An investigation of the factors which govern the rate and efficiency of electron transfer reactions will be conducted. The effect of spacers separating donor and acceptor groups will be evaluated by measuring photoinduced charge separation rate constants and emission spectra as a function of temperature and calculating free energies of electron transfer. Picosecond photocalorimetry will be used to evaluate enthalpy and volume changes which occur upon electron transfer. Finally, through-solvent electron coupling and its impact upon electron transfer will be investigated in structurally rigid molecules. Correlations between transfer rate constants, electronic coupling matrix elements, and solvent band structure will be analyzed. %%% A process which is common to a large number of chemical reactions is the rapid transfer of electrons. With this grant from the Organic Dynamics Program, Profssor Matthew Zimmt of Brown University will investigate the factors which govern the rate of electron transfer processes which are complete within a few trillionths of a second. The parameters which influence electron transfer will be investigated using molecules specially designed so that both the distance between donor and acceptor groups and the identity and positions of the intervening atoms are well-defined. The results of the study may make it possible to design molecular systems which will maximize electron transfer efficiency.
