Magnetic field and isotope dependence of the reaction rates of micellized triplet radical pairs

Nanosecond time resolved optical absorption studies of the isotopic dependence of the magnetic field effect on geminate triplet benzylic radical pair reaction dynamics in micelles of HDTCl are reported. The isotopic susceptibilities of the T_± radical pair reaction rate constants in small (<50 G) and intermediate (100-500 G) fields are substantially different. The magnitude and field dependences of the isotopic effects are discussed in terms of the mechanisms of radical pair spin evolution (intersystem crossing) in the presence of magnetic fields.