Measurements of one-electron transfer between 3He2+ and H- ions

Measurements with inclined beams for one-electron transfer between 3He2+ and H- ions show that the cross section falls from 4.7*10-14 cm2 at 30 eV to 2.0*10-14 cm2 at 2600 eV. Systematic errors are assessed to be less than +or-8% and random errors are typically +or-5%. Results of a simple Landau-Zener calculation are also presented and these are in broad agreement with the measurements. Comparisons are also made between the present experimental results and measurements of the mutual neutralisation of H+/H-, He+/H- and H2+/H-. When these cross sections are plotted against the relative speed of the reactants they fall close to a common curve, but the results for 3He2+/H- are larger, due to the greater attraction of the doubly charged ion.