The chemical zeno effect in exchange-coupled radical Pairs: 1. Triplet radical pairs

It was shown that spin-selective intracage recombination could influence the limiting triplet-singlet conversion stage and, therefore, the whole chemical dynamics. An increase in the rate constant for intracage recombination w decreases the S-T evolution frequency and changes its character by transforming the oscillating spin conversion mode into “kinetic.” As a result, an increase in w can decrease the yield of intracage recombination products and increase the yields of products formed in competing extracellular radical reaction channels. The chemical Zeno effect and its consequences are an analogue of the quantum Zeno effect (quantum evolution “deceleration” caused by successive measurements), and spin-selective recombination is similar to quantum state measurements.