The Landau–Placzek ratio of water–alcohol binary mixtures

Rayleigh–Brillouin scattering was performed for water and alcohol (methanol, ethanol, 1-propanol and 2-propanol) binary mixtures. The Landau–Placzek ratio depends on both concentrations and molecular weights, and qualitatively corresponds to the ultrasonic absorption. Microscopic concentration fluctuation mainly affects the Landau–Placzek ratio of water–alcohol mixtures.