Relaxation of slow highly charged ions penetrating a solid surface - energy deposition and reemission

Highly charged ions carry a large amount of potential energy, which is defined as the sum of the binding energies of all removed electrons. In the case of low velocities of the ions this energy can exceed their kinetic energy.
Approaching the solid surface the ions are neutralized, relaxe to the ground state, and their potential energy is released. Thereby different mechanisms, such as surface sputtering, secondary ion emission, secondary electron emisson and X-ray emission take place [1]. The secondary particles leaving the surface carry only up to 10% of the potential energy.
Using a calorimetric setup [2] we measured the amount of the potential energy which remains in the solid to 85% +/- 10%.
To study the detailed mechanism of the energy retention materials with different electronic structures were investigated: Cu, n-Si, p-Si, SiO2.
We can conclude, that the difference in energy depositon between these materials is below 10%.
The calorimetric results are rounded off with results from energy reemission measurements using electron spectroscopy.
The value of the reemitted energy increases with increasing charge state up to 10%.
[1] A. Arnau et.al.: Surf. Sci. Rep.27, 113 (1997).
[2] U. Kentsch et.al.: Phys. Rev. Lett.87, 10 (2001).