Influence of thermal treatment in high and low frequency dynamics of silica porous systems

Abstract Absorption and Brillouin light scattering measurements were performed, before and after the thermal treatment on silica xerogels and aerogel in the 500 ρ 3 density range. We found that the high frequency dynamics in porous systems, is very similar to the vitreous silica one. On the contrary, low frequency dynamics observed by Brillouin scattering, is very sensitive to the porosity and to the water content.