This project in Experimental Physical Chemistry is designed to elucidate the flow of vibrational and rotational energy when it is deposited in isolated molecules which have been cooled to low temperatures by free-jet expansion. Dr. J. D. McDonald will conduct a variety of experiments using a combination of laser spectroscopic and free-jet expansion techniques to probe the intramolecular vibrational relaxation process. One experiment will use visible or ultraviolet stimulated emission pumping spectroscopy to measure the spectrum of molecular eigenstates in the ground electronic state of alpha-dicarbonyl molecules. A second experiment will use infrared pump-visible probe double resonance to gain similar information and to learn about the nature of the relaxed "bath states" by studying the visible fluorescence of the excited molecules. A third experiment will probe a different subset of the bath states in the same molecules as the previous experiment by spectrally resolving their infrared fluorescence. The last experiment will attempt many of the same types of studies with time resolution on a picosecond scale. Collectively these four techniques will provide a very complete view of the intramolecular vibrational and rotational relaxation process in several molecular systems.
