Study on the coherent spin motion of the radical-ion pair formed in the laser photolysis of N,N,N′,N′-tetramethyl-1,4-phenylenediamine in 2-propanol Original Research Article

The microwave-induced coherent spin motion of the radical-ion pair formed in the photolysis of TMPD (N,N,N′,N′-tetramethyl-1,4-phenylenediamine) in 2-propanol is shown at room temperature. The delayed fluorescence from the excited singlet state created by the back electron transfer in the radical-ion pair is used to monitor the singlet radical-ion pair. The satellite-like alternating spectrum and the oscillating time evolution of the signal are observed, and they are well reproduced by employing a simple quantum-mechanical calculation. Accordingly, the TMPD/2-propanol system is found to be ideal for demonstrating the radical-pair spin motion. The long-persisting coherent signal of this system implies the weakly interacting feature of this radical-ion pair.