The mass and ion kinetic energy spectra of H 2 , HD and D 2

The collision-induced reactions, (1) H +· 2 → H + + H · , (2) H + 3 → H + + H 2 , and (3) H + 3 → H +· 2 + H · , and the corresponding reactions of the deuterated species, have been examined for their kinetic energy release using a double focusing mass spectrometer. Reaction (1) encompasses two discrete processes, the first apparently involving only the ground electronic state of H + 2 and the second apparently occurring via excitation to the repulsive first excited state. Isotope effects on the kinetic energy release associated with the transition to the repulsive state in process (1) are consistent with the proposed mechanism. Process (2) gives a ‘meta- ­ stable peak’ which shows fine structure, possibly due to individual vibrational states of H 2 . Reaction (3) occurs by electronic transition to a repulsive state(s).