Conrolling of radical-ion pair reactions by microwave radiation: photoconductivity-detected magnetic resonance

Photoconductivity-detected magnetic resonance has been performed successfully as a new investigation method for transient radical-ion pairs. The chemical reaction of radical-ion pairs is controlled by microwave radiation. The photoionization system of TMPD (N,N,N′,N′-tetramethyl-1,4-phenylenediamine) in alcohol is employed. The data show the broadened linewidth of the radical-ion pair spectrum that may be influenced by the microwave field and/or the dynamic motion of the radicals. This observation method is a powerful way of studying the dynamics of transient radical-ion pairs formed in photochemical and photobiological reactions that involve electron transfer reactions.