Dynamical image charge effects on convoy electron emission from solid surfaces

We analyze surface effects on the spectrum of convoy electrons emitted from solids in close association with fast highly charged ions. Three competing mechanisms have been identified: Deceleration by the surface barrier, acceleration by the repulsive dynamical image force, and energy loss due to surface plasmon generation. The resulting energy shift is significantly reduced compared to the value for the barrier height for a jellium surface. We also give estimates for the probability for non-adiabatic transitions between bound states due to the sudden perturbation by the potential step upon exit