Quenching of excited singlets by peroxides and hydroperoxides

Abstract

Energy transfer from a variety of aromatic hydrocarbons and ketones to di- tert-butyl peroxide, tert-butyl hydroperoxide and hydrogen peroxide was examined by following the sensitizer fluorescence yield as a function of the peroxide concentration. For the aromatic hydrocarbons the rate constants range from 1.8 × 10 9 M −1 s −1 for benzene to less than 2.3 × 10 5 M −1 s −1 for coronene. The quenching rate constant is almost solvent independent and does not depend appreciably upon the donor properties of substituents but it depends strongly on the sensitizer energy. The results are compatible with a quenching mechanism involving energy transfer to ground state peroxide molecules with an OO bond length greater than the equilibrium value.