Electron loss from fast partially stripped C and O ions incident on crystal targets

We have measured energy spectra of electrons emitted in a backward direction of Si and Ge crystals while bombarded by 2.5 and 3.5 MeV/u C 4+, C 6+, O 5+ and O 8+. Under 〈1 1 0〉 channeling incidence conditions, the loss electron yield from the partially stripped ions is appreciably reduced (by a factor of 0.5–0.6 for C 4+) relative to the non-channeling case. This reduction can be directly related to the reduced charge states of the channeled ions in the crystals. Furthermore, the evolution of the pre-equilibrium charge states of the incident ions has been deduced from a comparison of the effective nuclear charges for the loss electron yield, the low-energy electron yield, and the binary-encounter electron yield reported previously.