Dynamic light scattering from concentrated particle dispersions

Abstract

Using dynamic light scattering, we studied the properties of light scattered from latex dispersions over a very broad range of volume fraction of latex, φ, between very dense (φ ∼ 0.35) and very dilute (φ ∼ 10⁻⁶) dispersion. We show that, at intermediate φ, the spectrum of decay times obtained by Laplace inversion of the measured autocorrelation function is bimodal. The slow component, corresponding to single scattering, can be determined up to volume fraction of latex of φ ∼ 0.01. In these dense dispersions the second virial coefficient of diffusion, k_D, is about two orders of magnitude larger than the value expected for hard spheres. For volume fraction of spheres above φ ∼ 0.05, the limit of strong multiple light scattering is attained, where diffusive transport of light is observed.