Refined line-shape parameters for CO lines broadened by air predicted from requantized classical molecular dynamics simulations

Abstract

Line-shape parameters and their temperature dependences for CO lines broadened by air have been predicted using requantized classical molecular dynamics simulations. The latter were carried out for mixtures of CO in air for five temperatures ranging from 200 K to 400 K, all at a pressure of 1 atm. For each temperature and pressure condition, various Doppler widths have been considered enabling the calculations of absorption spectra for a large range of collisional to Doppler widths ratios. The simulated spectra were then fitted with the speed-dependent Nelkin-Ghatak, speed-dependent Voigt and Voigt profiles, providing the corresponding line-shape parameters. First-order line-mixing parameters were also retrieved. The temperature dependences of these parameters were then determined using a single power law. Comparisons between the predicted parameters and available experimental values as well as those of the latest edition of the HITRAN database show good agreements. The theoretically predicted values and their temperature dependences can thus be used for the modeling of the absorption spectrum of CO in air and to complete spectroscopic databases when accurate experimentally-determined values are not available.