Activation-controlled hydrogen abstraction by benzophenone triplet

Through nanosecond flash photolysis measurements, activation energies for hydrogen abstraction by benzophenone triplet have been shown to correlate with solvent molecular structure. We demonstrate that two successive processes result in photoproduct generation. One, triplet quenching, is independent of macroscopic viscosity, and is not simply reflected in the observed quantum yield. The second process involves separation of two caged radicals, and does not occur in rigid media.