Fast Electron Transfer Kinetics in Photosystem I from Transient EPR-Spectroscopy at Room Temperature

Following light excitation of the donor P700 and primary charge separation electron transfer in photosystem I (PSI) is believed to proceed via a chain of membrane bound acceptors termed Ao, A1, FX, FA, FB /1,2/. Transient EPR-spectroscopy of spin polarized signals provides a useful tool to study the kinetics of these processes provided the transfer times fall within the time resolution presently approaching the physical limit around 10 ns.