Ionization and charge transfer in collisions of protons with Ba+ and Sr+ ions

Abstract

A fast intersecting beam technique previously developed in this laboratory has been used to study collisions of protons with the alkali-like ions Ba+ and Sr+ at CM energies within the range 50-500 keV. Absolute cross sections for Ba2+ and Sr2+ production from the combined processes of charge transfer and ionization have been measured. Separate measurements of the cross sections for charge transfer also allowed cross sections for ionization to be determined. Measured cross sections for charge transfer are shown to be in poor agreement with available theoretical predictions. Cross sections for ionization (believed to be dominated by excitation-autoionization) are compared with those for equivelocity electron impact and Born predictions. The applicability of a simple classical scaling relation is also considered.