the fittings, two low-pressure room-temperature spectra of a high purity natural sample of CO recorded with the Kitt Peak FTS were included to retrieve the positions and intensities of ¹²C¹⁶O transitions. All other spectra in the fittings were obtained with either ¹³C-enriched or ¹⁸O-enriched samples using the JPL Bruker IFS-125HR FTS. Four absorption cells with path lengths between 0.5131(5) and 20.38(2) cm were used to record the data. The cells are temperature controlled, except for the shortest cell. Positions and intensities for the 1←0 band transitions were determined from the retrieved ro-vibrational constants (G, B, D and H), band intensity and Herman-Wallis parameters by applying the theoretical quantum mechanical expressions. The band strengths of ¹²C¹⁶O, ¹²C¹⁸O and ¹³C¹⁸O are very close (∼0.3%) to HITRAN2012 values but for ¹³C¹⁶O the band strength is ∼4.8% larger than the HITRAN2012 and 2.6% larger than the HITRAN2016 value.

The collision-induced broadening (2γ_OH-A) and shift (δ_OH-A) parameters of hydroxyl radical (OH) with two collisional partners - argon and nitrogen - and their associated temperature-dependence coefficients (n_A and m_A, respectively), have been measured in a series of shock tube experiments. The Q₁(5) OH transition, a member of the A²Σ – X²Π (0, 0) rovibronic band with a line-center wavelength near 308.6 nm, represents an ideal target for quantitative spectroscopy in combustion applications, owing to its strength and degree of relative spectral isolation. Narrow-width tunable UV light was used to sample the Q₁(5) lineshape profile across 8–10 wavelengths. The data were subsequently fit to the Voigt lineshape model at the fixed temperature, pressure and mixture composition. Measurements are presented for 2γ_OH-Ar, δ_OH-Ar, n_Ar, and m_Ar, recommended for T = 1300–2000 K, as well as 2γ_OH-N2, δ_OH-N2, n_N2, and m_N2, recommended for T = 1600–2000 K. The Q₁(5) lineshape was also measured at pressures of 45 and 95 atm, for which application of the Voigt model yielded values of 2γ_OH-Ar and δ_OH-Ar that were consistent with lower-pressure measurements, supporting the validity of the lineshape model and, particularly, the diagnostic in question at such pressures.

In this work, we measured the absorption by CO₂+H₂O mixtures from 2400 to 2600 cm⁻¹ which corresponds to the spectral region beyond the ν3 band head of CO₂. Transmission spectra of CO2 mixed with water vapor were recorded with a high-resolution Fourier-transform spectrometer for various pressure, temperature and concentration conditions. The continuum absorption by CO₂ due to the presence of water vapor was determined by subtracting from measured spectra the contribution of local lines of both species, that of the continuum of pure CO₂ as well as of the self- and CO₂-continua of water vapor induced by the H₂O-H₂O and H₂O-CO₂ interactions. The obtained results are in very good agreement with the unique previous measurement (in a narrower spectral range). They confirm that the H₂O-continuum of CO₂ is significantly larger than that observed for pure CO₂. This continuum thus must be taken into account in radiative transfer calculations for media involving CO₂ + H₂O mixture. An empirical model, using sub-Lorentzian line shapes based on some temperature-dependent correction factors χ is proposed which enables an accurate description of the experimental results.

The absorption spectrum of water vapor enriched in oxygen-17 has been recorded by a continuous-wave cavity ring-down spectrometer (CW-CRDS) at room temperature in the 12,277–12,894 cm⁻¹ region. The typical sensitivity of 2 × 10−10 cm⁻¹ allowed the detection of water vapor transitions with intensities larger than 1 × 10 ⁻²⁸ cm⁻¹ /(molecule cm⁻²). In total, more than 3400 lines were observed in the recorded spectra with a typical frequency accuracy of 0.002 cm⁻¹. In which more than 3400 transitions were ro-vibrationally assigned to five water isotopic species (H₂¹⁷O, H₂¹⁶O, H₂¹⁸O, HD¹⁶O, and HD¹⁷O) using the known empirical energy levels combined with the calculated variational line lists based on the results of Partridge and Schwenke. About 1300 transitions of H₂¹⁷O were assigned, leading to the determination of new energy levels of 17 vibration states. Those assigned H217 O transitions are involved with the upper vibration states of (013), (023), (032), (051), (061), (070), (080), (090), (112), (131), (150), (160), (211), (230), (301), (310), and (320). The maximum values of the rotational numbers J and Ka were 16 and 9, respectively. The 5ν1 band of HD¹⁷O was assigned for the first time as well. The line positions and energy levels determined in this work were compared with literature, and it shows a significant improvement of the line positions of H₂ ¹⁷O and HD¹⁷O in the 12,277–12,894 cm⁻¹ region.

Room temperature NH3 absorption spectra recorded at the Kitt Peak National Solar Observatory in 1980 are analyzed. The spectra cover two regions in the visible: 15,200 – 15,700 cm^-1 and 17,950 – 18,250 cm^-1. These high overtone rotation-vibration spectra are analyzed using both combination differences and variational line lists. Two variational line lists were computed using the TROVE nuclear motion program: one is based on an ab initio potential energy surface (PES) while the other used a semi-empirical PES. Ab initio dipole moment surfaces are used in both cases. 95 energy levels with J=1-7 are determined from analysis of the experimental spectrum in the 5νNH (red) region and 46 for 6νNH (green) region. These levels span four vibrational bands in each of the two regions, associated with stretching overtones.

The spectra of the Н₂¹⁶О and Н₂¹⁸О vapor have been recorded between 16,460 and 17,200 cm⁻¹ by a Fourier transform spectrometer with spectral resolution of 0.05 cm⁻¹ using high luminance LED light source and 60 cm multipath cell with a path length of 3480 cm. A high signal-to-noise ratio (S/N ≈ 5000) enable us to register the lines with intensities of 1.54 × 10⁻²⁴ to 2.0 × 10⁻²⁷ cm/molecule. More than 1300 lines were recorded in the spectrum of the natural abundance water vapor and over 1800 lines in the spectrum of the vapor enriched by ¹⁸O. 422 rotation-vibration energy levels of the H₂¹⁸O molecule have been assigned to twenty vibrational states. The majority of these energies was attributed to the (241), (321), (340), (420), (401), (500), and (123) states. 43 energy levels were tentatively assigned to the (043), (142), (302), (161), (260), and (062) states. Eleven energy levels were labeled as belonging to the (280), (081), (190), (0 10 0), (1 10 0), (0 11 0), and (0 12 0) states. The recorded spectra were compared with the simulations based on the HITRAN2016 database and variational lists.

N₂ pressure broadening and shifting coefficients are presented for about 300 strongest water vapor lines in the 16,600–17,060 cm⁻¹ spectral region. The spectra have been recorded with a spectral resolution of 0.05 cm⁻¹ at room temperature by a Fourier transform spectrometer using a high luminance LED light source. A high signal-to-noise ratio (S/N ≈ 10 000) permits the analyses of the lines with intensities from 1.54 × 10⁻²³ to 2.0 × 10⁻²⁶ cm/molecule. The multi-spectrum fitting procedure was used to fit line parameters of the ν₁+ 4ν₂+ 2ν₃, 3ν₁+ 2ν₂+ ν₃, 4ν₁+ ν₃, 4ν₁+ 2ν₂, 5ν₁ bands for the temperature T = 297 K. Line broadening and shifting calculations are performed using a semi-empirical method, which is based on the impact theory of broadening, and includes the correction factors whose parameters were determined by fitting the broadening coefficients of 12 lines to the experimental data. The method was further developed for the estimate of line profiles using the an harmonic wave functions.

A new study of ¹²CH₄ line positions and intensities was performed for the Tetradecad regions 5550,000–5695.250, 5718.8–5724.250 and 5792.36–5814.290 cm⁻¹ using long path (202 m, 602 m, 1604 m and 1804 m) spectra of normal samples of CH₄ at different pressures recorded with a Fourier transform spectrometer in Reims, France. Line positions and intensities were retrieved by least squares curve-fitting procedures and analyzed using the effective Hamiltonian and the effective dipole moment expressed in terms of irreducible tensor operators adapted to spherical top molecules. An 80 K spectrum recorded in Jet Propulsion Laboratory (JPL), Pasadena, of enriched ¹²CH₄ was used for low-J line positions. Another 80 K spectrum of enriched ¹³CH₄ from JPL was used to discern the isotopic lines. A new measured linelist contains positions and intensities for 5819 features. Quantum assignments were made for more than 3400 transitions, which represent ∼95% of the integrated line intensity observed in this region. All assigned 3445 line positions were fitted with RMS standard deviations of 0.0024 cm⁻¹. The sum of observed intensities between 5550 and 5695 cm⁻¹ fell within 2% of the predicted value from ab initio variational calculations reported in the TheoReTS database (http://theorets.univ-reims.fr; http://theorets.tsu.ru).

Variationally computed infrared spectra in the range [0-5000] cm^-1 are reported for the deuterated PH₂D and PHD₂ molecules from accurate potential energy and dipole moment surfaces initially derived for the major isotopologue PH₃(C_3v ). Energy level and line intensity calculations were performed by using a normal-mode model combined with isotopic and symmetry transformations for the H → D substitutions. Theoretical spectra were computed at 296 K up to J_max = 30 and will be made available through the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru). For the very first time, ab initio intensity predictions of PH₂D/PHD₂ are in good qualitative agreement with the literature. This work will be useful for spectral intensity analysis for which accurate spectral intensity data are still missing.

The emission spectrum of the 0-0; 1-1 and 2-2 bands of the C²Σ⁺ -  X²Π system in the CD molecule have been obtained using a stainless steel hollow-cathode lamp with two anodes and filled with a mixture of He buffer gas and CD₄. The emission from the discharge was observed with high accuracy dispersive optical spectroscopy using a plane-grating spectrograph and recorded by a photomultiplier tube. In total, 428 transition frequencies belonging to the three bands were precisely measured and rotationally analyzed. The current data were elaborated with the help of precise ro-vibrational and equilibrium ground state parameters reported by Zachwieja et al. (2012) from investigation of the A²Δ - X²Π transition. The spin-rotation interaction constants γ_v and γ_D;v of the C²Σ⁺ v = 0,1,2 levels were obtained for the first time. Moreover, the main equilibrium parameters of the third excited state were obtained as follows: T_e = 31,825.944ð12 cm^-1, ω_e = 2078.803(27) cm^-1, ω_ex_e = 59.558(12) cm^-1, B_e = 7:86810ð23 cm^-1, α_e = 0.25315ð58 cm^-1 and γ_e = 0.01518ð28 cm^-1.

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.

The high-resolution FTIR spectrum of the 2v₂ band (3250–3380 cm⁻¹) of D₂¹³CO was recorded at an unapodized resolution of 0.0063 cm⁻¹. A total of 747 rovibrational transitions have been assigned and fitted up to J″ = 32 and K_a″ = 10 using the Watson’s A-reduced Hamiltonian in the I^r representation. A set of accurate upper state (v₂= 2) rovibrational constants, three rotational and five quartic centrifugal distortion constants, were determined for the first time. The band center of the 2v₂ band was found to be 3326.765109 ± 0.000079 cm⁻¹. The rms deviation of the rovibrational fit was 0.00096 cm⁻¹.

The consistency of all data that have been published to date on the rovibrational line centers of the hydrogen chloride molecule HCl is analyzed. It was revealed that a number of corrections are needed because of systematic inaccuracies in the line center determination. A simultaneous fit of rovibrational transition frequencies was performed in the region from 7.4 to 18075 cm^–1. The isotopically independent spectroscopic parameters for calculating rovibrational energy levels in the ground electronic state are determined. The calculated line centers are compared with the HITRAN data. The obtained spectroscopic parameters are used to calculate the turning points (rmin and rmax) of RKR-potentials of HCl isotopologues. The use of experimental data, including the highest vibrational state with V_max = 8 that lies approximately at half the potential well depth allowed the pointwise potentials to be calculated up to Vmax = 20.

The FAIR guiding principles for research data stewardship (findability, accessibility, interoperability, and reusability) look set to become a cornerstone of research in the life sciences. A critical appraisal of these principles in light of ongoing discussions and developments about data sharing is in order. The FAIR principles point the way forward for facilitating data sharing more systematically — provided that a number of ethical, methodological, and organisational challenges are addressed as well.

The non-relativistic variational calculation of a complete set of ro-vibrational states in the H⁺₂ molecular ion supported by the ground 1sσ adiabatic potential is presented. It includes both bound states and resonances located above the n = 1 threshold. In the latter case we also evaluate a predissociation width of a state wherever it is significant. Relativistic and radiative corrections are discussed and effective adiabatic potentials of these corrections are included as supplementary files.

We present an accurate measurement of the weak quadrupole S(2) 2-0 line in self-perturbed D₂ and theoretical ab initio calculations of both collisional line-shape effects and energy of this rovibrational transition. The spectra were collected at the 247–984 Torr pressure range with a frequency-stabilized cavity ring-down spectrometer linked to an optical frequency comb (OFC) referenced to a primary time standard. Our line-shape modeling employed quantum calculations of molecular scattering (the pressure broadening and shift and their speed dependencies were calculated, while the complex frequency of optical velocity-changing collisions was fitted to experimental spectra). The velocity-changing collisions are handled with the hard-sphere collisional kernel. The experimental and theoretical pressure broadening and shift are consistent within 5% and 27%, respectively (the discrepancy for shift is 8% when referred not to the speed averaged value, which is close to zero, but to the range of variability of the speed-dependent shift). We use our high pressure measurement to determine the energy, ν₀, of the S(2) 2-0 transition. The ab initio line-shape calculations allowed us to mitigate the expected collisional systematics reaching the 410 kHz accuracy of ν₀. We report theoretical determination of ν₀ taking into account relativistic and QED corrections up to α⁵. Our estimation of the accuracy of the theoretical ν₀ is 1.3 MHz. We observe 3.4σ discrepancy between experimental and theoretical ν₀.

The technique of frequency-stabilized comb-calibrated cavity ring-down spectroscopy was used to observe the weak R(1) transition of the deuturated molecular hydrogen (HD) first overtone band in the near infrared. Like molecular hydrogen, HD is a benchmark system to test quantum electrodynamics, looking for new physics beyond the standard model. The spectral line shape was measured with an extremely high fidelity at relatively low gas pressures. The use of a very refined line-shape model allowed us to retrieve the unperturbed line-center frequency of the R(1) line with a global uncertainty of about 100 kHz (δν/ν=5×10−10). Our value may solve the ambiguity that recently emerged for this line from a pair of sub-Doppler experiments. We also determined other parameters of interest, such as the line strength, the transition dipole moment, and the pressure-broadening coefficien

The methane absorption spectrum is studied at 297 K and 80 K in the center of the Tetradecad between 5695 and 5850 cm⁻¹. The spectra are recorded by differential absorption spectroscopy (DAS) with a noise equivalent absorption of about α_min≈ 1.5 × 10⁻⁷ cm⁻¹. Two empirical line lists are constructed including about 4000 and 2300 lines at 297 K and 80 K, respectively. Lines due to ¹³CH₄ present in natural abundance were identified by comparison with a spectrum of pure ¹³CH₄ recorded in the same temperature conditions. About 1700 empirical values of the lower state energy level, E_emp, were derived from the ratios of the line intensities at 80 K and 296 K. They provide accurate temperature dependence for most of the absorption in the region (93% and 82% at 80 K and 296 K, respectively). The quality of the derived empirical values is illustrated by the clear propensity of the corresponding lower state rotational quantum number, J_emp, to be close to integer values. Using an effective Hamiltonian model derived from a previously published ab initio potential energy surface, about 2060 lines are rovibrationnally assigned, adding about 1660 new assignments to those provided in the HITRAN database for ¹²CH₄ in the region.

We report measurement results for line positions, intensities, half-width, and pressure-induced shift coefficients and line mixing coefficients for N2O broadened by air in the ν3 band. The high signal-to-noise ratio spectra have been recorded at high resolution using the McMath-Pierce Fourier transform spectrometer formerly located at the National Solar Observatory on Kitt Peak, Ariz., USA. The spectra were analyzed using a multispectrum nonlinear least-squares curve-fitting technique employing the speed-dependent Voigt profile with a Rosenkranz (weak) line mixing component. The speed dependence parameters were calculated as suggested in the study of Kochanov (J. Quant. Spectrosc. Radiat. Transf. 189, 18 (2017). doi:10.1016/j.jqsrt.2016.11.007). Several comparisons have been performed between the retrieved parameters and previously published results. For |m| ≤ 40, our results for line positions, broadening, and line mixing coefficients agree best with the results of Loos et al. (J. Quant. Spectrosc. Radiat. Transf. 151, 300 (2015). doi:10.1016/j.jqsrt.2014.10.008). Also, we compared the obtained line positions and intensities with the corresponding values in HITRAN2016 and GEISA-2015 databases. No significant or systematic differences were noticed. The precision of our line positions was estimated to be 3 × 10⁻⁵ cm⁻¹. The reported line positions, intensities, and air-broadening coefficients are accurate to better than 2%. The accuracy of air-pressure-induced line shifts and line mixing coefficients is better than 5%. The line mixing coefficients and air-broadening coefficients were also calculated using the exponential power gap scaling law, and these calculated values were found to be in good agreement with the experimental results.

Pure CO₂ spectra recorded at room temperature and different pressures (0.2–140 Torr) have been analyzed with the help of a fitting routine that takes into account asymmetries arising in the spectral lines due to pressure induced effects such as line mixing. The fitting procedure used in this study allows one to adjust the ro-vibrational constants for the band rather than fitting for individual line parameters. These constrained parameters greatly reduce the measurement uncertainties and allow us to observe the behavior of the weak lines corresponding to high J quantum numbers. We have also calculated line mixing parameters using approximations based on exponential nature of the energy difference between ground and upper vibrational states involved in the ro-vibrational band transitions. The calculated results show good agreement when compared with the experimentally determined parameters.

(J, K)-line broadening and shift coefficients with their temperature-dependence characteristics are computed for the perpendicular (ΔK = ±1) ν₆ band of the ¹²CH₃D-N₂ system. The computations are based on a semi-empirical approach which consists in the use of analytical Anderson-type expressions multiplied by a few-parameter correction factor to account for various deviations from Anderson's theory approximations. A mathematically convenient form of the correction factor is chosen on the basis of experimental rotational dependencies of line widths, and its parameters are fitted on some experimental line widths at 296 K. To get the unknown CH₃D polarizability in the excited vibrational state v₆ for line-shift calculations, a parametric vibration-state-dependent expression is suggested, with two parameters adjusted on some room-temperature experimental values of line shifts. Having been validated by comparison with available in the literature experimental values for various sub-branches of the band, this approach is used to generate massive data of line-shape parameters for extended ranges of rotational quantum numbers (J up to 70 and K up to 20) typically requested for spectroscopic databases. To obtain the temperature-dependence characteristics of line widths and line shifts, computations are done for various temperatures in the range 200–400 K recommended for HITRAN and least-squares fit procedures are applied. For the case of line widths strong sub-branch dependence with increasing K is observed in the R- and P-branches; for the line shifts such dependence is stated for the Q-branch.

Paper is dedicated to the new approach to distributed industrial systems (IS) sustainability/vulnerability assessment. This approach is based on the unitary multiset grammars (UMG) as a flexible and convenient tool designed specially for large systems analysis and optimization. UMG description of IS technological base as well as multiset representation of order completed by the IS, its resource base and impact on the IS are presented. Criterion for recognition of IS sustainability to the impact is formulated. UMG extension for natural disasters impacts (NDI) representation is introduced, and criterion for recognition of IS sustainability to the NDI is also presented. The solution of the reverse problem, concerning part of the order, which may be completed by the affected IS, is described. Implementation issues are considered.

This paper describes a Virtual Research Environment (VRE) based on a web GIS platform ‘­Climate+’, which provides an access to analytic instruments processing 19 collections of ­meteorological and climate data of several international organizations. This environment ­provides ­ystematization  sof spatial data and related climate information and allows a user getting ­analysis results using geoinformation technologies. The ontology approach to this ­ s ystematization is described, ­making it possible to match semantics of meteorological and climate parameters presented in different collections and used in solving various applied problems.

A low-resolution (0.5 cm⁻¹) Fourier transform infrared (FTIR) spectrum of formaldehyde-d₂ (D₂¹²CO) in the 2500–4500 cm⁻¹ region was recorded to study the combination bands in this region. The bands ν₂+ν₄, ν₂+ν₆, ν₂+ν₃, ν₁+ν₂, ν₂+ν₅, ν₂+ν_{5 ,} 3ν₃, 2ν₂ and 2ν₅ were identified and their band centers (with an uncertainty of ± 0.1 cm⁻¹) and band types were determined. Furthermore, the high-resolution FTIR spectrum of the 2ν₂ overtone band (3315–3440 cm⁻¹) of D₂¹²CO was recorded at an unapodized resolution of 0.0063 cm⁻¹ and its infrared lines were analyzed. A total of 970 rovibrational transitions have been assigned and fitted up to J′ = 35 and K_a′ = 14 using the Watson’s A-reduced Hamiltonian in the I^r representation. Upper state (ν₂= 2) rovibrational constants inclusive of three rotational and five quartic centrifugal distortion constants were accurately determined for the first time. The band center of the 2ν₂ band was determined as 3385.200666 ± 0.000035 cm⁻¹. The rms deviation of the rovibrational fit was 0.00093 cm⁻¹. From the fitting of 451 ground state combination differences (GSCDs) of D₂¹²CO which were derived from the infrared transitions of the 2ν₂ band of this work, together with 360 microwave frequencies from a previous study, new and accurate ground state constants of D₂¹²CO up to three octic terms were obtained. The combination and overtone bands and the newly assigned high-resolution infrared lines of the 2ν₂ band in the 2500–4500 cm⁻¹ region can be used to detect D₂¹²CO in this infrared region. In addition, the results derived from this study give information on the rovibrational molecular structure of D₂¹²CO.

An absorption spectrum of H₂¹⁶O at 1950 K is recorded in a premixed methane/air flat flame using a cavity-enhanced optical frequency comb-based Fourier transform spectrometer. 2417 absorption lines are identified in the 6250–6670 cm^-1 region with an accuracy of about 0.01 cm^-1. Absolute line intensities are retrieved using temperature and concentration values obtained by tunable diode laser absorption spectroscopy. Line assignments are made using a combination of empirically known energy levels and predictions from the new POKAZATEL variational line list. 2030 of the observed lines are assigned to 2937 transitions, once blends are taken into account. 126 new energy levels of H₂¹⁶O are identified. The assigned transitions belong to 136 bands and span rotational states up to J=27.

The water vapour line broadening and shifting for 97 lines in the ν₁ + ν₂ + ν₃ band induced by hydrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm⁻¹ and in a wide pressure range of H₂. The calculations of the broadening γ and shift δ coefficients were performed in the semi-classical method framework with use of an effective vibrationally depended interaction potential. Two potential parameters were optimised to improve the quality of calculations. Good agreements with measured broadening coefficients were achieved. The comparison of calculated broadening coefficients γ with the previous measurements is discussed. The analytical expressions that reproduce these coefficients for rotational, ν₂, ν₁, and ν₃ vibrational bands are presented.

Transition  intensities  for  small  molecules  such  as water and CO₂ can now be computed with such high accuracy  that  they  are  being  used  to  systematically replace  measurements  in  standard  databases.  These calculations use high-accuracy ab initio dipole moment surfaces  and  wave  functions  from  spectroscopically determined  potential  energy  surfaces  (PESs).  Here, an  extra  high-accuracy  PES  of  the  water  molecule (H₂¹⁶O)  is  produced  starting  from  an ab  initio PES which is then refined to empirical rovibrational energy levels.  Variational  nuclear  motion  calculations  using this   PES   reproduce   the   fitted   energy   levels   with a  standard  deviation  of  0.011 cm−1,  approximately three   times   their   stated   uncertainty.   The   use   of wave  functions  computed  with  this  refined  PES  is found to improve the predicted transition intensities for  selected  (problematic)  transitions.  A  new  room temperature  line  list  for  H216O  is  presented.  It  is suggested that the associated set of line intensities is the most accurate available to date for this species.

The remote method of simultaneous determination of the temperature and concentration of hot gases from experimental spectral characteristics is validated on the example of the transmission spectra of water vapor measured with an average error of 5% at temperatures in the range 500–1770 K and concentrations 0.17–1 atm with resolution of 1 cm^–1. When solving the direct optical problem, the parameters of water vapor spectral lines comprised in the HITEMP2010 database are analyzed with allowance for the last measurements of the absorption spectra with high resolution at Т ≈ 1300 K. It is demonstrated that overestimated values of the intensities of some hot water vapor spectral lines can be a reason for the deviation of the theoretical absorption predicted on the basis of the HITEMP2010 database from the experimental one. To increase the accuracy of solving the inverse optical problem, the data from several (up to eight) fragments of the spectral ranges 1000–2500 and 2600–4400 cm^–1 are used. As a result, it is demonstrated that this allows the average error of determining reference values of the water vapor temperature and concentration to be decreased approximately to 0.3%, which corresponds to the average approximation error of theoretical values of its transmission function.

Collision-induced absorption is the phenomenon in which interactions between colliding molecules lead to absorption of light, even for transitions that are forbidden for the isolated molecules. Collision-induced absorption contributes to the atmospheric heat balance and is important for the electronic excitations of O₂ that are used for remote sensing. Here, we present a theoretical study of five vibronic transitions in O₂-O₂ and O₂-N₂, using analytical models and numerical quantum scattering calculations. We unambiguously identify the underlying absorption mechanism, which is shown to depend explicitly on the collision partner-contrary to textbook knowledge. This explains experimentally observed qualitative differences between O₂-O₂ and O₂-N₂ collisions in the overall intensity, line shape and vibrational dependence of the absorption spectrum. It is shown that these results can be used to discriminate between conflicting experimental data and even to identify unphysical results, thus impacting future experimental studies and atmospheric applications.

Quantum mechanical calculations of ro-vibrational energies of CH₄, CHD₃, CH₃D, and CH₃F were made with two different numerical approaches. Both use polyspherical coordinates. The computed energy levels agree, confirming the accuracy of the methods. In the first approach, for all the molecules, the coordinates are defined using three Radau vectors for the CH₃ subsystem and a Jacobi vector between the remaining atom and the centre of mass of CH₃. Euler angles specifying the orientation of a frame attached to CH₃ with respect to a frame attached to the Jacobi vector are used as vibrational coordinates. A direct product potential-optimized discrete variable vibrational basis is used to build a Hamiltonian matrix. Ro-vibrational energies are computed using a re-started Arnoldi eigensolver. In the second approach, the coordinates are the spherical coordinates associated with four Radau vectors or three Radau vectors and a Jacobi vector, and the frame is an Eckart frame. Vibrational basis functions are products of contracted stretch and bend functions, and eigenvalues are computed with the Lanczos algorithm. For CH₄, CHD₃, and CH₃D, we report the first J > 0 energy levels computed on the Wang-Carrington potential energy surface [X.-G. Wang and T. Carrington, J. Chem. Phys. 141(15), 154106 (2014)]. For CH₃F, the potential energy surface of Zhao et al. [J. Chem. Phys. 144, 204302 (2016)] was used. All the results are in good agreement with experimental data.

The ν₃ C–H stretching region of methane was reinvestigated in this work using high temperature (620-1715 K) emission spectra recorded in Rennes at Doppler limited resolution. This work follows our recent global analysis of the Dyad system Δn = ±1 (1000–1500 cm⁻¹), with n being the polyad number [B. Amyay et al., J. Chem. Phys. 144, 24312 (2016)]. Thanks to the high temperature, new assignments of vibration-rotation methane line positions have been achieved successfully in the Pentad system and some associated hot bands (Δn = ±2) observed in the spectral region 2600-3300 cm⁻¹. In particular, rotational assignments in the cold band [Pentad-ground state (GS)] and in the first related hot band (Octad-Dyad) were extended up to J = 30 and 27, respectively. In addition, 1525 new transitions belonging to the Tetradecad-Pentad hot band system were assigned for the first time, up to J = 20. The effective global model used to deal with the new assignments was developed to the 6th order for the first three polyads (Monad, Dyad, and Pentad), and to the 5th order for both the Octad and the Tetradecad. 1306 effective parameters were fitted with a dimensionless standard deviation σ = 2.64. The root mean square deviations dRMS obtained are 4.18 × 10⁻³ cm⁻¹ for the Pentad-GS cold band, 2.48 × 10⁻³ cm⁻¹ for the Octad-Dyad, and 1.43 × 10⁻³ cm⁻¹ for the Tetradecad-Pentad hot bands.

Doppler-free saturated-absorption Lamb dips were measured at sub-Pa pressures on rovibrational lines of H2¹⁶O near 7180 cm⁻¹, using optical feedback frequency stabilized cavity ring-down spectroscopy. The saturation of the considered lines is so high that at the early stage of the ring down, the cavity loss rate remains unaffected by the absorption. By referencing the laser source to an optical frequency comb, transition frequencies are determined down to 100 Hz precision and kHz accuracy. The developed setup allows resolving highly K-type blended doublets separated by about 10 MHz (to be compared to a HWHM Doppler width on the order of 300 MHz). A comparison with the most recent spectroscopic databases is discussed. The determined K-type splittings are found to be very well predicted by the most recent variational calculations.

Molecular hydrogen and its isotopic and ionic species are benchmark systems for testing quantum chemical theory. Advances in molecular energy structure calculations enable the experimental verification of quantum electrodynamics and potentially a determination of the proton charge radius from H2 spectroscopy. We measure the ground state energy in ortho-H2 relative to the first electronically excited state by Ramsey-comb laser spectroscopy on the EF1Σ+g−X1Σ+g(0,0) Q1 transition. The resulting transition frequency of 2 971 234 992 965(73) kHz is 2 orders of magnitude more accurate than previous measurements. This paves the way for a considerably improved determination of the dissociation energy (D0) for fundamental tests with molecular hydrogen.

A model presented in an accompanying work predicts that mid-IR absorption signals from methane in trace concentrations in various buffer gases detected at pressures in the 1–100 Torr range can be reduced and distorted due to depletion of the vibrational ground state if the molecules are exposed to laser powers in the tens of mW range or above. This work provides experimental evidence of such depletion in a resonant cavity under a variety of conditions, e.g. for intracavity laser powers up to 2 W and for buffer gases of N₂ or dry air, and verifies the applicability of the model. It was found that the degree of depletion is significantly larger in N₂ than dry air, and that it increases with pressure for pressures up to around 10 Torr (attributed to a decreased diffusion rate) but decreases with pressure for pressures above 20 Torr (caused by an increased collisional vibrational decay rate). The maximum degree of depletion (∼80%) was obtained for methane in N₂ at around 15 Torr. This implies that absorption spectrometry of methane can experience significant non-linear dependencies on laser power, pressure, as well as buffer gas composition. It is shown that depletion takes place also in ¹³CH₄, which verifies the applicability of the model also for this isotopologue, and that NICE-OHMS signals detected in absorption phase are less affected by depletion than in dispersion. It was concluded that the absorption mode of detection can provide concentration assessments that are virtually free of influence of depletion for intracavity powers below 0.8 W.

We measure speed-dependent Voigt lineshape parameters with temperature-dependence exponents for several hundred spectroscopic features of pure water spanning 6801–7188 cm⁻¹. The parameters are extracted from broad bandwidth, high-resolution dual frequency comb absorption spectra with multispectrum fitting techniques. The data encompass 25 spectra ranging from 296 K to 1305 K and 1 to 17 Torr of pure water vapor. We present the extracted parameters, compare them to published data, and present speed-dependence, self-shift, and self-broadening temperature-dependent parameters for the first time. Lineshape data is extracted using a quadratic speed-dependent Voigt profile and a single self-broadening power law temperature-dependence exponent over the entire temperature range. The results represent an important step toward a new high-temperature database using advanced lineshape profiles.

The germane molecule, GeH₄, is present in the atmospheres of giant planets Jupiter and Saturn. The ongoing NASA mission Juno has renewed interest in its spectroscopy, whose accurate modeling is essential for the retrieval of other tropospheric species. We present here the first complete analysis and modeling of line positions and intensities in the strongly absorbing ν₁/ν₃ stretching dyad region near 2100 cm^-1 for all five germane isotopologues in natural abundance. New infrared spectra were recorded, absolute intensities were extracted through a careful procedure and modeled thanks to the formalism and programs developed in the Dijon group. A database of calculated germane lines, GeCaSDa, has been build and is available online through the Virtual Atomic and Molecular Data Centre (VAMDC) portal and at http://vamdc.icb.cnrs.fr/PHP/gecasda.php.

The infrared spectra of GeH₄ (88.1 % of ⁷⁶GeH₄, 11.5 % of ⁷⁴GeH₄, and a minor amounts of three other stable isotopic species in the sample) were measured in the 4000–4250 cm^-1 region with a high resolution of 0.003 cm^-1 at different pressures with the Bruker IFS 125HR Fourier transform interferometer (Nizhny Novgorod, Russia) and were analyzed theoretically. The 1974 transitions with J^max. = 21 were assigned to the bands ν₁+ν₃(F₂)  and 2ν₁(A₁) of the ⁷⁶GeH₄ isotopologue. Rotational, centrifugal distortion, tetrahedral splitting, and interaction parameters for the (1010, F₂) and (2000, A₁) vibrational states were determined from the fit of experimental line positions. Influence of the (0020, A₁), (0020, E) and (0020, F₂) vibrational states on the structure of the states (1010, F₂) and (2000, A₁) is taken into account. In this case, the main resonance interaction parameters have been estimated on the basis of the local mode model and then fitted. A set of spectroscopic parameters of the effective Hamiltonian obtained from a weighted fit reproduces the initial experimental data with the d_rms=4.5*10^-4 cm^-1. The results of analogous analysis of the ⁷⁴GeH₄ isotopologue (the number of assigned transitions is 652) are presented also.

Water lines in the infrared are convenient frequency references. We present absolute positions of several H₂¹⁶O ro-vibrational transitions around 790 nm using comb-locked cavity ring-down saturation spectroscopy. Lamb dips of 6 water lines with saturation power in the range of 70–130 kW/cm² were observed and the line positions were determined with an accuracy of 25 kHz, corresponding to a fractional uncertainty of 6.6 × 10⁻¹¹. The present work demonstrates the capability to considerably improve the accuracy of the water line positions in the infrared.

The intensity and temperature dependence of four CO2 collision induced absorption (CIA) bands in two spectral regions, 1100–1600 cm^-1 and 2500^-1 have been investigated. The measurements have been performed with a Fourier Transform InfraRed (FT-IR) spectrometer operating in a wide spectral range, from 350 to 25000 cm^-1 (0.4 to 28.5 µm) with a spectral resolution of 2 cm^-1 interfaced with a high pressure-high temperature (HP-HT) absorption cell with an optical path of about 2 cm. While the integrated band intensity of allowed bands shows a linear dependence versus density, the collision-induced integrated band intensity increases quadratically with the density, due to the absorption by pairs of molecules, which allows identifying the CIA bands unambiguously. While below 300 K the binary integrated absorption coefficients exhibit a pronounced temperature dependence due to the presence of dimers, a much weaker temperature dependence has been found above 300 K. The results are important for the radiative transfer calculations of Venus’ atmosphere. The integrated band intensities of the studied bands have been calculated for Venus’ atmosphere from 40 km down to the surface by extrapolating the binary integrated absorption coefficients to the relevant temperatures.

Accurate intensity measurements were performed for several lines of the two main isotopologues of carbon dioxide, using cavity ring down spectroscopy. Absorption spectra of the R52e line at 6112.8902 cm^-1 (30014←00001 band) of ¹²CO₂ and the P6e line at 6114.8580 cm⁻¹ (30013←00001 band) of ¹³CO₂ were recorded at pressures between 15 and 50 mbar at 298 K. Line shape analysis shows that Galatry profile, taking into account Dicke narrowing of spectral lines, better describes the measured spectra at all pressures than the Voigt profile. The values of Dicke narrowing parameter for both lines were found to be significantly smaller than those predicted based on the mass diffusion constant. The values of the line strength for R52e line of ¹²CO₂ and P6e line of ¹³CO₂ were determined with an uncertainty of 0.5%. These values were found to be in good agreement with the corresponding data available in literature, in particular with the most recent ab initio calculations. The results of relative isotopic ratio ¹³CO₂/¹²CO₂ measurements are also presented in pure carbon dioxide samples and in 400 µmol/mol carbon dioxide in air samples, using cavity ring down spectroscopy.

Broadband precision spectroscopy is indispensable for providing high fidelity molecular parameters for spectroscopic databases. We have recently shown that mechanical Fourier transform spectrometers based on optical frequency combs can measure broadband high-resolution molecular spectra undistorted by the instrumental line shape (ILS) and with a highly precise frequency scale provided by the comb. The accurate measurement of the power of the comb modes interacting with the molecular sample was achieved by acquiring single-burst interferograms with nominal resolution matched to the comb mode spacing. Here we describe in detail the experimental and numerical steps needed to achieve sub-nominal resolution and retrieve ILS-free molecular spectra, i.e. with ILS-induced distortion below the noise level. We investigate the accuracy of the transition line centers retrieved by fitting to the absorption lines measured using this method. We verify the performance by measuring an ILS-free cavity-enhanced low-pressure spectrum of the 3ν₁ + ν₃ band of CO₂ around 1575 nm with line widths narrower than the nominal resolution. We observe and quantify collisional narrowing of absorption line shape, for the first time with a comb-based spectroscopic technique. Thus retrieval of line shape parameters with accuracy not limited by the Voigt profile is now possible for entire absorption bands acquired simultaneously.

Rotation-vibration  energy  levels  are  determined  for  the  electronic  ground  state  of  the acetylene  molecule, ¹²C₂H₂,  using  the  Measured  Active  Rotational-Vibrational Energy Levels (MARVEL) technique. 37,813 measured transitions from 61 publications are considered.  The distinct components of the spectroscopic network linking ortho and para states are considered separately. The 20,717 ortho and 17,096 para transitions measured experimentally are used to determine 6013 ortho and 5200 para energy levels. The MARVEL results are compared with alternative compilations based on the use of effective Hamiltonians.

Vacuum-ultraviolet (VUV) photoabsorption spectra were recorded of the A ²Σ⁺(v'=0) <-- X ²Π(v"=0), D ²Σ⁺(v'=0) <-- X ²Π(v"=0) and D ²Σ⁺(v'=1) <-- X ²Π(v"=0) bands of the OH and OD radicals generated in a plasma-discharge source using synchrotron radiation as a background continuum coupled with the VUV Fourier-transform spectrometer on the DESIRS beamline of synchrotron SOLEIL. High-resolution spectra permitted the quantification of transition frequencies, relative f-values, and natural line broadening. The f-values were absolutely calibrated with respect to a previous measurement of A ²Σ⁺(v'=0) <-- X ²Π(v"=0) (Wang et al., 1979). Lifetime broadening of the excited D ²Σ⁺(v'=0) and D ²Σ⁺(v'=1) levels is measured for the first time and compared with previous experimental limits, and implies a lifetime 5 times shorter than a theoretical prediction (van der Loo and Groenenboom, 2005). A local perturbation of the level in OH was found.

High-resolution Fourier transform spectra of the asymmetric methyl- bending and methyl-stretching bands of CH₃SH have been recorded employing synchrotron radiation at the FIR beamline of the Canadian Light Source. Analysis of the torsion-rotation structure and relative intensities has revealed the novel feature that for both bend and stretch the in-plane and out-of-plane modes behave much like a Coriolis-coupled l-doublet pair originating from degenerate E modes of a symmetric top. As the axial angular momentum K increases, the energies of the coupled “l = ±1” modes diverge linearly, with effective Coriolis ξ constants typical for symmetric tops. For the methyl-stretching states, separated at K = 0 by only about 1 cm⁻¹, the assigned sub-bands follow a symmetric top Δ(K – l) = 0 selection rule, with only ΔK = –1 transitions observed to the upper l = –1 in-plane A′ component and only ΔK = +1 transitions to the lower l = +1 out-of-plane A′′ component. The K = 0 separation for the CH₃-bending states is larger at 9.1 cm⁻¹ with the l-ordering reversed. Here, both ΔK = +1 and ΔK = –1 transitions are seen for each l-component but with a large difference in relative intensity. Term values for the excited state levels have been fitted to J(J + 1) power-series expansions to obtain substate origins. These have then been fitted to a Fourier model to characterize the torsion-K-rotation energy patterns. For both pairs of vibrational states, the torsional energies display the customary oscillatory behaviour as a function of K and have inverted torsional splittings relative to the ground state. The spectra show numerous perturbations, indicating local resonances with the underlying bath of high torsional levels and vibrational combination and overtone states. The overall structure of the two pairs of bands represents a new regime in which the vibrational energy separations, torsional splittings and shifts due to molecular asymmetry are all of the same order, creating a challenging and complex vibration-torsion-rotation coupling environment.

A ¹³C-enriched spectrum of methane (¹³CH₄) was recorded at Doppler-limited resolution (0.0044 cm⁻¹) at 80 K covering the entire Tetradecad region in the 4970–6200 cm⁻¹. In this paper we present the spectral analysis of the lower part of the ¹³CH₄ Tetradecad in the 4970–5470 cm⁻¹ region. Starting with a non-empirical effective Hamiltonian derived by high-order Contact Transformations (CT) from the ab initio potential energy surface (PES), the effective Hamiltonian parameters have been determined for this region by extending the previous DAS (Differential Absorption Spectroscopy) spectral analysis for the upper part of the Tetradecad in the 5853–6200 cm⁻¹ region. In total, 1387 rovibrational transitions were assigned belonging to five cold bands of the Tetradecad up to J_max = 11. Their positions were fitted with an rms deviation of 1.6 × 10⁻³ cm⁻¹. Measured line intensities for 737 transitions were modeled using the effective dipole transition moments approach with an rms deviation of about 10%. Finally, the observed transitions were incorporated to fit simultaneously the ¹³CH₄ Hamiltonian parameters for the {Ground state / Dyad / Pentad / Octad / Tetradecad} system and the dipole moment parameters for the {Ground state - Tetradecad} system.

To improve the understanding of temperature-dependence laws of spectral line shape parameters, spectra of the ν₃ rovibrational band of CO₂ perturbed by 10, 30, 100, 300 and 1000 mbar of N₂ were recorded at nine temperatures between 190 K and 330 K using a 22 cm long single-pass absorption cell in a Bruker IFS125 HR Fourier Transform spectrometer. The spectra were fitted employing a quadratic speed-dependent hard collision model in the Hartmann–Tran implementation extended to account for line mixing in the Rosenkranz approximation by means of a multispectrum fitting approach developed at DLR. This enables high accuracy parameter retrievals to reproduce the spectra down to noise level and we present the behavior of line widths, shifts, speed-dependence-, collisional narrowing- and line mixing-parameters over this 140 K temperature range.

Approximately seventy isolated and overlapping methane absorption lines in the 5647 − 6164 cm⁻¹ spectral region were processed with seven line profiles accounting for all main line shape forming physical mechanisms in different combinations. It was shown that at low methane pressures the conventional Nelkin–Ghatak line profile gives satisfactory results in retrieving line parameters as opposed to the Voigt profile. It was found that most of the considered lines do not interfere. The FTS instrumental function elimination technique based on Doppler-broadened line's records was applied, and its applicability was proved.

We report experimental measurements of spectral line shape parameters (air-broadened width, shift, and line mixing coefficients) for several transitions in the ν₃ Q branch of methane in the 3000–3023 cm⁻¹ region. 13 high-resolution, room temperature laboratory spectra of pure methane and air-broadened methane recorded with two different Fourier transform spectrometers are fitted. 12 of these spectra were acquired at 0.01 cm⁻¹ resolution with the McMath-Pierce FTS at the National Solar Observatory on Kitt Peak, and one higher-resolution (∼0.0011 cm⁻¹) low pressure methane spectrum was obtained with the Bruker IFS-120HR FTS at the Pacific Northwest National Laboratory, in Richland, Washington. All the spectra were obtained using high purity natural samples of CH₄ and lean mixtures of the same natural CH₄ in dry air. For the 12 spectra recorded at Kitt Peak, three different absorption cells (L = 5, 25 and 150 cm) were used while the methane spectrum at PNNL was obtained using a 19.95 cm long absorption cell. For the analysis, an interactive multispectrum nonlinear least squares fitting software was employed where all the 13 spectra were fitted simultaneously. An accurate and self-consistent set of line parameters were determined by constraining a few of those for severely blended transitions. Line mixing was measured for 14 transition pairs for the CH₄-air collision system. A constant speed dependence parameter, consistent with measured speed dependence values obtained in other methane bands, was applied to all the transitions included in the fitted region. The present measurements are compared to values reported in the literatur

In this work, we show that precise predictions of the shapes of H₂O rovibrational lines broadened by N₂, over a wide pressure range, can be made using simulations corrected by a single measurement. For that, we use the partially-correlated speed-dependent Keilson–Storer (pcsdKS) model whose parameters are deduced from molecular dynamics simulations and semi-classical calculations. This model takes into account the collision-induced velocity-changes effects, the speed dependences of the collisional line width and shift as well as the correlation between velocity and internal-state changes. For each considered transition, the model is corrected by using a parameter deduced from its broadening coefficient measured for a single pressure. The corrected-pcsdKS model is then used to simulate spectra for a wide pressure range. Direct comparisons of the corrected-pcsdKS calculated and measured spectra of 5 rovibrational lines of H₂O for various pressures, from 0.1 to 1.2 atm, show very good agreements. Their maximum differences are in most cases well below 1%, much smaller than residuals obtained when fitting the measurements with the Voigt line shape. This shows that the present procedure can be used to predict H₂O line shapes for various pressure conditions and thus the simulated spectra can be used to deduce the refined line-shape parameters to complete spectroscopic databases, in the absence of relevant experimental values.

A two-channel thermal dissociation cavity ring down spectroscopy (CRDS) instrument has been built for in situ, real-time measurement of NO₂ and total RNO₂ (peroxy nitrates and alkyl nitrates) in ambient air, with a NO₂ detection limit of 0.10 ppbv at 1s. A 6-day long measurement was conducted at urban site of Hefei by using the CRDS instrument with a time resolution of 3 s. A commercial molybdenum converted chemiluminescence (Mo-CL) instrument was also used for comparison. The average RNO₂ concentration in the 6 days was measured to be 1.94 ppbv. The Mo-CL instrument overestimated the NO₂ concentration by a bias of +1.69 ppbv in average, for the reason that it cannot distinguish RNO₂ from NO₂. The relative bias could be over 100% during the afternoon hours when NO₂ was low but RNO₂ was high.

Using a tunable frequency-stabilized CO₂ laser, the pressure dependences of unsaturated absorption coefficients (AC) are measured in pure carbon dioxide in the pressure range from 5 to 30 Torr, where the spectral line shape is described by the Voigt profile. The absorption coefficients are measured in the centers of R(8), R(22), R(34), P(22), and P(36) spectral lines of the 10⁰0–00⁰1 transition in the temperature range 300–700 K. By means of the least-squares method, the inverse problem is solved for the system of equations for AC at different pressures in the temperature range under study. The self-broadening coefficients2−and the probabilities of spontaneous emission A _ik are derived. A new formula is proposed for CO2−CO(T) dependence.

We propose a novel approach to cavity-ring-down-spectroscopy (CRDS) in which spectra acquired with a frequency-agile rapid-scanning (FARS) scheme, i.e., with a laser sideband stepped across the modes of a high-finesse cavity, are interleaved with one another by a sub-millisecond readjustment of the cavity length. This brings to time acquisitions below 20 s for few-GHz-wide spectra composed of a very high number of spectral points, typically 3200. Thanks to the signal-to-noise ratio easily in excess of 10 000, each FARS-CRDS spectrum is shown to be sufficient to determine the line-centre frequency of a Doppler broadened line with a precision of 2 parts over 1011, thus very close to that of sub-Doppler regimes and in a few-seconds time scale. The referencing of the probe laser to a frequency comb provides absolute accuracy and long-term reproducibility to the spectrometer and makes it a powerful tool for precision spectroscopy and line-shape analysis. The experimental approach is discussed in detail together with experimental precision and accuracy tests on the (30 012) ← (00 001) P12e line of CO₂ at ∼1.57 μm.

In this work the high resolution synchrotron radiation Fourier transform spectrum in the range1180-1300 cm^-1 corresponding to the COH- bending vibrational mode has been recorded and analyzed. The spectrum shows a structure analogous to a parallel band. Since the COH bending motion is one of the main contributors to the asymmetry in the torsional hindering potential barrier, the torsional barrier height in the excited state is expected to be quite different from that of the ground state. This makes the spectrum to spread over a wide region. Although the spectrum corresponding to the P- and R- branch looks very complicated, the Q-branches are well resolved and can be identified without much difficulty. It was possible to assign the spectra for K=0 to 10 for the trans- (e₀) species. The interesting feature of the spectra is the absence of the lines for two other lower lying symmetry species e₁ and o₁. The spectra due to any perpendicular transitions were absent as well. The analysis of the spectrum has been carried out to obtain precise term values and molecular parameters in the excited COH- bending state. The results will be shown valuable to assign similar spectra for the methanol-D₂. This work represents the first reported high resolution study of this illusive vibrational mode in methanol-D₁.