One-electron capture in collisions of 6 - 100 keV protons with oxygen atoms

Abstract

A crossed-beam technique incorporating time-of-flight analysis and coincidence counting of the collision products has been used to study one-electron capture by 6 - 100 keV protons in collisions with oxygen atoms. In these measurements, ground-state oxygen atoms were provided by an iridium tube furnace dissociation source. The measurements extend the energy range of previous experiments and, for the first time, provide separate cross sections for the simple charge transfer process (which is dominated by accidentally resonant one-electron capture) and for the transfer ionization process leading to formation. The present cross sections were obtained using a technique and normalization procedure different from all previous measurements. In particular, our measured values of are in good accord with previous 0.04 - 10 keV data by Stebbings et al based on a modulated crossed-beam technique but at variance with the considerably smaller values in the range 2.5 - 25 keV obtained by Williams et al using a furnace target method. While our values of decrease with increasing energy over the range considered, transfer ionization cross sections pass through a peak value at 34 keV where this process accounts for about 9% of the total one-electron capture cross section rising to 17.5% at 100 keV.