Light Scattering from Binary Mixtures of Monatomic and Polyatomic Gases

Abstract

The spectral distribution of light scattered by microscopic thermal fluctuations about equilibrium is calculated for a binary mixture of monatomic and polyatomic gases. The linearized hydrodynamic equations of the irreversible thermodynamic theory of mixtures are supplemented by a relaxation equation for the dynamic pressure of the polyatomic gas. The results show that the relaxation equation has great influence for mixtures in which the mass of the monatomic particle is lighter than the mass of the polyatomic molecule providing that the concentration of the polyatomic gas is greater than that of the monatomic one. As an application the spectra of light scattered from mixtures of He-CH 4 are determined.