In this project in the Physical Chemistry program of the Chemistry Division, Professor Kenneth C. Janda of the Department of Chemistry of the University of California at Irvine will pursue a series of investigations on the spectroscopy and dynamics of rare gas- halogen van der Waals compounds. Among these are the HeBr2 and NeBr2 systems. Not only are their structures to be investigated, but especially the potential energies of their weak interactions are to be determined. Spectroscopy at the highest possible resolution will be employed to obtain experimental data on the electronic states of Br2, and on HeBr2 , NeBr2 and ArBr2. Intramolecular vibrational energy redistribution dynamics in ArBr2 will be investigated. This work will be extended to complexes in which Br2 is imbedded in large He and Ne clusters. This research is of great importance for the understanding the interaction involving large halogen-containing molecular clusters. It provides bench mark data for the development of models for the structures and dynamics of weakly bonded molecular complexes.