Light scattering and diffusion in suspensions of strongly charged particles at low volume fractions

Abstract

The perturbation approach of Barker and Henderson is applied to some dynamic processes in suspensions of charged Brownian particles. Analytical formulae are obtained for the first order correction of the diffusion coefficient, and sedimentation velocity, with respect to the particle volume fraction. For this purpose, the perturbation approach is combined with the theory of Felderhof. In the case of strongly charged particles (i.e. high surface potential) a simple computation procedure, involving the nonlinear Poisson-Boltzmann equation, is developed. The angular dependencies of the static and dynamic structure factors are also examined. The perturbation method allows the derivation of analytical formulae for the latter, from the general expressions of Ackerson, and Pusey and Tough. Some comparisons with numerical calculations are presented. Light scattering experiments were performed, and are analyzed by means of the proposed model.