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

Abstract Theoretical nitrogen-broadening coefficients and their temperature exponents for methyl cyanide lines in parallel (Δ K  = 0) bands are calculated by a semi-empirical approach suitable for CH 3 X-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.

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