Experimental and theoretical study of electron-impact ionization of atomicions in the Sm isonuclear sequence - art. no. 052706

Experimental measurements and theoretical calculations of absolute cross se ctions are carried out for the electron-impact ionization of atomic ions in the Sm rare-earth-metal isonuclear sequence. Absolute cross sections for S Mq+ ions for q = 1 - 12 were measured using the electron-ion crossed-beam t echnique and calculated with the configuration-average distorted-wave metho d for the charge states q = 4-12. The theory includes both direct ionizatio n and excitation-autoionization contributions, and includes transitions fro m both ground and metastable levels. We present the cross sections in an el ectron-impact energy range from threshold up to 1000eV for all Sm ions up t o Sm12+. These systems are extremally complex, but the configuration-averag e method, when combined with statistical averaging of the cross sections ov er the many levels, provides results that are in overall good agreement wit h the experimental measurements. The single-ionization cross sections are d ominated by contributions from indirect mechanisms of excitation-autoioniza tion in the low-energy region.