CHARACTERISTICS OF THE PHOTOLUMINESCENCE PROPERTIES OF PYRENE ADSORBED ON AND DOPED INTO SILICA-BASED MATERIALS

The photophysical and photochemical properties of the pyrene molecules which are encapsulated into solid matrices and adsorbed on solid surf aces are reviewed. The fluorescence of the pyrene molecules adsorbed o nto the silica gel surface at lower surface coverage is mainly due to the monomer emission of pyrenes. When the surface coverage of pyrene i s increased, the excimer fluorescence of pyrenes can be observed owing to the formation of biomolecular ground-state associations. Consequen tly, the pyrene fluorescence spectra were successfully applied to moni tor changes in the polarity of sol-gel systems during the sol-to-gel-t o-xerogel transition processes by the sol-gel method.