PROBING INORGANIC MATRICES WITH ORGANIC-MOLECULES

The coupling of low temperature processing and gel-glass doping with organic photoactive or electroactive molecules will open new opportunities for optical and electrooptical applications. The requirement of precise control of compositional and pore surface variations in cage trapped molecules is necessary to the preparation of new optical and electrooptical gel-glasses. The methods used for achieving this goal are related. These involved combinations of molecular precursors and polymerizing conditions. Examples are given for fluorescent gel-glasses, room temperature phosphorescent gel-glasses and photochromic gel-glasses with a combination of optical properties. Gel-glass dispersed liquid crystal (GDLC) with electrooptical properties are also described. The sensitivity and the photophysical behavior and properties of the trapped organic molecules have been used to observe the structural changes that occur in a polymerizing system of silicon alkoxides in ceramer composites and in a reversed phase silica obtained by the sol-gel technique. Variable-frequency (0.01-120 MHz) phase and modulation analysis are introduced to monitor the spectral properties of the rhodamine 6G-doped TiO2 spherical particles, yielding information about the entrapping medium. This information is useful to study the identity of the different rhodamine 6G emitting species in the TiO2 particles.