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 non equivalent electron states O4+(1s(2)2pn'l') and Ne8+(3ln'l') with n' greate r than or equal to 6 originates from dielectronic processes involving elect ron-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') sta tes (n = 3-4) are studied in the impact-energy range from 1-150 keV. The re lative importance of the different contributions to stabilization changes s ignificantly with varying collision energy. At 1 keV the major contribution is due to the decay of the configurations 3lnl' (n greater than or equal t o 6) created by collisional dielectronic processes. (C) 1999 Elsevier Scien ce B.V. All rights reserved.