Inelastic energy loss and inner-shell electron promotion in low energy Ne ions scattered from Fe and Ni surfaces

Abstract

Inelastic energy loss and inner-shell electron promotion of Ne + ions scattered from Fe(110) and Ni(100) surfaces have been studied systematically in the energy range from 1 to 7 keV at large scattering angles. The inelastic energy loss shows a threshold-type greater increase with incident energy in both scattering systems. Similar threshold-type behaviour is also observed in the scattered Ne + ion yield, the scattered Ne ++ ion yield and the peak fwhm. The threshold incident energy for such phenomena is found to increase with the atomic number Z of the target. It is suggested that excitations of the Ne 2s electrons occur during the close collision of the Ne with Fe or Ni atoms, resulting in a sudden increase in the inelastic energy loss. The excitation probability is found to depend on the atom position of the target relative to the swapping points of the Ne inner-shell energy levels. The ionization of the doubly excited Ne∗∗ particles alters the charge exchange behaviour of the Ne projectiles on their outgoing trajectories, leading to a remarkable increase in the scattered ion yield. The results show that inner-shell electron excitations could be significant in low energy ion surface scattering and may play an important role in the charge exchange process.