Crystal effects in the neutralization of He+ ions in the low energy ion scattering regime.
Investigating possible crystal effects in ion scattering from elemental surfaces, measurements of the positive ion fraction P+ are reported for He+ ions scattered from single and polycrystalline Cu surfaces. In the Auger neutralization regime, the ion yield is determined by scattering from the outermost atomic layer. For Cu(110) P+ exceeds that for polycrystalline Cu by up to a factor of 2.5, thus exhibiting a strong crystal effect. It is much less pronounced at higher energies, i.e., in the reionization regime. However, there a completely different angular dependence of the ion yield is observed for poly- and single crystals, due to massive subsurface contributions in nonchanneling directions.
Institut für Experimentalphysik, Johannes Kepler Universität Linz, A-4040 Linz, Austria.
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Primetzhofer
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Markin
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Juaristi
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Taglauer
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Bauer