Charge state analysis of heavy ions after penetration of uncleaned and sputter cleaned conducting surfaces

The evolution of the charge state distribution of fast ions inside a solid is of basic interest in various research fields as stopping power measurements etc. The existing models for the charge state evolution differ in the treatment of the projectile-exit-surface interaction, which has a strong influence on the final charge state distributions. We measured the charge state distributions for C+, N+, and O+ (30 ≤ E/M ≤ 130 keVu) impact on thin C, Cu, and Au foils, where the surface properties were modified by sputter cleaning. The measurements show a pronounced change of the mean projectile charge state to lower values in the case of sputter cleaned surfaces. This result underlines the importance of the projectile-surface interaction for the generation of the outcoming charge state distribution.