Triplet-triplet extinction coefficients via energy transfer

Abstract

The triplet-triplet extinction coefficients of seventeen compounds have been determined in cyclohexane and benzene at room temperature by a method involving energy transfer. Large changes in extinction coefficient at the wavelength maximum ε(λmax) were observed upon changing solvent from cyclohexane to benzene. Values of ε(λmax) were determined relative to a value of ε(λmax) for the ketyl radical (ϕ2ĊOH) of 3220 M–1 cm–1 in water, assuming no change of oscillator strength with solvent. A number of triplet transfer rates, and other reactivities of benzophenone triplet and ketyl radicals, were also estimated.