Determination of the lateral potential energy surface of single adsorbed atoms and molecules on single crystal surfaces using helium atom scattering

The lateral potential energy surface for adsorbed atoms and molecules is important for a detailed understanding of diffusion, sliding friction, catalysis, and molecular beam epitaxy. In this brief review, it is shown that the analysis of quasi-elastic helium scattering data, in addition to the complementary inelastic results for parallel translational vibrations, leads to a detailed description of the potential energy surface and the accompanying friction parameter describing energy transfer between the adsorbed particle and the surface. Several recent examples of the application of helium atom scattering to this determination are presented for Na and CO on Cu(001) and CO and Xe on Pt(111). (C) 1999 Elsevier Science B.V. All rights reserved.