Towards a unified model for the formation of sputtered excited states

The statistical model for the formation of sputtered excited states is most convincingly tested by comparing experiment with theory for an ensemble of yields such as SiI, SiII, and SiIII, where the internal energies span a sufficiently wide interval. The electron-exchange model was previously tested by Veje in work where group II metals were bombarded in ultrahigh vacuum and the yields of excited ions were found to be unusually high relative to excited neutrals. It is argued that, with certain reservations, the two models may constitute limiting aspects of a single model which are valid, respectively, when electron exchange is forbidden or allowed. (Auth.)