N2-broadening coefficients of CH3CN rovibrational lines and their temperature dependence for the Earth and Titan atmospheres

Theoretical nitrogen-broadening coefficients and their temperature exponents for methyl cyanide lines in parallel (ΔK = 0) bands are calculated by a semi-empirical approach suitable for CH3X-type absorbers with large dipole moments. Together with the standard four-parameter correction factor determined from fitting on experimental line widths for each fixed K and requiring an extrapolation for higher K inaccessible experimentally, a new form accounting explicitly for the K-dependence and reducing the number of required parameters is proposed and successfully tested. Extensive (0 ⩽ J ⩽ 70, 0 ⩽ K ⩽ 20) R- and P-line lists are provided for the Earth and Titan atmosphere temperature ranges, which could be useful for atmospheric/astrophysical applications and spectroscopic databases.