Characterization of surfaces by low-energy helium scattering

Abstract

An experimental apparatus is described which permits excellent sensitivity and energy resolution in atomic and molecular beam surface scattering experiments. It is suggested that the Boxcar Integrator, a low cost, commercial instrument, is ideally suited to these experiments and, for helium scattering, yields more information than the conventional lock-in amplifier technique. Preliminary data on low-energy helium scattering from unoriented W(100) facets, produced by annealing a tungsten ribbon, shows sharp diffraction effects due to a surface structure grating at least 70 Å in characteristic size. Applications to inelastic scattering studies are briefly discussed.