Dynamic Scaling of Cluster-Mass Distributions in Kinetic Colloid Aggregation

The cluster-mass distributions produced in the kinetic aggregation of aqueous gold colloids are measured over an extended range of masses for two limiting kinetic regimes, diffusion-limited (DLA) and reaction-limited (RLA) aggregation. Markedly different distributions are found, with DLA having a peaked distribution, while RLA has a power-law distribution. In both cases the distributions are shown to exhibit dynamic scaling, as has recently been predicted. The data are interpreted with the Smoluchowski equations, and are used to determine the form of the appropriate kernel for each regime.