Simple analytical approach to the description of flash-CIDNP formation for ion radicals

The simple analytical expressions for the stationary bimolecular rate constants of recombination of charged radicals in external magnetic field were obtained for the case of high magnetic field, stepwise exchange integral and contact recombination. A comparison of the analytical and the precise numerical calculations shows good accuracy of the proposed approach. Also discussed is the non-trivial influence of solvent polarity and viscosity on the rate constants via singlet—triplet conversion efficiency.