Primary photochemical processes in aromatic molecules. Part 13.—Bi-photonic processes

Abstract

Under certain conditions, photochemical changes may result from the absorption of light by metastable excited (triplet) states. In solutions of aromatic compounds in rigid aliphatic hydrocarbon glasses, two such processes occur: these are the ionization of the solute (detectable by thermo-luminescence on subsequent heating) and sensitized dissociation of the solvent to give free radicals (detectable by electron spin resonance) and hydrogen atoms: the latter are not trapped but abstract another hydrogen atom from the solvent or the solute, so that the production of solute radicals (e.g., benzyl from toluene) is also biphotonic.