Electron-capture processes of low-energy Si3+, Si4+, and Si5+ ions in collisions with helium atoms - art. no. 062701

Single- and double-electron-capture cross sections for Siq+ (g=3, 4, and 5) ions in collisions with He atoms have been measured at collision energies of a few hundred to a few thousand eV. The observed cross sections For sing le-electron capture are found to be of the order of 10(-15) cm(2), relative ly independent of the collision energy, and are generally in agreement with recent quantal calculations for Si3+ and Si4+ ions and with the present La ndau-Zener calculations for Si5+ ions. It is found that the measured cross sections for double-electron-capture processes, for which calculations are available only for Si4+ ions, are roughly one order of magnitude smaller th an those for single-electron capture and tend to increase as the collision energy increases.