Multi-electron effects in fast ion collisions with Li atoms

We investigate target electron removal in O⁸⁺-Li and Li²⁺-Li collisions at 1500 keV/amu and 2290 keV/amu, respectively. In the former case, we present doubly-differential cross sections for inner-shell electron removal showing the importance of multi-electron effects. In the latter case, the singly-differential cross-section results indicate that in outer-shell ionization a single-electron process plays the dominant part. The K-shell ionization results suggest only weak contributions from multi-electron processes, but a large discrepancy between experimental and single-particle theoretical results indicates a more complex nature of the process. (paper)