Abstract
We have recorded the O-atom velocity map photofragment ion images resulting from the photodissociation of O2-pyrrole and O2-pyridine clusters near 226 nm. To record the images, the O-atom photoproduct was state-selectively ionized and projected onto a two-dimensional (2D) position-sensitive detector. The resulting ion images from the clusters show evidence for three dissociation pathways. In the images from either cluster, we observe an isotropic process with kinetic energy near the one-photon limit, which is due to dissociation of the cluster into molecular subunits followed by secondary dissociation of molecular oxygen. Both O2-pyrrole and O2-pyridine also show a low kinetic energy process that appears to be isotropic in nature. This low kinetic energy process likely results from dissociation of the cluster resulting in significant internal energy in the organic fragment followed by secondary dissociation of O2. Finally, our ion images for O2-pyrrole show O atoms resulting from a two-photon dissociation channel, which has been previously attributed to the formation and subsequent photodissociation of excited O2 (a 1Îg). At similar laser intensities, O2-pyridine does not show significant dissociation through the channel producing O2 (a 1Îg); however, this channel shows a laser intensity dependence for O2-pyridine.