We show that there are two regimes of irreversible, kinetic aggregation of aqueous colloids, determined by the short-range interparticle potential, through its control of the sticking probability upon approach of two particles. Each regime has different rate-limiting physics, aggregation dynamics, and cluster-mass distributions, and results in clusters with different fractal dimensions. These results set limits on the fractal dimension, $d_f$, for gold aggregates of $1.75<~d_f<~2.05$ (±0.05).

• Received 26 November 1984

DOI:https://doi.org/10.1103/PhysRevLett.54.1416