Double-electron capture and radiative stabilization processes in slow ion-atom collisions

Mechanisms for double-electron capture producing projectile doubly excited states in O6+ + He and Ne10+ + He collisions are studied. Emphasis is given to slow collisions with projectile energies of a few keV. At these impact energies the production of configurations nln'l' of nonequivalent electrons (n' much greater than n) is dominant. It is shown that the creation of nonequivalent electron states O4+(1s(2)2pn'l') and Ne8+(3ln'l') with n' greater than or equal to 6 originates from dielectronic processes involving electron-electron interaction. After the collision the populated excited states decay either by Auger electron emission or by radiative (photon) emission. Individual contributions to radiative stabilization of the Ne8+(nln'l') states (n = 3-4) are studied in the impact-energy range from 1-150 keV. The relative importance of the different contributions to stabilization changes significantly with varying collision energy. At 1 keV the major contribution is due to the decay of the configurations 3lnl' (n greater than or equal to 6) created by collisional dielectronic processes. (C) 1999 Elsevier Science B.V. All rights reserved.