Charge state effects in the interaction of multiply charged ions with surfaces

The interaction Of multiply charged ions (MCI) with clean solid surfaces is discussed, with main emphasis on the ion-induced electron emission. At projectile impact energies close to the lower limit set by the projectile's image charge attraction, multiply excited ''hollow atoms'' are transiently formed and mainly decay under potential emission which strongly depends on the projectile's charge state. At sufficiently higher energies the electron emission is dominated by the projectile's kinetic energy. Charge state effects in kinetic electron emission are considerably weaker and therefore not so well understood as for PE, and respective experimental results show that they are much more pronounced for insulator than for metal targets To achieve a still better understanding Of potential and kinetic emission processes a new experimental setup has been designed, which permits coincidence measurements between emitted electrons and charge state analysed scattered projectiles. This setup will be described together with some preliminary results.