DOUBLE 2P ELECTRON-EXCITATION IN LOW-ENERGY NE- AN ENERGY-LOSS STUDY(SINGLE SCATTERING FROM A SI SURFACE )

Results of 1950 eV Ne+ single scattering from a Si surface show that a ll the backscattered Nei ions have suffered severe inelastic energy lo ss and the total inelasticity in the close binary encounter amounts to 45+/-4 eV. This value is well beyond that required for one-electron e xcitation 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 aw ay from the surface is the main mechanism for Ne+ scattered from Si. ( C) 1997 Elsevier Science B.V.