Electron impact ionization of ground-state and metastable Li+ ions

Direct ionization of ground-state Li+(1s(2) S-1(0)) and metastable Li+(1s2s S-3(1)) ions by electron impact has been studied in the energy range from threshold to 1000 eV using state-of-the-art experimental and theoretical approaches. Absolute cross sections obtained by crossing a beam of Li+(1s(2)) ions with a beam of electrons and results of convergent close coupling (CCC) calculations agree within experimental error bars of approximately 10%. Mixed beams of Li+(1s(2)) and Li+(1s2s S-3) ions were also prepared and apparent cross sections were measured. Good agreement with CCC theory is obtained assuming suitable fractions of metastable ions in the parent beam.