INTERPLAY OF RESONANT AND AUGER PROCESSES IN PROTON NEUTRALIZATION AFTER GRAZING SURFACE SCATTERING

We present model calculations for proton neutralization after grazing reflection at an aluminum surface over a wide range of projectile velocities around the Bohr or Fermi velocity. The contribution of excited hydrogen states to the neutral fraction, as well as negative-ion formation can be regarded as small in this case. Both resonant and Auger electron capture from the metallic conduction band into the 1s ground state of hydrogen as well as electron loss by resonance and Auger ionization of the ground state are taken into account on equal footing within a rate-equation approach. As a consequence, our model allows to estimate, for the first time, the effect of the particle velocity parallel to the surface plane on the relative role of resonant and Auger-type electron transfer in ion-surface neutralization. The results of our theoretical model are compared with recent experimental data for grazing scattering of protons at an Al(111) surface.