PHOTODISSOCIATION OF N-LESS-THAN-OR-EQUAL-TO-N-LESS-THAN-OR-EQUAL-TO-7) - BRANCHING RATIOS FOR FORMATION OF N2+ AND N4+, AND N2+ FRAGMENT VIBRATIONAL-EXCITATION( CLUSTERS (2)

Dynamical processes accompanying the photofragmentation of (N2)n+ clus ters (n = 3-6) have been investigated. Branching ratios for the format ion of N2+ and N4+ photoproducts have been determined at wavelengths s panning the continuous absorption of the chromophore N4+ (630, 532, 39 6, 315, and 266 nm). In addition, the fraction of N2+ photofragments i n excited vibrational states has been found using the monitor gas tech nique, whereby vibrationally excited N2+ molecules readily exchange ch arge with Ar buffer gas, and molecules in the v = 0 state do not. For a given sized cluster, as the photon energy increases, there is a tren d towards a larger proportion of N2+ compared to N4+ fragments and a m ild increase in the fraction of vibrationally excited N2+ fragments. O n the other hand, as the size of the primary cluster grows, there is a growth in the proportion of N4+ fragments and a decrease in the fract ion of vibrationally excited N2+ fragments. These features of (N2)n+ c luster photodissociation are argued to be consistent with primary abso rption by a N4+ chromophore core to form energetic N2+ and N2 fragment s followed by efficient intracluster recombination, exchange of charge , and exchange of vibrational quanta. The efficiency of these processe s for (N2)3+ and (N2)4+ suggest that in these species the N2 ligand(s) is (are) positioned at the end(s) of the linear N4+ ion core.