Electron impact ionization of Kr10+-Kr18+ ions

Cross-sections for single ionization of Kr10+-Kr18+ ions by electron impact are calculated in the Coulomb-Born approximation by the code 'ATOM' and compared with experimental data and with other theoretical results for charge states 10 and 18. Single electron impact ionization is sum of the contributions from direct ionization and from excitation of the autoionizing levels. Direct ionization includes ionization from 3s, 3p and 3d shells only since ionization from 1s, 2s, 2p results in double ionization. The autoionizing levels 2s 2p6 3s2 3p6 3dm nl and 2s2 2p5 3s2 3p6 3dm nl decay via autoionization and finally contribute to single ionization. The results are found to be in satisfactory agreement with experimental results obtained in a crossed electron-ion beam experiment. The case of ions formed in metastable states is studied for Kr18+ where it was observed in the experiments