INELASTIC ENERGY-LOSS AND INNER-SHELL ELECTRON PROMOTION IN LOW-ENERGY NE IONS SCATTERED FROM FE AND NI SURFACES

Inelastic energy loss and inner-shell electron promotion of Ne+ ions s cattered from Fe(110) and Ni(100) surfaces have been studied systemati cally 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 be haviour is also observed in the scattered Ne+ ion yield, the scattered Ne++ ion yield and the peak fwhm. The threshold incident energy for s uch phenomena is found to increase with the atomic number Z of the tar get. It is suggested that excitations of the Ne 2s electrons occur dur ing the close collision of the Ne with Fe or Ni atoms, resulting in a sudden increase in the inelastic energy loss. The excitation probabili ty is found to depend on the atom position of the target relative to t he swapping points of the Ne inner-shell energy levels. The ionization of the doubly excited Ne* particles alters the charge exchange behav iour of the Ne projectiles on their outgoing trajectories, leading to a remarkable increase in the scattered ion yield. The results show tha t inner-shell electron excitations could be significant in low energy ion surface scattering and may play an important role in the charge ex change process.