2-ELECTRON AND 3-ELECTRON PROCESSES IN H-3(+)-HE COLLISIONS

We have measured the energy spectrum of electrons emitted at 160-degrees laboratory angle for 50-110 keV H-3+-He collisions. The spectra show the well-known autoionizing states of He, and the He-(1s2s2) Feshbach resonance. The triplet autoionizing states result from three-electron processes, whereas the singlets can be formed by either two- or three-electron processes. The Feshbach resonance is formed by a transfer and excitation mechanism, a two-electron process. The dependence of these states on the energy of the incoming beam is presented.