Spin catalysis: three-spin model

Recently it has been shown that in a radical triad one of the radical partners affects the chemical reactivity of the other pair, catalyzing the spin transformation of this pair. The phenomenon is shown to be caused by the exchange interaction between the radical triad partners which stimulates doublet-doublet spin evolution and produces the oscillating triplet-singlet spin conversion of the selected radical pair in the radical triad under the influence of the odd radical spin. The theory of the phenomenon is developed and the equations for the rate of spin evolution in a three-spin system are derived. A new type of quantum beats is predicted.