Particles of different sizes diffusing over an entropic barrier

Abstract

The diffusion of particles over an entropic potential barrier was investigated. We have considered the temperature dependence of the noise-induced escape rate of Brownian particles of different sizes between two distinct regions in a two-dimensional enclosure through a narrow bottleneck. An effective entropic potential in reduced dimension is obtained by varying the cross-section of confinement. The results of numerical integration indicate that (1) the non-Arrhenius behavior of the transition rate based on the entropy-dominated regime in the presence of an interplay of gravitational bias and thermal motion is observed and (2) in the Arrhenius region the escape rate exhibits negative correlation with the particle size under the combined action of variational size (internal cause) and relatively changed boundary (external cause).