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

Abstract

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 comparisons 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.