Measurements of H₂O broadened by CO₂ line-shape parameters: Beyond the Voigt profile

H₂O is an important molecule in the quest to better understand the evolution of solar system. In the study of Venus and Mars CO₂-rich atmospheres (around 96 % of their composition) and because of the space instruments constant improvements, the planetary community needs spectroscopic data as accurate as possible. Continuing from our previous study [JQSRT 231, 126(2019)], new spectra of H₂O perturbed by CO₂ were measured with our new experimental set-up in the 2.7 µm region to compare with the previous results. After the improvement in the determination of the partial pressure of water vapor, the line parameters were then determined with a multispectrum fitting procedure using a Voigt profile in the same way as in [JQSRT 231, 126(2019)]. This led to characteristic W-shape residuals that have been improved using beyond-Voigt profiles. Our investigation showed that considering the speed dependence of collisional line parameters is essential to obtain better line-shape parameters in the considered experimental conditions.