Study of the magnetic-field-dependent behaviour of radicals generated photochemically from benzil in micellar media

Abstract

Excited benzil, encaged in sodium dodecylsulphate (SDS) surfactant in aqueous solution, generates a radical pair (benzil ketyl radical and SDS radical) on hydrogen abstraction from the micelle. The lifetime of this triplet-born radical pair is dependent on the magnetic field, reaching saturation at fields greater than 1 kG. An intermediate radical pair, as demonstrated by the occurrence of a magnetic field effect, is also observed on ∏∏^∗ excitation of this fairly labile molecule. In addition, Cu²⁺ ions quench the effect of the magnetic field on the decay of the radical pair. From the temporal response and the magnetic field effect, it is concluded that radicals initially generated by n∏^∗ and ∏∏^∗ excitation are different.