Antenna exciton trapping kinetics as a probe of primary electron transfer heterogeneity in the photosynthetic reaction center

The multipicosecond nonexponential decay of the electronically excited primary electron donor, P∗, observed in isolated photosynthetic reaction centers, is just as readily explained by multistep homogeneous electron transfer as by single-step heterogeneous transfer. With the aid of a one-antenna-site hopping model, it is shown here that the exciton trapping kinetics in the associated core antenna theoretically can be used to distinguish homogeneous from heterogeneous mechanisms of primary electron transfer in the reaction center.