ELECTRONIC-ENERGY TRANSFER AND TRAPPING IN QUINIZARIN-DOPED ALUMINOSILICATE SOL-GEL GLASSES

Time-resolved fluorescence lifetime and depolarization measurements are used to investigate electronic excitation energy transfer and trapping in quinizarin-doped aluminosilicate sol-gel glasses. At low quinizarin concentrations donor-donor electronic energy transfer is dominant, however, at higher concentrations energy trapping is significant. The concentration-dependent dynamics suggest a dimer-like trap species and a nearly isotropic distribution of chromophores within the porous xerogel matrix. A comparison of wet gels versus porous xerogel glasses indicates that energy traps exist in the gel and that the number of traps does not significantly increase during formation of the (20 times) higher concentration xerogel glass.