Surface Adsorption of Light Gas Atoms

Abstract

The adsorption on solid surfaces of very light gas atoms is reconsidered. A variational wavefunction is constructed for the quantum-mechanical ground state of the adsorbed atom, and improved values of adsorption energies are calculated for a few cases. The surface mobility at low temperatures is determined quantum mechanically, by use of the variational ground-state wavefunction. Simple analytic approximations are derived for the sticking coefficient S and the accommodation coefficient α for gas atoms impinging on a surface. A few previous accurate calculations and some experiments are used to derive some general analytic semiempirical formulas for S and α as a function of the gas temperature. Surface recombination of diatomic molecules from two adsorbed atoms is considered briefly.