Surface light-induced drift in porous media.

Abstract

Diffusion and flow of gases in porous media have attracted considerable attention for many decades [1]. Interest in such research has been motivated by its many fields of application, such as surface catalysis, gas separations, soil physics, etc. Gas flows often arise here due to the difference in gas pressure or concentration between the opposing surfaces of the porous medium. In the following report, gas flows in porous media, caused not by the concentration or pressure gradients but by Surface Light-Induced Drift (SLID) [2–5], are discussed. Unlike the former case, the flow of a gas now becomes selective. Namely, one can force only the molecules of the resonant gas through the porous membrane, while leaving the other components untouched. It implies possible benefits in using the SLID for gas separations. Also, due to a high surface/volume ratio, porous media can be especially favorable for studying the state-specificity of surface chemical reactions [4] and catalysis.