High-resolution translational energy spectra (0.2 eV at full width at
half maximum) have been obtained for single-electron capture by 4-keV
N2+ ions in collision with He, Ne, and Ar. Seven capture channels have
been unambiguously identified for each of the He and Ne spectra, many
of which have not been previously reported. This allows clarification
of earlier studies. Twelve reaction channels have been identified for
capture by N2+ in Ar, three of which involve excitation of the target
product Ar+ ion. All the observed channels are spin conservative. Com
peting channels which violate spin conservation are seen to be rigorou
sly suppressed.