US-Netherlands Cooperative Research On Ultra High-ResolutionLaser Spectroscopy in Molecular Beams: The Transition from Order to Chaos.

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This award supports Professor David W. Pratt of the University of Pittsburgh to pursue research collaboratively with Dr. W. L. Meerts of the Physics Department of the Catholic University of Nijmegen. They are carrying out ultra high-resolution laser experiments to examine a variety of dynamical phenomena occurring in the electronically excited states of large molecules, including benzophenone, napthalene, quinoline, pyrimidine, pyrazine, methyl salicylate and several organic molecule/rare gas solvent clusters. The phenomena under study include intramolecular vibrational relaxation, internal conversion, intersystem crossing, cluster formation, and chemical reactions. Their experiments will utilize state-of-the-art continuous wave dye lasers operating in the ultraviolet, molecular beams, and on-line data acquisition systems. The U.S. and Dutch groups bring complementary expertise and approaches in high resolution spectroscopy and chemical dynamics to this joint research. Although they now have similar equipment, the Dutch group is the acknowledged leader in this area of molecular spectroscopy. Their prior collaboration made possible the design and fabrication of a new generation of "laser spectrograph" at the University of Pittsburgh. The absorption of light by a molecule creates an electronically excited state. It is the properties of this state, rather than the ground state, that dictate the chemical and physical behavior of the system. The sophisticated techniques being used in this collaborative research will reveal molecular eigenstate structures of several compounds of biological and chemical interest for the first time. This knowledge will make it possible to control chemical bond breaking and forming mechanisms, and thus permit the control of chemical reactions with light.