ELECTRON-ELECTRON INTERACTIONS IN 2-ELECTRON PHENOMENA IN COLLISIONS OF FAST IONS WITH HE ATOMS

Recent experiments and calculations have helped to clarify the role of electron-electron interactions in two-electron phenomena in fast ion-atom collisions. The goal of this work has been to find and explore collision systems where the independent electron approximation (IEA) does not model the data well. Deviations from the IEA predictions are often described as effects due to electron correlations. This paper reviews recent studies of double ionization, transfer ionization, excitation ionization, and double excitation following collisions of fast ions with He atoms. Clear indications of electron-electron interactions have been observed in each of these phenomena. The experimental and theoretical results will be compared with emphasis on the conceptual models of electron correlation.