This award will support collaborative research between Robert Bernheim, Pennsylvania State University, and Paola Bicchi, University of Siena, Italy. This project is directed toward three areas of molecular and laser spectroscopy that have evolved out of previous contacts with scientists from Pisa, Siena, and Florence. The objectives of the research collaboration are threefold: laser- induced shifts in chemical equilibrium; molecular spectroscopy of vapors of the Group III Elements: Ga, In, Tl; and cooperative fluorescence studies of translational recoil of photodissociation products. The equilibrium shift studies are of fundamental importance as they provide unambiguous evidence for the use of lasers to "guide" chemical reactions. The collaboration will seek to extend this remarkable effect to chemical systems other than alkali metal vapors, possibly even to a stabilized vapor of H-atoms. The proposed studies of molecules such as In2 will reveal the potential of these systems for active gain media for visible and uv eximer lasers. Cooperative fluorescence studies will provide an alternative method for the investigation of translational energy partitioning resulting from photodissociation processes. The major benefit of the collaboration is the sharing of equipment -- a Bomem Fourier transform spectrometer at Penn State; a tunable mode-locked laser system and proper detection apparatus for quantum beat experiments in Florence; and tunable, pulsed and CW dye lasers in all locations where researchers with special skills and expertise make use of special variations. One of the major benefits of this work will be the stimulation of international activity in the field of laser-guided chemistry. Furthermore, the cooperative fluorescence method is a powerful, but unused, tool for studies of molecular dynamics.
