State-selective electron capture by state-prepared N2+ (P-2) ions in collisions with molecular hydrogen

The technique of double translational energy spectroscopy (DTES) has been used to study state-selective electron capture by pure beams of ground state N2+ 2S(2)2p(P-2) ions for the first time. The main collision channels have been identified and their relative importance assessed in measurements of one-electron capture by N2+ 2s(2)2p(P-2) ions in collisions with H-2 at energies of 1.75, 4, 6 and 8 keV. These new results help to resolve discrepancies and serious ambiguities in the interpretation of previous measurements carried out with N2+ beams containing unknown fractions of metastable ions.