Doppler-free kinetic energy release spectrum of N-2(2+)

A Doppler-free kinetic energy release spectrum of N-2(2+) has been recorded using a coincident time-of-flight technique, resolving vibrational structure in the optically active A (1) Pi(u), D (3) Pi(g) and D (1) Sigma(u)(+) electronic states. A comparison is made with earlier photofragment and optical measurements. The upsilon = 7-10 levels of the A (1) Pi(u) state, dissociating into the lowest atomic level N+(P-3) + N+(P-3), are observed in the spectrum. The lifetime of the upsilon = 7 level was determined to 300 +/- 100 ns while the absence of lower levels indicates lifetimes above 3 mu s. The D (3) Pi(g) state was found to support only two vibrational levels, dissociating into N+(P-3) + N+(P-3). The observed levels of the A (1) Pi(u) and D (3) Pi(g) states may dissociate either via tunnelling through the potential barriers separating the levels from the dissociation continuum or via electronic predissociation. Experimental data of the D (1) Sigma(u)(+) state indicate that optical transitions into the X (1) Sigma(g)(+) state dominate the decay of the upsilon = 0 level, while electronic predissociation dominates the decay of higher levels. For the upsilon = 0 and 1 levels of the D (1) Sigma(u)(+) state predissociation is observed into the N+(P-3) + N+(P-3), and the N+(P-3) + N+(D-1) ionic states, while predissociation into the N+(P-3) + N+(D-1) states is observed for the upsilon = 2 and 3 levels.