ELECTRON-IMPACT DOUBLE-IONIZATION OF BA AND BA(+)

Electron impact double ionization cross-sections for Ba and Ba+ have b een calculated in the binary encounter approximation. Hartree-Fock vel ocity distribution has been used for the first ejected electron and a hydrogenic velocity distribution for the second. For Ba+ the focusing effects of the target ion on the incident electron have been incorpora ted in the calculations. Contributions from ionization-autoionization to the ionization cross-sections, as observed in experiments, have bee n included in the present work. The calculated results show structures as observed in recent experiments.