Hollow nitrogen atoms probing the jellium edge in front of a Au(111) surface

The deexcitation of slow, hydrogenlike nitrogen ions through interaction with a Au(111) surface is studied by $\mathrm{KLL}$ Auger electron spectroscopy. Special emphasis is given to processes occurring above the first atomic layer in projectiles that graze the electron gas at different depth. It is found that the increasing electron density around the jellium edge causes acceleration of $L$-shell filling. No difference is seen for projectiles that do or do not penetrate the first atomic layer. A cascade model of hollow atom deexcitation at the border of the electron gas is presented. The model includes a depth dependence of the $L$ shell filling rate caused either by interaction with the electron continuum or by a violent collision with a single target atom. Good agreement with experiment is found, along with some evidence for transfer of electrons from states below the Fermi level.