EFFECTS OF OXYGEN AND TEMPERATURE ON PHOSPHORESCENCE AND DELAYED FLUORESCENCE OF ERYTHROSIN-B TRAPPED IN SOL-GEL SILICA

Room temperature phosphorescence (RTP) of erythrosin B in sol-gel sili ca was studied in ambient air, in pure oxygen and in vacuum. Oxygen wa s found to be an effective quencher of RTP. The phosphorescence and de layed fluorescence data at oxygen pressures higher than 20 mbar can be interpreted by Stern-Volmer diffusional theory. The quenching rate co nstants of oxygen were determined to be 0.0151 and 0.0111 mbar(-1), re spectively for phosphorescence and delayed fluorescence. Phosphorescen ce spectrum at 97 degrees K was measured. More than 2-folds enhancemen t of phosphorescence intensity was achieved at 97 degrees K. The phosp horescence quantum yields in vacuum were determined as 5.0% and 2.04% at 97 degrees K and at room temperature, respectively. (C) 1998 Elsevi er Science S.A. AU rights reserved.