2- AND 3-BODY EFFECTS IN SINGLE IONIZATION OF LI BY 95MEV U AR18+ IONS - ANALOGIES WITH PHOTOIONIZATION/

Cross sections for single electron emission have been measured in coll isions of 95 MeV/u Ar18+ with atomic Li for electron energies 5-1000 e V and angles 25 degrees-155 degrees. The high projectile velocity made possible the separation of two- and three-body processes in the angul ar distributions of the ejected electrons. Low-energy emission of the 2s electrons is found to be significantly influenced by two-body effec ts and, furthermore, the node in the Li 2s wave function manifests its elf in the angular spectra. Emission of 1s electrons is attributed mai nly to three-body effects. The two- and three-body processes are assoc iated with Compton scattering and photoabsorption, respectively.