One-electron capture by slow doubly charged ions in h and H2

Cross sections for one-electron capture by Ba 2+ , Ti 2+ , Mg 2+ , Cd 2+ , Zn 2+ , Kr 2+ and B 2+ in both H and H 2 have been determined in the energy range 0.8-40 keV. A tungsten-tube furnace was used to provide a target of highly dissociated hydrogen. Cross sections in H for moderately exothermic processes, which involve pseudo-crossings of potential energy curves at moderate internuclear separations were found to be very large at low velocities. Cross sections for other processes decrease rapidly with decreasing velocity. No clear relationship between cross sections in H and those in H 2 is apparent. Measured cross sections are believed to pertain to ground-state primary ions.