LEIS: A reliable tool for surface composition analysis?

Different single and polycrystalline surfaces of Cu and Ag have been investigated by time-of-flight low-energy ion scattering using 4He+ ions. The fraction of ions that survived single scattering from the outermost surface layers, P+, was measured in different neutralization regimes. At low energies, a distinct difference in P+ was observed for non-equivalent Cu crystal surfaces for projectiles backscattered in a single collision. The polycrystalline surface was found to exhibit similar neutralization behaviour as the (1 1 1) single crystal surface. At higher energies, P+ shows a strong dependence on the angular orientation of the single crystal. The impact of these findings on quantitative surface composition analysis by LEIS is discussed.