Electron emission from below the surface induced by highly charged ions: Effect of depth distribution of electron excitation and ion transport on the emission properties

Abstract

Electron emission induced by the impact of highly charged ions on metal surfaces is due to different mechanisms. During the interaction of the ion with the metal surface, hollow atoms are formed above and below the surface. At low impact energies, autoionization processes in front of the surface mostly determine the emission properties. With increasing impact energy, excitation processes from below the surface gain in importance. When the hollow atom moves inside the metal, empty inner orbitals are successively filled by Auger transitions and collisional charge transfers. The filling dynamics of the hollow atom determines the strength of the excitation by Auger processes as well as the depth distribution of this excitation. The ion transport process in the first layers of the metal also influences this depth distribution. In this work, electron emission due to the release of K- and L-Auger electrons is calculated by Monte Carlo simulation for Ne9+ impact on Al. The transport of incident ions and of the excited electrons as well as the filling dynamics of the hollow atom are taken into account.