Dr. James M. Farrar, University of Rochester, is supported by a grant from the Experimental Physical Chemistry Program to study the photodissociation and fragmentation of gas phase solvated metal cations. The examples to be studied involve alkaline earth metal ions solvated by either water, ammonia or methanol. From studies of cluster ions of this type, which are produced under very high vacuum molecular beam conditions, much fundamental information can be obtained regarding the nature of ion molecule interactions in condensed phase environments. In these very elegant experiments, the cluster ions are produced by injection of low energy metal ions into a supersonic flow of solvent molecules from a pulsed nozzle source. Following mass selection, the cluster ions are dissociated by light from a tunable pulsed dye laser, and the daughter ions are mass analyzed as a function of the laser wavelength. Optical absorption spectra and product mass spectra are used to elucidate structural and dynamical properties of the solvated metal cations. Specific issues to be investigated during the course of this research involve: 1) changes in the absorption spectrum as a function of cluster size, 2) evaporation of solvent molecules as an energy dissipation mechanism, and 3) the possibility of intramolecular electron transfer in large clusters. The experiments will be performed using a tandem time of flight mass spectrometer which will be constructed during the term of the grant.
