Scattering of 4 keV Ne+, Na+ and F+ ions from a NaCl (100) surface under asmall angle of incidence. Angular distributions and charge fractions

We have measured the angular polar distributions of the emitted particles ( positive ions, negative ions and neutrals) in the scattering of 4 keV F+, N e+ and Na+ from a NaCl (1 0 0) surface under an incidence angle of 2 degree s. According to the incident ion the angular distributions for ions are shi fted or not, enlarged or not, with respect to the neutral one, resulting in different charge fraction dependence. Depending on the electronic structur e of the projectile, charge exchange processes of different type are involv ed and allow us to understand the measured distributions. We have also reco rded the dependence of the charge fractions with the azimuthal angle of the incident projectile. Sensitive variations for low-indexed directions of th e crystal are correlated with specific trajectories of the projectile. (C) 2000 Elsevier Science B.V. All rights reserved.