ELECTRON-IMPACT IONIZATION OF KRYPTON IONS (Q=8-13)

Absolute cross sections for electron impact single ionization of Kr10 and Kr11+ ions and double ionization of Kr-q+ (q = 8-13) have been me asured in an animated crossed-electron ion beam experiment. Ionization thresholds corresponding to particular electron pairs and inner-shell electron ejection are estimated from a structure Hartree-Fock calcula tion. For double ionization, results show that, along the homonuclear sequence, direct double ionization is progressively overcome due to th e increasing relative importance of direct L-shell ionization followed by autoionization. The presence of ions in metastable states is obser ved for Kr8+ and Kr9+ contributing to direct and indirect processes.