Measurements of Electron Capture in CloseH+-on-He andHe+-on-H Collisions

Abstract

Differential measurements of electron capture probability $P_0$ are made for close encounters in the reaction ${\mathrm{H}}^{+}$+He→H+${\mathrm{He}}^{+}$. The energy range of the incident proton is 1.6 to 180.0 keV and the scattering angle is varied from ½ to 4°. The impact parameters associated with these collisions extend from 0.015 to about 0.50 Å. There is little angular dependence to the data. When $P_0$ is plotted versus energy, a damped resonant structure is seen with peaks at 36, 7, and 2.6 keV with amplitudes of 0.52, 0.16, and 0.05, respectively. The phenomena are discussed in terms of the energy-level diagram for He${\mathrm{H}}^{+}$ and with reference to the existing theories for charge transfer in the nonresonant case. Measurements of the inverse reaction, ${\mathrm{He}}^{+}$ ions incident on atomic hydrogen targets, are also presented and discussed.