Kinetic Model Analysis of Light Scattering by Molecular Gases

Density fluctuations in a polyatomic gas are studied with a kinetic description assuming constant relaxation times. Exact results for the initial-value problem are applied to laser scattering experiments. It is shown that the spectral distribution of scattered light can be predicted in terms of specific heats, transport coefficients, and measured values of the rotational relaxation number. Explicit considerations of CO2 spectra suggest that the technique of laser scattering is potentially useful for studying rotational relaxation phenomena. The kinetic calculations are supplemented by hydrodynamical analysis. It is found that internal relaxation plays a significant role even at small scattering angles.