On the verification of different approaches describing spin-selective radical recombination

The problem of verifying various approaches to account for the effect of spin-selective recombination of radicals on the quantum state of the radical pairs escaping recombination is discussed. Here we propose the use of radical triads for the verification. It is shown that in radical triads ABC a spin-selective reaction between radicals B and C modifies spin correlation between radicals A and B. Different approaches predict different time dependences for these changes, e.g., the population of the singlet spin state of the radical pair AB decays with different rates. Possible experimental checks of these predictions are discussed.