Precise modelling of infrared absorption by carbon dioxide is of primary importance for radiative transfer calculations in CO
-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
in a large spectral region range, from 750 to 8500 cm
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
finite collision duration (non impact) effects, empirical approximations are proposed in order to model the far wings.
Papers with the following subject areas are suitable for publication in the Journal of Quantitative Spectroscopy and Radiative Transfer:
As the world’s leading publisher of science and health information, Elsevier serves more than 30 million scientists, students, and health and information professionals worldwide. We are proud to play an essential role in the global science and health communities and to contribute to the advancement of these critical fields. By delivering world-class information and innovative tools to researchers, students, educators and practitioners worldwide, we help them increase their productivity and effectiveness. We continuously make substantial investments that serve the needs of the global science and health communities.
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.
