Journal of Physical Chemistry B, Vol.102, No.2, 464-472, 1998
Magnetic field effects on the recombination kinetics of radical pairs
The recombination kinetics of radical pairs able to react only via the singlet channel are calculated within the framework of the radical pair mechanism, treating nuclear spins semiclassically. The form of the decay, which is in general nonexponential, depends on the applied magnetic field strength and the rate of electron spin-lattice relaxation. Analytical expressions are derived for the limiting cases of zero and high field, with very slow or very fast relaxation. The theory is tested and verified by measuring the decay of the secondary radical pair of photosynthetic bacterial reaction centers at low temperatures.