Computer simulations were used to study the diffusion of monolayer films confined between atomically structured uncharged mica surfaces. Diffusion parallel to the walls was found to be anisotropic due to the influence of the atomically structured surfaces. When the surfaces were aligned perfectly the fluid occupied isolated regions of the pore space, diffusion was the same in all lateral directions and was a minimum. If one of the surfaces was shifted laterally in the x-direction by half of a unit cell, diffusion was enhanced in the x-direction along conduits formed by the overlapping potential energy fields of the surfaces. This confirmed that diffusion of a confined simple fluid in a nanoscale slit-pore was tunable in terms of direction and magnitude by control of the relative alignment of the surfaces.

Computer Simulation of Anisotropic Diffusion in Monolayer Films in Mica Slit Pores.  Su, Z., Cushman, J.H., Curry, J.E.: Journal of Chemical Physics, 2003, 118, 1417