Resonant radiofrequency magnetic field effects on a chemical reaction

Observations of the effect of a radiofrequency magnetic field on the progress of a chemical reaction are reported. It is shown that the fluorescence of an exciplex formed in the photoreaction of anthracene-d10 and 1,3-dicyanobenzene (DCB) is attenuated when a 30–40 MHz oscillating field is applied. The effect is interpreted in the framework of the radical pair mechanism, in terms of a change in the extent of singlet↔triplet interconversion in the {anthracene cation-DCB anion} radical pair when the oscillating field is in resonance with hyperfine splittings in the DCB anion radical.