Neutralization of highly charged ions at grazing incidence on a metal surface

Electron energy spectra and total electron yields are studied to provide information on the neutralization of 24-keV ${\mathrm{N}}^{\mathit{q}+}$ ions (q=2,4,6) incident at grazing angles on a Cu(100) surface. A computer simulation of the neutralization is presented that assumes resonant neutralization of the ions leading to highly excited ‘‘hollow’’ atoms. Deexcitation of these atoms is assumed to take place by purely intra-atomic Auger transitions. The results of this simulation are not in agreement with our experimental observations. A modified simulation, assuming again resonant neutralization of the ions followed by faster deexcitation processes, and, in addition, fast Auger deexcitation directly into the L shell, shows a much better agreement with the experimental observations.