First-layer formation in ballistic deposition of spherical particles: Kinetics and structure

Abstract

We present a computer simulation and theoretical study of a ballistic deposition process in which spheres are incident on a planar surface. Each incoming sphere follows a path of steepest descent which may involve rolling over the surface of preadsorbed spheres. All particles reaching a stable, elevated position are removed. The frequency of the various rolling mechanisms are evaluated as a function of coverage. The addition mechanism generates clusters of connected spheres by accretion and coalescence. We evaluate the dependence of the cluster size distribution and coalescence probability on coverage. Various peaks in the radial distribution function of the deposited layer provide a signature for the deposition mechanism. The asymptotic approach to saturation is shown to be of the form θ∞−θ(t) ∝exp[−(4/π)Smt]/t2, where Sm=√3/2 is the smallest possible target area. The expression is shown to be consistent with the simulation results. Interpolants, which accurately describe the time-dependent coverage over the entire coverage range, are developed based on the exact expressions for the asymptotic and low coverage kinetics.