Fractal aggregation: Scaling of fractal dimension with stability ratio

A scaling relation between fractal dimension and stability ratio is demonst rated for a charged polystyrene colloid undergoing aggregation. The stabili ty ratio, i.e., the inverse collision efficiency, or inverse sticking proba bility, is systematically decreased by reducing the electrostatic barrier t o aggregation. Fractal dimensions are measured by static light scattering, while stability ratios are evaluated from early-time aggregation kinetics ( t < 10t(1/2)) using dynamic light scattering. The fractal dimension for the model hydrophobic colloid investigated increases monotonically with stabil ity ratio, reflecting a continuous increase in particle packing density as the sticking probability is reduced.