The dependence of accommodation coefficient on surface temperature

The dependence of energy accommodation coefficients of inert gases on clean metal surfaces is analyzed in the framework of classical lattice theory. It is found that a Knudsen layer must exist next to the surface to adjust the gas molecular velocity distrivution to surface conditions. At energies below the well-depth, the accommodation coefficient slope is inversely proportional to the square root of the temperature; at energies above the welldepth, the accommodation coefficient is independent of surface temperature.