Transfer-excitation processes in collisions of N3+ ions with H2, He, Ne, and Ar targets

High-resolution translational energy-gain spectra for single-electron capture by N3+ ions from H2, He, Ne, and Ar have been measured experimentally at laboratory impact energies of 6, 9, 12, and 15 keV. For N3+-He and Ne collisions, transfer excitation into the 2s2p2 state of N2+ is significantly populated, while in N3+-H2 collisions, transfer excitation into the 2s2p22P state dominates at low energies. In N3+-Ar collisions, pure single-electron capture into 3s is selectively populated. In all the collision systems studied here, contributions from processes commencing with a long-lived metastable state of N3+(2s(2S)2p3P) are detected. The translational energy-gain spectra are interpreted qualitatively in terms of the reaction windows, which are calculated using the single-crossing Landau-Zener model and the extended version of the classical over-the-barrier model. Total cross sections for single-electron capture for N3+ ions colliding with He and H2 are also measured and compared with available measurements and theoretical calculations. copyright 1996 The American Physical Society