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

The interaction of multiple charged ions (Mc) with clean solid surfaces is discussed, with main emphasis on the thereby induced electron emission. At projectile impact energies not far above the lower limit set by the projectile's image charge attraction, multiply excited 'hollow atoms' are transiently formed and then decay under potential emission which strongly depends on the projectiles' charge state. Only at considerably higher impact energy the electron emission becomes dominated by the projectile's kinetic energy. Charge state effects in kinetic electron emission are much less pronounced and therefore not so well investigated as for PE. However, respective experimental results show that they are more important for insulator than for metal targets. In order to achieve a still better understanding of such potential and kinetic emission processes a new experimental setup has been designed which permits coincident measurements between emitted electrons and charge state analysed scattered projectiles. This setup is described and some preliminary results achieved with its help are demonstrated. (author)