Inhomogeneous distribution of organic molecules adsorbed in sol-gel glasses

The effects of the porous matrix upon the radiative characteristics of quinine 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 inhomogeneous distribution of adsorbed molecules. For this reason, each emitting center relaxes with its own characteristics. This inhomogeneous distribution is also supported by the non-exponential and the wavelength dependence of the fluorescence decay. (C) 1999 Elsevier Science B.V. All rights reserved.