Time-resolved spectroscopic study of phosphorescence and delayed fluorescence of dyes in silica-gel glasses

Time-resolved spectroscopy was performed to study the lowest triplet state lifetimes of erythrosin B, eosin Y and fluorescein trapped in silica-gel glasses. Room temperature phosphorescence (RTP) and delayed fluorescence (DF) were observed for erythrosin B and eosin Y. Only delayed fluorescence was observed for fluorescein. The decay lifetimes of RTP and DF were measured. The singlet–triplet intersystem crossing rate was determined. For comparison, spectroscopic measurements were also made of erythrosin B, eosin Y in gelatin, and fluorescein in boric acid. The intensity dependence of singlet–singlet absorption of organic dye molecules in sol-gel silica was studied.