Spectroscopic study of sulforhodamine 640-doped sol–gel silica

The sol–gel process is a technique which provides a low-temperature route for the preparation of organic dye-doped porous silica glass. Extended UV transmission was observed for HCl-catalysed sol–gel silica. Properties of a solute may differ greatly between a free solution and that solution confined in pores of a sol–gel glass. Absorption and fluorescence properties of sulforhodamine 640-doped silica samples prepared by sol–gel process were investigated. In the TEOS-derived gel, the emission of the dye does not shift during aging but exhibits a large change during drying. The emission maximum of sulforhodamine 640 blue shifts was discussed as a function of increasing rigidity of the surrounding matrix.