Internal magnetic field effect of transition metal ions on the photochemical reaction of naphthoquinone in micelles

Abstract

With the aid of the time resolved ESR and transient optical absorption spectroscopy, the effect of transition metal ions on the photochemical reaction of naphthoquinone in micelles was investigated in the absence and presence of external magnetic fields below 1 T. The paramagnetic metal ions accelerated the relaxation of the component radicals in the generated radical pair. All quenching rate constants of the paramagnetic ions were around 7 × 10 8 mol −1 dm −3 s −1 and did not show any dependence on their magnetic properties. This result shows that the relaxation of the electron spins by the paramagnetic transition metal ions is induced by the strong exchange interaction between the radical pair in a micelle and the ions at the water interface of the micelle.