STATE-SELECTIVE ELECTRON-CAPTURE BY STATE-PREPARED N2-2) IONS IN COLLISIONS WITH MOLECULAR-HYDROGEN( (P)

The technique of double translational energy spectroscopy (DTES) has b een used to study state-selective electron capture by pure beams of gr ound state N2+ 2S(2)2p(P-2) ions for the first time. The main collisio n channels have been identified and their relative importance assessed in measurements of one-electron capture by N2+ 2s(2)2p(P-2) ions in c ollisions with H-2 at energies of 1.75, 4, 6 and 8 keV. These new resu lts help to resolve discrepancies and serious ambiguities in the inter pretation of previous measurements carried out with N2+ beams containi ng unknown fractions of metastable ions.