RAMAN-SPECTROSCOPY AS A MORPHOLOGICAL PROBE FOR TIO2 AEROGELS

We report on the application of Raman scattering as a probe to follow the structural evolution of TiO2 aerogels. We have traced the evolutio n of the 142 and 630 cm(-1) E(g) anatase peaks as a function of morpho logy. The results have been analyzed in terms of the q vector relaxati on mechanism which predicts a unique relation between particle size an d features of the Raman spectra. Since the phonon dispersion of anatas e is not known, we have used the analogous rutile dispersion. There is good agreement between the particle sizes evaluated from the model an d those determined by X-ray diffraction. Our results demonstrate that Raman spectroscopy can be an effective tool in monitoring the evolutio n of these aerogel systems.