N(4S0), N(2D0), AND N(2P0) YIELDS IN PREDISSOCIATION OF EXCITED SINGLET-STATES OF N2

Predissociation in several singlet valence and Rydberg states of molec ular nitrogen has been investigated using photofragment spectroscopy. We report here measurements of the yields of the atomic fragment produ cts N(S-4(0)), N(2D0), and N(P-2(0)) from predissociation of specific rotational levels in the b' 1SIGMA(u)+ (v = 9-13), c 1SIGMA(u)+ (v = 3 ,4), c 1PI(u) (v = 3,4), and o 1PI(u) (v = 3) states of N2. These stat es are prepared by laser excitation from the metastable a'' 1SIGMA(g) + (v = 0) level in a fast (3 keV) molecular beam. Correlated atomic fr agments from single molecular dissociation events are monitored using. a position- and time-sensitive detector to obtain a complete and sens itive scheme for all possible N2 dissociation products. Dissociation o f the N2 states is found to occur to N(2D0) + N(S-4(0)), and N(P-2(0)) + N(S-4(0)) products; production of N(S-4(0)) + N(S-4(0)) is found no t to occur from any of the states investigated here. Branching of the dissociation products between the two active limits is found to be str ongly correlated with the energy of the predissociating level: levels lying < 112 200 cm-1 above N2 X 1SIGMA(g) + (v = 0) predissociate prim arily to the N(2D0) + N(S-4(0)) limit, while states above this energy primarily predissociate to N(P-2(0)) + N(S-4(0)). This behavior is dis cussed in terms of the potential energy structure of the triplet state s of nitrogen that lead to predissociation.