Temporal Autocorrelation Function of Light Scattered from Aggregated Particles in a Dense Colloidal Suspension

Abstract

We have investigated a temporal amplitude autocorrelation function of multiply backscattered light from aggregated particles in a dense colloidal suspension. It is shown that the measured amplitude autocorrelation function for aggregated particles deviates from the theory of diffusing wave spectroscopy obtained for the multiple light scattering from homogeneously dispersed particles. We introduce a sum of temporal amplitude autocorrelation functions of the single and multiple scatterings as a model of the temporal autocorrelation function. The temporal autocorrelation functions of the single and multiple scatterings can be estimated by means of fitting the experimental data to the model function. Reliable particle sizing of clusters in the dense medium can be performed by employing the multiple scattering autocorrelation function in the short elapsed time and the single scattering autocorrelation function in the long elapsed time from the time when particles begin aggregating. Consequently, we propose a new monitoring method of the particle aggregation and a particle sizing method of clusters in the dense colloidal suspension.