Oxygen- and air-broadening coefficients for the CH3I v(6) fundamental at room temperature

CH3I-oxygen line-broadening coefficients at 296 K are calculated for the R-R, R-P, P-R, P-P, (R)Q and (P)Q sub-branches of the v(6) band in a wide range of rotational quantum numbers (0 <= J <= 70, K <= 20 by a semi-classical and a semi-empirical methods. The computed values compare very favourably with the available experimental data and therefore can be safely employed as estimates of broadening coefficients missing in databases for high J and K. The theoretical data for CH3I-O-2 are further combined with the previously calculated room-temperature CH3I-N-2 line-broadening coefficients to obtain the air-broadening values required for atmospheric applications. The calculated results demonstrate an excellent consistency with both existing sets of CH3I-air measurements. As the vibrational dependence of CH3I oxygen-broadening coefficients is shown to be small, similarly to the nitrogen-broadening case, the CH3I-O-2 and CH3I-air line-broadening coefficients calculated for the v(6) fundamental can be used for other perpendicular and parallel bands. (C) 2021 Elsevier Ltd. All rights reserved.