Charge dependence of electron capture and excitation cross sections in collisions of protons with closed-shellNa20+qq+clusters

Abstract

We have evaluated electron capture and excitation cross sections in collisions of ${\mathrm{H}}^{+}$ with isoelectronic ${\mathrm{Na}}_{20+q}^{q+}$ clusters $(q=\ensuremath{-}1,0,+1)$ in the impact energy range 40\char21{}500 eV. The theoretical method includes the many-electron aspect of the problem and makes use of realistic cluster potentials obtained with density-functional theory and a spherical jellium model. As expected, electron capture decreases monotonically with cluster charge, but the corresponding mechanism does not follow a common pattern. Excitation cross sections are very similar in the three cases investigated here.