TRANSFER OF SPIN CORRELATION BETWEEN RADICAL PAIRS IN THE INITIAL STEPS OF PHOTOSYNTHETIC ENERGY-CONVERSION

A simple theoretical description of the transfer of electron spin-corr elation from one radical pair to another is presented. Solution of the coupled equations of motion of the two radical pairs, yields simple e xpressions for the spin-polarized electron paramagnetic resonance inte nsities of the secondary pair in terms of the magnetic and exchange in teractions of the electron spins, and the rates of the forward and bac kward electron transfer reactions of the primary pair. This work is se t in the context of the initial steps of bacterial photosynthesis in w hich the rate of formation of the secondary radical pair is reduced by Fe2+ removal or quinone substitution.