Low-energy electron capture byNe2+ions from H(D)

Abstract

Using the Oak Ridge National Laboratory (ORNL) ion-atom merged-beams apparatus, the absolute, total single-electron-capture cross section has been measured for collisions of ${\mathrm{Ne}}^{2+}$ with deuterium (D) at center-of-mass (c.m.) collision energies of $59--949\phantom{\rule{0.3em}{0ex}}\mathrm{eV}∕\mathrm{u}$. With the high-velocity ion beams now available at the ORNL Multicharged Ion Research Facility, we have extended our previous merged-beams measurement to lower c.m. collision energies. The data are compared to all four previously published measurements for ${\mathrm{Ne}}^{2+}+\mathrm{H}(\mathrm{D})$ which differ considerably from one another at energies $\ensuremath{\lesssim}600\phantom{\rule{0.3em}{0ex}}\mathrm{eV}∕\mathrm{u}$. We are unaware of any published theoretical cross-section data for ${\mathrm{Ne}}^{2+}+\mathrm{H}(\mathrm{D})$ at the energies studied. Early quantal rate coefficient calculations for ${\mathrm{Ne}}^{2+}+\mathrm{H}$ at eV/u energies suggest a cross section many orders of magnitude below previous measurements of the cross section at $40\phantom{\rule{0.3em}{0ex}}\mathrm{eV}∕\mathrm{u}$ which is the lowest collision energy for which experimental results have been published. Here we compare our measurements to recent theoretical electron-capture results for ${\mathrm{He}}^{2+}+\mathrm{H}$. Both the experimental and theoretical results show a decreasing cross section with decreasing energy.