Radical pair dynamics observed with pulse-mode product-yield-detected ESR

Three pulse sequences have been employed for laser and microwave-pulse irradiation in the pulse mode product-yield-detected ESR technique to detect the dynamical feature of transient radical pair. In this method, the decrease in spin adduct yield as functions of delay times for irradiation/termination of the microwave pulse after the laser pulse are simulated with the Runge-Kutta method for a detailed reaction model to obtain the rate constants of cage product formation, escape of the radical pair, as well as the hydrogen abstraction reaction. As the representative reaction systems, photoreduction of anthraquinone, anthraquinone-2-sulfonate, and benzophenone in SDS micellar solution were employed. Effects of cyclohexene, added as a hydrogen donor, NaCl and Ethanol, added to change the microviscosity of micelle, on these reaction rate constants have been tested.