Electron Emission from Insulators Irradiated by Slow Highly Charged Ions

Total electron emission yields have been measured for the first time resulting from impact of slow highly charged Arq+ (q ≤ 17), Xeq+ (q ≤ 50) and Hgq+ (q ≤ 68) ions on clean insulating LiF(001) and CaF2(111) surfaces at various impact angles. The surprisingly large yields show that even for the highest projectile charge states, a local charge-up of the surface poses no barrier for electron emission. We demonstrate that this is due to a strong sub-surface contribution in the potential electron emission process which is considerably more efficient in insulators because of the increased inelastic mean free path and the production of secondary electrons. [DOI: 10.1380/ejssnt.2008.54]