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

Abstract

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 gamma(T) have been calculated from the frequency shift of the Brillouin lines and the ratio of the integrated intensities of the non-shifted Rayleigh fine to the two Brillouin fines. Under the conditions of high-purity and long equilibration times, the temperature variations of both u(T) and gamma(T) show two reproducible anomalies centered at about 17 and 42 degrees 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.