Investigations of the interactions of highest charge state ions with surfaces

Experimental results from a series of investigations, the aim of which is to provide an exploratory overview of the wide range of phenomenon associated with the interaction of slow very highly charged ions with solids and solid surfaces, are reported. Incident charge state dependencies of secondary electron, x-ray and secondary ion emission are measured. In addition, microscopic studies are performed using an "Atomic Force Microscope" to investigate highly charged ion induced surface defects. The ions, used for these studies, range from O 7+ to Th 80+ and U 82+ with low incident kinetic energies (~2 eV/amu to 3 keV/amu). As an overall result, enhancements for the low energy secondary electron, sputter ion and photon emission are observed with increasing charge states. X-ray emission spectra are found to be consistent with the formation of so called "hollow" atoms above and at the surface as part of the neutralization processes. Small angle scattering behaviour, under specular reflection conditions, indicate very fast decay processes for the hollow atom, outside the solid surface. The microscopic studies reveal interesting nano-size surface defects caused by single highly charged ion incidence.