Molecular Triplet State Properties and Processes

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In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Weisman will investigate the dynamics and photophysics of triplet spectroscopic states of both gas-phase and solution-phase molecules. The gas-phase studies will extend investigations of triplet collision dynamics to pyrimidine, pyridine, sym-triazine, and naphthalene in order to understand the dependence of triplet-state lifetime on excess energy. Time-resolved optical absorption spectroscopy will be used to gather data. These data will be analyzed using Master Equation simulations to provide results that can be more easily compared with theoretical calculations. The energetics and dynamics of solution-phase fullerene triplet-state molecules will be examined using transient absorption, photoacoustic, and emission spectroscopic measurements. Molecules to be studied include C60, C70, and higher fullerenes. The results will form a data base of photophysical properties for understanding excited-state behavior in these compounds and for planning and optimizing potential fullerene applications.Triplet states of polyatomic molecules are important to investigate because such molecules typically persist much longer than the molecule's other excited states while displaying increased tendencies for chemical reaction, electron transfer, and energy transfer. The identity of the excited state that a molecule can find itself in can also determine or alter the course or efficiency of a particular chemical reaction of interest. The studies in this project are of fundamental interest, but they can also impact practical applications, such as optical data storage systems using fullerene-derived compounds.