Internal state distribution of N2H+ produced by hydrogen abstraction from H2 and by proton transfer of H3+

The reaction of N2+ (X,v = o) with H2 is interesting in that the product N2H+ rather than H2+ appears, though the charge transfer to give H2+ (X,v = o) is exoergic by 0.15 eV and a favorable Franck-Condon Factor exists for the H2 (X,v = o) → H2+ (X,v = o) transition (FCF approximately 0.087). Usually charge transfer takes over, when it competes with other reaction mechanisms. However an exception is the charge transfer between Ar+ and N2, where the exoergic channel into N2+ (X,v = o) does not appear at an appreciable rate at thermal and suprathermal energies. The inhibition of this exoergic transfer seems to occur due to nonexistent crossings between the Arsup+ - N2 and N2+ (X,v = o) - Ar potential curves. The same situation may in the case of the N2+ (X,v = o) reaction with H2 inhibit charge transfer, so that heavy particle transfer (hydrogen abstraction) occurs instead. For N2+ (X,v = 1) however a favorable curve crossing seems to allow for a fast charge transfer. (Author)