  Thin film metal-insulator-metal junctions are used in a novel approach to
investigate the dissipation of potential energy of multiply charged ions
impinging on a polycrystalline metal surface. The ion-metal interaction leads
to excited electrons and holes within the top layer. A substantial fraction of
these charge carriers is transported inwards and can be measured as an internal
current in the thin film tunnel junction. In Ag-AlOX-Al junctions, yields of
typically 0.1-1 electrons per impinging ion are detected in the bottom Al
layer. The separate effects of potential and kinetic energy on the tunneling
yield are investigated by varying the charges state of the Ar projectile ions
from 2+ to 9+ for kinetic energies in the range from 1 to 12 keV. The tunneling
yield is found to scale linearly with the potential energy of the projectile.
