Electron impact ionization of Kr XI-Kr XIX ions

Beigman, I [Lebedev Physical Institute] Defrance, Pierre [UCL] Vainshtein, L [Lebedev Physical Institute]

Cross sections for the single ionization of Kr XI-XIX ions by electron impact are calculated in the Coulomb-Born approximation by the code 'ATOM' and compared with experimental data and other theoretical results for Kr XI, Kr XII and Kr XIX. Single electron impact ionization is the sum of the contributions from direct ionization and from excitation of the autoionizing levels. The first part includes only ionization from the 3s, 3p and 3d shells since ionization from the 1s, 2s, 2p shells results in double ionization. The autoionizing levels (1s(2)2s2p(6)3s(2)3p(6)3d(m)nl and 1s(2)2s(2)2p(5)3s(2)3p(6)3d(m)nl) decay via autoionization and finally contribute to single ionization. The results are found to be in satisfactory agreement with the experimental results obtained in a crossed electron-ion beam experiment in the energy range from threshold to about 6 keV. The case of ions formed in metastable states is studied as they were observed experimentally.