Abstract: The dynamic light scattering has been a powerful tool in measuring the size of a cluster produced by particle aggregation. This technique can be applied to only tenuous or diluted media since it has been developed on the basis of the single scattering theory. In the recent years, in situ monitoring of the aggregation process in dense scattering media has been needed in the biological diagnostics and chemical industry. We investigate a temporal autocorrelation function of light scattered multiply from aggregated particles in dense colloidal suspensions. In the experiments, the particle distribution was controlled by adding the NaCl solution to the colloidal suspension of polystyrene latex beads at 10% volume fraction. It is shown that the temporal autocorrelation function is composed from the contributions of single and multiple scatterings of light. The relaxation time of the temporal autocorrelation function increases as the aggregation of particles progresses and, therefore, its variation is related with the growth of clusters. Moreover, we estimate the number of particles included inside one cluster using the decreasing rate of the temporal autocorrelation function of the single or the multiply scattered light. As a result, the components of single and multiple scatterings of light are available for the measurements of the clusters composed from a few particles and of many particles, respectively. !14
展开▼
