Quenching of the Yt-Base Fluorescence by Heavy-Atom Induced Intermolecular Singlet-Triplet Energy Transfer

Quenching of the Ff base fluorescence by a series of halogen derivatives of benzene and naphthalene was measured in dioxane. For the naphthalene derivatives, the presence of the heavy atom in the acceptor molecule was found to affect strongly the fluorescence quenching rate constant, whereas no such effect was observed for the benzene derivatives. The fact is explained with the as-sumption of a singlet-triplet energy transfer from the Yf base molecules to the naphthalene derivatives.