Molecular polarizabilities in gases and liquids – induced interactions in liquids – Calculations from classical and revised expressions

Abstract

A comparison of the optical mean molecular polarizability ᾱ and of the molecular polarizability anisotropy γ2 between gases and liquids, based on reliable measurements is made on twelve compounds. The determinations through the spherical cavity model indicate slight decreases in ᾱ and large deviations in γ2 values from gases to liquids. A large decrease in γ2 values is observed when a corrected formula is used. It is shown by a simple electrostatic bimolecular interaction scheme that the apparent decreases observed in liquids are due to the short distance mutual interactions between the molecular dipole moments induced by the electric field of the incident optical wave. Detailed calculations are made by using the ellipsoidal cavity model, which includes the induced interactive effects in a consistent macroscopic way. They lead to ᾱ and γ2 values in liquids which are in agreement with the gas values in the case of a corrected light scattering formula. On the contrary the classical formula gives inconsistent high values. These results show the prevalence of the previously established corrected formula, and bring informations about the origin of the apparent deviations from gases to liquids.