Pulsed microwave irradiation effects on the dynamic behavior of a photochemically generated radical pair in a micellar solution

The radical pair dynamics in a photochemical hydrogen abstraction reaction of 2-methyl-1,4-naphthoquinone in a sodium dodecylsulfate micelle was modulated by a microwave pulse. After a short resonant 180° microwave pulse, the recombination of the radical pair was enhanced, its rate constant being determined to be (8.3±0.8)×106 s−1. Other kinetic parameters were determined by the scanning of the microwave pulse position as follows: the formation of the radical pair (3.3±0.3)×107 s−1, the relaxation rate from the triplet (T±1) levels to the singlet–triplet (T0) mixed one (3.3±0.3)×105 s−1 at 331 mT, and the radical escape rate (5.8±0.6)×105 s−1.