Fluorescence properties of rhodamine B-doped SiO2-TiO2 films prepared by sol-gel process

The sol-gel coating processes of the rhodamine B-doped SiO2-TiO2. system, a nd the influence of the compositions of the SiO2-TiO2, system on the fluore scence properties of rhodamine B-doped films have been investigated. The ma in absorption band of rhodamine B-doped films can be attributed to the rhod amine B monomers, and only a very weak absorption band of the dimer can be observed. The relationship between absorbance and film thickness was linear for the rhodamine B-doped SiO2-TiO2 films. The single emission band in flu orescence spectrum of rhodamine B-doped films can be attributed to transiti ons from the lowest-lying level of the first excited electronic state to th e electronic ground state of rhodamine B monomers. The fluorescence intensi ties of rhodamine B-doped SiO2-TiO2, films obviously increased with the inc rease of film thickness. The relationship between fluorescence intensity an d film thickness was also linear for the rhodamine B-doped SiO2-TiO2 films. The compositions have significant influence on the fluorescence intensitie s of the rhodamine B-doped SiO2-TiO2 films. The fluorescence intensities de creased obviously with increase of TiO2 when the content of TiO2, was more than 30%. (C) 2001 Elsevier Science B.V. All rights reserved.