Inhomogeneous distribution of organic molecules adsorbed in sol-gel glasses

The effects of the porous matrix upon the radiative characteristics of quin ine sulphate doped sol-gel glasses are investigated, The broadenings of the absorption and fluorescence spectra are explained by the attachment of the molecules on distorted sites or in a non-planar fashion, creating an inhom ogeneous distribution of adsorbed molecules. For this reason, each emitting center relaxes with its own characteristics. This inhomogeneous distributi on is also supported by the non-exponential and the wavelength dependence o f the fluorescence decay. (C) 1999 Elsevier Science B.V. All rights reserve d.