Light scattering and sound propagation in polyatomic gases with classical degrees of freedom

In this work we analyze time-dependent problems like sound propagation and light scattering in dilute polyatomic gases with classical internal degrees of freedom by using a kinetic model of the Boltzmann equation that replaces the collision operator with a single relaxation-time term. Comparison of the theoretical results with available experimental data shows that the model equation can be used to describe the acoustic properties and the light scattering spectrum of dilute polyatomic gases as long as the external oscillation frequency is smaller than the frequency required for the translational and the internal degrees of freedom to come to thermal equilibrium.