Multiple scattering from a system of Brownian particles

We consider the total multiple-scattered light field from a system of Brownian diffusing particles. We assume the correlation function is due to contributions from all the independent single-scattering events leading to the multiple-scattered field. We then assume the relative magnitudes of the various orders of the multiple-scattered light are given by the Poisson distribution. For particles of radius $r\ll \lambda$, $\lambda$ being the wavelength of light, we arrive at expressions for the depolarization ratio and the polarized and depolarized linewidths as functions of the average number of scattering events $\overline{n}=\sigma \rho x$, where $\sigma$ is the single-particle scattering cross section, $\rho$ is the particle concentration and $x$ is a distance related to the scattering volume size. We give experimental data to support our contentions.