THE INFLUENCE OF INNER-SHELL ELECTRON PROMOTION ON CHARGE-EXCHANGE PROCESSES IN LOW-ENERGY ION-SCATTERING FROM SURFACES

The influence of inner-shell electron promotion on charge exchange in low energy (1-7 keV) Ne+ ions scattered from the Cu (1 0 0), Ni (I 0 0 ) and Fe (1 1 0) surfaces has been studied systematically, The yield o f Ne+ ion scattered From these surfaces has been measured as a functio n of incident ion energy under various scattering geometries, The rela tive Ne+ ion fraction, which is proportional to the normalised ion yie ld divided by the differential scattering cross section, is studied an d an empirical formula for relative ion fraction has been extracted. T he formula combines the charge exchanges along the incoming trajectory , during the close encounter, and along the outgoing trajectory into o ne simple expression. It can be concluded that inner-shell electron ex citations during close encounters contribute significantly to the char ge exchange in the scattering systems studied in this work. (C) 1997 E lsevier Science B.V.