HINDERED DIFFUSION IN SLIT PORES - AN ANALYTICAL RESULT

An analytical result for the hindered diffusional mobility of a spherical particle in a slit pore is derived using an asymptotic matching technique and published expressions for the enhanced viscous drag on the particle caused by the flat walls. A hard sphere-hard wall potential is assumed for the interaction between the particle and pore wall. The mobility is presented as a regular expansion in the parameter lambda and is correct to O(lambda3), where lambda is the ratio of particle radius to half-width of the pore. Our result agrees quantitatively with published numerical evaluations of the mobility up to lambda almost-equal-to 0.5. The derivation is sufficiently general that it allows for inclusion of nonsteric interactions between the particle and the pore wall.