Onset of the α-relaxation in the glass-forming solution LiCl–6H2O revealed by Brillouin scattering techniques

We measured the dynamic structure factor of the liquid and glassy phases of the LiCl–6H2O solution by means of inelastic scattering of radiation in the visible, UV, and x-ray range, between 1 GHz and 10 THz, and by means of photon-correlation spectroscopy, between 0.01 Hz and 20 kHz. The measurements were performed in the temperature range between 353 and 80 K. Our data show that a single-relaxation process exists at high temperature, which has features similar to those of the single relaxation of pure water. Upon cooling the system below ∼220 K, this single mode starts to differentiate two processes, a structural (α−) and a secondary (β−) relaxation. As the temperature is decreased, the β-relaxation is the vanishing continuation of the single, high-temperature process, while the onset of the α-relaxation occurs at the expense of the β-process.