Excitation migration and trapping in homogeneous and heterogeneous lattices

Abstract

Energy transfer in arrays of photosynthetic antenna pigments containing a photochemical trap is studied combining the transition probability matrix method with random walk theory and experimental data on fluorescence lifetimes and overall trapping efficiencies in systems with open and closed photochemical trap. New exact expressions for the fluorescence decay time and the trapping at infinite time are derived that contain the probability to escape from the trap as a single parameter. Two approximate relations for the fluorescence decay time, τe, and T, the probability that trapping has occurred at infinite time, are derived that can be applied to homogeneous and heterogeneous antenna arrays: , where τt is the characteristic time of photochemical trapping, τc1 the fluorescence decay time for closed traps, f the probability to escape from the trap, and p the equilibrium probability to find the excitation on the trap. p is independent of the initial conditions (selective or random excitation); p = 1 / N for ...