Transient grating experiments on CCl₄-filled porous glasses

Abstract

We performed heterodyne detected transient grating experiments on porous glasses, characterized by different pore sizes, filled with liquid carbon tetrachloride. The measured signal shows an articulated profile characterized by different dynamic phenomena. In the faster time scale (t < 0.1 µs) the acoustic processes take place. In the slower time scale(t > 0.1 µs) unexpected relaxation/thermal diffusion phenomena show up. In order to measure and address these dynamic features, we studied the effect of sample preparation on the experimental signal. Furthermore, we measured the sound velocity and attenuation as a function of sample treatment and temperature. The reported data shows clearly how the unremoved water contained in the pores can play a relevant role in the measurement of physical parameters of liquid filled-glass systems.

Acknowledgments

The research has been performed at LENS. We would like to thank A. Fontana, M. Montagna and G. Ruocco for helpful discussions and suggestions. This work was also supported by the EC grant N. RII3-CT-2003-506350, by CRS-INFM-Soft Matter (CNR) and MIUR-COFIN-2005 grant N. 2005023141-003.