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 λ_ex. 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 λ_ex. 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 λ_ex. 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 λ_ex on ETRK and NESD. More importantly, the calculated results of NESD are in excellent agreement with the experimental results for different values of λ_ex. The new theory will therefore advance the knowledge of scientific community on the dynamics of photoinduced nonequilibrium processes.