Efficiencies of Diffusing Spherical Particles : Hydrodynamic , Van Der Waals and Electrostatic Forces

I. ABSTRACT A practical 1 imitation ·of the application of Smoluchowski 1 s classical estimate for the collision probability of two diffusing spherical particles in Brownian motion is the non-consideration of interparticle forces. For suspended particles in water such forces can arise from the disturbance the particle causes in the fluid {hydrodynamic forces), from the cloud of ions which surround an electrically charged particle (double layer forces} or they can be of molecular origin (van der Waals forces). In this paper corrections to Smoluchowski 1 s collision probability are computed when such forces operate between two approaching particles of various sizes . Results for several values of the van der Waals energy of attraction and the ionic strength of the electrolyte are presented in a way convenient for particle col lis ion mode 1 i ng.