Binary collision-induced light scattering by isotropic molecular gases

Abstract

An experiment to measure the two-body collision-induced light scattering spectrum of Ar, CH₄, CD₄, CF₄ and SF₆ is described. Contrary to previous studies, the argon spectral intensity is shown to exceed that of the predictions of the first order dipole-induced-dipole model for the pair polarizability anisotropy. It is demonstrated empirically that this intensity can be accounted for by second-order quantum mechanical effects. The spectral profile is analysed in terms of various modifications to the pair polarizability. The main object of this study is to provide a basis for comparison with the molecular spectra described in paper II of this series.