Light-scattering predictions in the two-temperature regime for disparate-mass gas mixtures

Predictions are obtained for light-scattering spectra for disparate-mass gas mixtures at wave numbers such that species temperature separation produces strong deviations from hydrodynamic predictions. Recent light-scattering experiments in xenon-helium mixtures by Letamendia show good qualitative agreement with the present approximate predictions, thus providing the first experimental confirmation of the existence of a two-temperature regime in disparate-mass neutral gases. Physical reasons are suggested for the strong disagreement between two-temperature and hydrodynamic spectral predictions in the two-temperature regime.