Merging beams studies of Na, K, and Mg collisions with atmospheric ions

Ion-molecule reactions between Na, K, and Mg and some atmospheric molecular ions have been studied at relative energies between 0.05 and 10 eV using a merging beams apparatus. In all cases the exothermic reactions proceed via stripping mechanisms and the endothermic reactions proceed via rebound mechanisms. The absolute cross sections for some of the reactions have been measured. It was possible to determine D°0 (Na+−O) = 0.8 ± 0.3 eV and D°0 (K+ − O) = 0.3 ± 0.3 eV from the energy dependence of the cross sections for the reactions of Na and K with CO+. Some details of the merging beams technique are discussed.