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Cross sections for the dissociative recombination of electrons and H2 + ions having low internal energies have been measured by means of the merged electron-ion beam technique. Narrow resonances associated with indirect capture into high-lying Rydberg states of the neutral molecule have been found. The use of ions with only two vibrational states significantly populated has allowed the high-resolution capability of the merged-beam technique to be clearly demonstrated.

This paper reports an measurements of the cross section for transfer ionization in He'+-Hcollisions over the barycentric energy range 0.16-1300 eV. The experimental method involves merged beams and coincident detection of the reaction products. The dependence of the cross section on the energy is rather similar to that of the one-electron exchange, suggesting that a two-step mechanism dominates the process.

The energy imparted to the ions in the transfer ionization reaction He2++H- to He++H++e has been measured in a merged beam experiment using two different techniques (magnetic analysis and time-of-flight). The result obtained in both cases is of the order of 6 eV and confirms that the transfer ionization proceeds in two steps: a single electron transfer at large internuclear separation followed by a resonant Penning ionization at small distances. With this view, a simple calculation of the cross section is presented, with results that are in good agreement with the available experimental data.