Tuesday, 24 May 2005 - 1:40 PM

This presentation is part of: Surface and Interface Science II

First Principles Resonance Widths and Energies for Ions Scattering off Surfaces: Neutralization Predictions for Scattered Ions

Keith Niedfeldt1, P. Nordlander2, and Emily A. Carter1. (1) Princeton University, Princeton, NJ, (2) Rice University, Houston, TX

By combining a first principles periodic density functional theory calculation of adsorbate resonance widths and shifts with a many-body dynamical theory of charge transfer, we assess charge transfer rates for ions scattering off surfaces. This goes beyond previous approaches, which have been limited to modeling metal surfaces with either jellium potentials or finite clusters. Here we consider Li+ scattering from Si(001), Mg(0001), Cu(001), and Al(001) surfaces. For metals we show how the Li 2s orbital hybridizes with metal valence bands, near the surface, increasing the width of the 2s energy level. For Si(001), as expected the Li 2s orbital interacts most strongly with the dangling bonds in Si dimers. This in turn affects the charge transfer rates between the ion and the surface. Our predictions for scattering are in good agreement with the experimental neutralization fractions of scattered Li ions. These results show that lateral corrugation, neglected by the jellium approximation used in most previous calculations, should be accounted for in quantitative theories of ion-surface scattering.

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