Analysis of observables in diagonally polarized light scattering experiments

Abstract

We analyze the polarization of light scattered from an ensemble of stationary, randomly oriented molecules of arbitrary size, for ‘‘diagonally’’ polarized incident light (linearly polarized at ±45° to the scattering plane). The results are expressed in terms of the ‘‘diagonal modulation,’’ the change in scattered intensity when the incident polarization switches from +45° to −45°. We use the exact nonrelativistic operators for the interaction of light and matter, and we use no wave function approximations. The diagonal modulation is expressed as a superposition of four independent observables, which may be separated by polarization filters in the observation channel. Three of these are found to posses interesting characteristics after the classical orientation average is taken: (a) they vanish when the damping constants of the molecule are set to zero; and (b) they vanish in the limit of a dipolar scattering tensor. This analysis therefore suggests experiments in which combinations of damping constants and higher transition multipoles might be directly observed.