Fluorescence quenching of the diphenyl ketyl radical

Abstract Excitation of α-phenylbenzoin solution in acetonitrile generates emission from the diphenyl ketyl radical with a lifetime of 3.7 ns. This is quenched by methyl methacrylate and p -chlorobenzenediazonium tetrafluoroborate. The rate constant with diazonium salt is about the same for ground and excited radicals, while reaction of the excited radical with methyl methacrylate is 3 × 10 5 times faster than for the ground state.