Brillouin light scattering study of glassy sorbitol

Brillouin light scattering has been used to investigate the density fluctuations of the fragile glass-former sorbitol in the GHz frequency range and at temperatures between 20 and 294 K. Longitudinal acoustic sound velocity and attenuation data are here reported and discussed. These data are used to test the existence of a correlation between elastic properties of glasses and viscous properties of the corresponding deeply undercooled melts above the glass transition temperature, T(g). In particular, and as for other fragile systems, the ratio of the vibrational to the relaxational compressibility at T(g) is found to be basically independent of fragility.