Transient grating experiments on CCl4-filled porous glasses

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 tirne scale (t 0.1 mu s) the acoustic processes take place. In the slower tirne scale(t > 0.1 mu s) 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.