Time Resolved Fluorescence in Doped Aerogels and Organosilicate Glasses

The fluorescence decays of anthracene, 9,10‐dichloroanthracene and 6‐(methoxy)‐1‐(3‐sulfopropyl)‐quinolinium in sintered aerogels and of anthracene in organosilicate glasses were determined employing a precise single photon counting technique. For aerogels and organosilicate glasses, synthesized from methyltrimethoxysilane and tetramethoxysilane a biexponential decay was found. The dependence of the fluorescence behaviour on the cross linkage of the network and the adsorbed solvent indicates that the short decay is due to an efficient quenching by the network, whereas the slow component is influenced by adsorbed solvent. For aerogels the effect of aging was also investigated. For organosilicate glasses with a reactive organic sidegroup (γ‐glycidyloxypropyl) the short decay is interpreted by a decay law containing a broad distribution of life times (Kohlrausch‐Williams‐Watts). In this case the measurement of the fluorescence decay shows evidence of a heterogeneous microstructure which contains inorganic and organic network components.