Auger transitions and plasmon decay produced by hollow atoms at an Al(1 1 1) surface

Low-energy electron emission induced by 1–4 keV Ne4þ ion impact on an Al surface was analyzed. Distinct lines observed near 22 eV are attributed to Auger electrons ejected from doubly excited Ne decaying well above the surface. Spectral structures near 11 eV are primarily associated with the decay of bulk plasmons. After instrumental effort of extending the capability of the spectrometer to measure electrons with energies as low as 2 eV, we made observations of intense spectral structures near 6.5 eV, which are likely to be due to the decay of surface plasmons. Absolute electron yields were studied as a function of the incidence angle of the Ne4þ projectile and were interpreted by means of model calculations. 2002 Elsevier Science B.V. All rights reserved. PACS: 79.20.Rf; 29.20.Ap; 34.50.Dy