Spectroscopy and Dynamics of Weakly-Bound Complexes

Figure 12. Toluene - Noble Gas Complex Photodissociation

Figure 13. Toluene - noble gas complex versus bare toluene fluorescence

We use a variety of laser spectroscopic techniques to investigate weakly-bound clusters in the collision free environment of a molecular beam. In particular we are interested in excited state dynamics and fragmentation processes within the cluster. One ultimate aim is to be able to use the restricted geometries within clusters to pre-orient molecules prior to reaction.

Recently we have also begun focussing on the relaxation dynamics within the nascent photofragments following a photo-induced dissociation process. Figure 12 schematically shows one such process, as observed for rare gas - toluene complexes, whereby photoexcitation to specific vibronic levels in the the parent results in intermolecular vibrational relaxation (IVR) to a dissociative mode involving the van der Waals bound rare gas atom.

Monitoring the fluorescence and comparing with that of the bare toluene molecule provides a means of assessing the composition of the molecular beam. Figure 13 shows a comparison of the dispersed fluorescence spectra of Ar-Toluene and bare toluene.