Charles F. Kettering Research Laboratory, Yellow Springs, OH 45387, U.S.A.
Abstract:
The decay time of flash-induced absorption changes in a Photosystem-II subchloroplast fragment is very temperature sensitive down to 210 K, below which it remains constant at 1.25 ± 0.05 ms. The difference spectrum from the near-infra-red to the ultraviolet regions indicates that the monophasic decay represents charge recombination between P-680+ and the reduced primary acceptor. The charge recombination proceeds by electron tunneling. The P-680 concentration in the TSF-IIa fragment was estimated to be one in 30 ± 5 total chlorophyll molecules.