Study on interactions of He atoms and ions with an Al(111) surface

He+ ions and He-0 atoms with keV energies are scattered under a grazing angle of incidence from an Al(111) surface. Fractions of surviving ions and energy gains of ions prior to neutralization are derived from charge state distributions for scattered projectiles and shifts of angular distributions for impact of charged and neutral projectiles. By comparing the experimental data,with theoretical predictions for the interaction potential, the neutralization rate, and the He ls level shift we reveal deficiencies of the present theoretical understanding for the interaction of He atoms and ions with Al(111), a "model system" for the study of atom-surface interactions. We demonstrate that our data is very sensitive on interaction potentials, the (Auger) neutralization rate, and the He ls level shift. Our work provides important experimental input for in-depth tests of theoretical models for the interaction of He atoms and ions with Al(111). (C) 2007 Elsevier B.V. All rights reserved.