2024 Articles

The j and k dependencies of N2-, O2-, and air-broadened halfwidths of the CH3CN molecule

Ma, Qiancheng; Boulet, C.

The N2-, O2-, and air-broadened halfwidths of CH3CN lines in the parallel ν4 band have been calculated, along with the relaxation matrices W. These calculations employ our modified and refined versions of the Robert- Bonamy formalism and use all potential parameters from the literature without adjustments. Extensive com- parisons between the predicted N2-broadened halfwidths in the qR and qP branches from the models at T = 296 K and experimental measurements are presented, showing that our latest model very closely matches the measurements. For the qQ branch, where measurements are unavailable, we compare our N2-broadened halfwidths with the converted air-broadened data from HITRAN 2008, obtaining similarly good agreement. The variation in the j and k dependencies of the N2-broadened halfwidths is discussed in detail. Additionally, the theoretically determined conversion factor from N2- to air-broadening is provided. Finally, based on our theoretical calculations of N2-broadened halfwidths of the qR(j,3) lines at five different temperatures, ranging from 250 K to 350 K, the temperature exponent N is determined and its dependence on j is analyzed.