Electron spectra resulting from autoionization in low-energy Li(+) + He collisions

Abstract

Spectra of electrons ejected from doubly excited states of helium have been extensively measured at several observation angles for impact of lithium ions at energies lower than 5 keV. ''Molecular-autoionization'' spectra have been found at forward observation angles, and analyzed in terms of the Gerber-Niehaus theory with modification. The spectral shapes of atomic-autoionization peaks have been discussed in relation to both the Barker-Berry effect and the Doppler effect. Excitation cross sections of autoionizing states have been determined by a new method that uses simultaneous impact of ions and electrons.