Evidence of scattering anisotropy effects on boundary conditions of the diffusion equation

Abstract

We present experimental evidence that the diffusion process close to the boundary is fundamentally different from the bulk diffusion in the sense that it is affected by the scattering properties of the individual centers. Systematic measurements show a nontrivial behavior of the extrapolation length ratio on the scattering anisotropy of individual particles. The results are compared with other works and are supported by an independent Monte Carlo simulation. A simple analytical model that emphasizes the influence of the last scattering event successfully describes the results.