Dynamic light scattering in turbid suspensions: An application of different cross-correlation experiments

Abstract

The ability to characterize colloidal suspensions by means of dynamic light scattering is limited to systems with negligible contributions from multiple scattering. For larger particle sizes with high scattering contrast this immediately limits the technique to very low concentrations. A very interesting solution of this problem is to suppress multiple scattering in dynamic light scattering experiments using various cross-correlation schemes. Based on these considerations we have constructed a so-called 3D cross-correlation experiment with which we are able to characterize extremely turbid suspensions. We have tested the feasibility of these experiments with well defined model systems such as suspensions of monodisperse and bimodal latex particles with relatively high volume fractions. The results are very promising and demonstrate unambiguously that such systems can be quantitatively characterized by means of dynamic light scattering methods without having to resort to high dilution.