VELOCITY DEPENDENCE OF THE K-AUGER DEEXCITATION OF O7+ PROJECTILES IMPINGING ON SOLID CU(111) AT 51 AND 102 KEV

The time evolution of deexcitation of O7+ ions penetrating the (111) s urface of Cu is studied by means of secondary electron spectroscopy. I t is found that the filling of the K shell proceeds faster at 102 keV than at 51-keV ion energy, by about 10%. This velocity dependence is d etermined from a comparison of emission depth profiles, assuming strai ght-line trajectories for the ions. No further model is needed for the ion deexcitation or the solid-state interactions of the emerging Auge r electrons. The model independence is based on three steps: (i) the e mission depth profiles for different ion energies nd angles are evalua ted only in conditions where they are practically equal; (ii) the full K Auger electron spectra with their inelastic parts are obtained usin g matching pairs of measurements with O6+ projectiles; and (iii) the o bservation angles are adjusted to equalize, for both ion energies, the laboratory energies of the Auger electrons at emission as well as the ir solid-state interactions on their way to the surface. The present m ethod can provide benchmark values for multistep cascade models of hig hly charged ion deexcitation in solids.