Line coupling and line mixing effects on calculated widths of symmetric-top molecules with the k-degeneracy: A theoretical study of N₂-, O₂-, and air-broadened lines of CH₃I

Boulet, C.; Ma, Qiancheng

Calculations of the N₂-, O₂-, and air-broadened widths, together with their temperature dependence exponents have been made for transitions of CH3I in the ν₅ and ν₆ bands. The calculations are based on a semi-classical line shape formalism developed by the current authors through modifying and refining the Robert-Bonamy formalism. In recent years, we have applied this formalism for linear molecules, symmetric-top molecules with inversion symmetry, and asymmetric-top molecules. For symmetric-top molecules with the k degeneracy such as CH₃I, the formalism has a new feature. In this case, one should consider each of the CH₃I transitions labeled by no zero kᵢ or k_f as a doublet. Then, one needs to consider the effects of the line mixing process between these two components. Comparisons of our theoretical predictions with some data available demonstrate a very reasonable agreement. Finally we propose new experiments at higher perturber pressures that would enable one to check the theoretically calculated relaxation matrices and to extend the analysis to the inter-doublet mixing effects.


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Also Published In

Journal of Quantitative Spectroscopy and Radiative Transfer

More About This Work

Academic Units
Applied Physics and Applied Mathematics
Published Here
June 6, 2022