Charge transfer and electron emission in ion-surface interactions

The formation and decay of multiply excited projectiles during collisions o f slow highly charged ions with metal and insulator surfaces have been simu lated based on a classical over-barrier model. Simulations including the fu ll trajectory of the projectile have recently allowed the simultaneous eval uation of projectile kinetic energy gains, final charge-state distributions and emitted Auger electron yields in reasonable agreement with experiments . Due to the many-electron nature of these interactions, no detailed quantu m mechanical calculations are available. In contrast, for low charge states of the incident ion, quantum mechanical close-coupling calculations have b een performed that provide detailed information on resonance formation, hyb ridization, and electron transfer, including the effects of external electr ic fields. In this paper, some aspects of ion-surface collisions are review ed within both (many-electron) over-barrier models and quantum mechanical s ingle-electron expansion methods. (C) 1999 Elsevier Science B.V. All rights reserved.