Temperature anomalies of hypersound velocity and specific heat ratio in liquid Quinoline

Results of an extensive study of dynamic polarized (VV) and depolarized (VH) Rayleigh-Brillouin light scattering in Quinoline as a function of temperature are presented. The VV spectrum is analyzed by taking into account the fine structure (shear dip) of the VH spectrum. The hypersound velocity u(T) and the Landau-Placzek ratio γ(T) have been calculated from the frequency shift of the Brillouin lines and the ratio of the integrated intensities of the non-shifted Rayleigh line to the two Brillouin lines. Under the conditions of high-purity and long equilibration times, the temperature variations of both u(T) and γ(T) show two reproducible anomalies centered at about 17 and 42 °C. We discuss an interpretation of the anomalies based on local structure changes, and possible relations of these anomalies to liquid-liquid phase transitions in equilibrium liquids.