Rotationally inelastic rates over a wide temperature range based on an energy corrected sudden–exponential-power theoretical analysis of Raman line broadening coefficients and Q branch collapse

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Abstract
We study the ability of the energy corrected sudden (ECS) scaling law associated with a hybrid exponential‐power (EP) fitting law for the basis rate constants to model the rotational dependence of isotropic Raman linewidths. We determine the temperature dependence of the hybrid law (EP) parameters and give several applications for various molecular collisional systems over a wide temperature range. In particular, we find that the ECS–EP law gives a very good description of both rotational and temperature dependences of the Raman line broadening coefficients of N2 perturbed by H2O contrary to the ECS–P law. For all the collisional systems studied the ECS–EP law is found very suitable to describe the line broadening coefficients. We give a complete set of ECS–EP parameters for these collisional systems which play an important role in coherent anti‐stokes Raman spectroscopy thermometry. We also test the ability of the ECS–EP law to predict accurate collapsed Q branch at high density. An application performed on the Raman Q branch of pure N2 at high density demonstrates that the ECS–EP law properly models the rates of state‐to‐state rotational energy transfer. The overall collisional line shift obtained from the collapsed Q branch is in perfect agreement with low pressure measurements on isolated lines.