Dynamical scaling of fractal aggregates in dense colloidal solutions

We present results from a detailed Monte Carlo study of a two-dimensional off-lattice system of a dense colloidal solution undergoing a diffusion-limited-cluster-aggregation (DLCA) process. We find that the dynamical structure factor, S(k,t), scales with the characteristic linear size of the aggregates, ${\mathit{R}}_{\mathit{g}}$(t), according to S(k,t)=${\mathit{R}}_{\mathit{g}}^{{\mathit{D}}_{\mathit{f}}}$ F(${\mathit{kR}}_{\mathit{g}}$(t)), where ${\mathit{D}}_{\mathit{f}}$ is the fractal dimension of the clusters and F is a universal scaling function. We have verified that the shape of this scaling function compares well with the experimentally obtained scaling function. Although this behavior is similar to the dynamical scaling law found in systems undergoing spinodal decomposition, we find that some details of the evolution process of the DLCA model are quite different from the dynamics of phase-separating systems.