In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Graham Fleming in the Chemistry Department and Lauren Mets in the Department of Molecular Genetics and Cell Biology at the University of Chicago will conduct experimental and theoretical studies of photosynthetic energy- and electron-transfer. The PIs will investigate the transfer of excitation among pigment molecules in photosynthetic antenna molecule, processes which occur on the femtosecond time-scale and longer, using ultrafast nonlinear spectroscopy. Theoretical models will be constructed to help explain such dynamical data as the vibrational energy and phase relaxation rates. The goal of this research is to characterize the interactions between chromophores, the light-absorbing parts of molecules, as well as the strength of these interactions and the time scales on which they occur. These studies should help in the understanding of the remarkable efficiency of photosynthesis in both plants and photosynthetic bacteria.