FOCUSING OF HE+ IONS ON SEMICHANNEL PLANES IN THE PT(111) SURFACE

Focusing of scattered ions on semichannel planes has been observed for 4 keV He+ scattering from a Pt{111}-(1 x 1) surface. Atoms scattered on such semichannel planes are highly focused by the detailed structur al features of the surface and subsurface layers, giving rise to intri cate three-dimensional spatial patterns. These scattering patterns can be readily observed through the use of a time-and spatially-resolving microchannel plate detector using the technique of scattering and rec oiling imaging spectrometry (SARIS). Such three-dimensional scattering features are not normally observed in conventional ion scattering exp eriments using small-area detectors. Classical ion trajectory simulati ons using the scattering and recoiling imaging code (SARIC) are used t o simulate the scattering patterns and to provide an analysis of the s urface and subsurface layers involved in the scattering, the focusing of incoming and outgoing atom trajectories, and the role of thermal vi brations on the scattering patterns. The high sensitivity of the SARIS images to the details of the surface and subsurface atomic arrangemen ts advocate its potential as a surface structural analysis technique. (C) 1998 Elsevier Science B.V.