Thermal equilibrium of a Brownian particle with coordinate dependent diffusion: comparison of Boltzmann and modified Boltzmann distributions with experimental results

Abstract: In this paper we compare the Boltzmann distribution with a modified Boltzmann distribution, that results from an It^o-process considering thermal equilibrium of a Brownian particle with coordinate dependent diffusion, in the light of an existing experiment. The experiment was reported in 1994 by Faucheux and Libchaber. The experiment made use of direct tracking of diffusion of Brownian particles near a wall. Results of this experiment allows us to compare the Boltzmann and the modified Boltzmann distribution without making use of any adjustable parameter. A comparison of these two distributions with the experimental results lends support to the consideration of thermodynamic equilibrium of a Brownian particle with coordinate-dependent diffusion to be an It^o-process.