Multiple contact kernel for diffusionlike aggregation

The Brownian kernel is usually assumed to describe pure diffusion-limited cluster-aggregation processes. In this work, we show that this assumption is correct for simulated data. For experimental data, however, significant deviations were observed although the system was aggregated at an electrolyte concentration well above the critical coagulation concentration. This indicates that residual cluster-cluster interactions are not completely absent in real experimental systems. In order to improve the description of the experimental data, we developed a kernel that considers a monomer-monomer sticking probability explicitly and accounts for the possibility of multiple monomer-monomer contacts in the cluster collision area. The proposed kernel agrees excellently with the experimental cluster-size distribution and the corresponding scaling function.