Double 2p electron excitation in low-energy Ne+ single scattering from a Si surface: an energy loss study

Results of 1950 eV Ne+ single scattering from a Si surface show that all the backscattered Nei ions have suffered severe inelastic energy loss and the total inelasticity in the close binary encounter amounts to 45+/-4 eV. This value is well beyond that required for one-electron excitation from the neutralized Ne-o, but agrees well with that for the double 2p electron excitation of a neutralized Ne to 2p(4)(D-1)3s(2). These findings contrast the re-ionization model proposed by Souda et al. [Phys. Rev. Lett. 75 (1995) 3552; Surf. Sci. 363 (1996) 139], and confirm that the formation of autoionization states which decay far away from the surface is the main mechanism for Ne+ scattered from Si. (C) 1997 Elsevier Science B.V.