Optically Controlled Electron-Transfer Reaction Kinetics and Solvation Dynamics: Effect of Franck-Condon States.

Experimental results for optically controlled electron-transfer reaction kinetics (ETRK) and nonequilibrium solvation dynamics (NESD) of Coumarin 480 in DMPC vesicle show their dependence on excitation wavelength λex. However, the celebrated Marcus theory and linear-response-theory-based approaches for ETRK and NESD, respectively, predict both of the processes to be independent of λex. The above said lacuna in these theories prompted us to develop a novel theory in 1D space, where the effect of innumerable Franck-Condon states is included through λex. The present theory not only sheds light on the origin of failure of the existing theories but also gives the correct trend for the effect of λex on ETRK and NESD. More importantly, the calculated results of NESD are in excellent agreement with the experimental results for different values of λex. The new theory will therefore advance the knowledge of scientific community on the dynamics of photoinduced nonequilibrium processes.