Abstract
Our primary goal was to measure the NO (A) photoproduct appearance energy and ground-state dissociation energy of the N2-NO complex. We recorded velocity map ion images of NO photofragments resulting from the dissociation of the N2-NO complex excited between ∼225.8 and 224.0 nm, which ranged from the photodissociation threshold to about 342 cm-1 above the threshold. In the experiment, one photon dissociated the complex through the N2 (X 1ςg+)-NO (A 2ς+) N2 (X 1ςg+)-NO (X 2) transition, and a second photon nonresonantly ionized the NO (A) photoproduct. The lowest-energy photons near 225.8 nm did not have sufficient energy to photodissociate the lowest excited state of the complex; however, dissociation was observed with increasing photon energy. On the basis of the experiments, we determined the appearance energy for the NO (A) photoproduct to be 44 284.7 ± 2.8 cm-1. From the appearance energy and the NO A X origin band transition, we determined a ground-state dissociation energy of 85.8 ± 2.8 cm-1. As we increased the photon energy, the excess energy was partitioned into rotational modes of the diatomic products as well as product translational energy. We found good agreement between the average fraction of rotational energy and the predictions of a simple pseudo three atom impulsive model. Finally, at all photon energies, we observed some contribution from internally excited complexes in the resulting P(ET). The maximum internal energy of these complexes was consistent with the ground-state dissociation energy.