Pressure dependence of the refractive index and of the sound velocity of methanol-ethanol solution: A Brillouin scattering study

The pressure dependence of the refractive index n(P) and of the longitudinal acoustic velocities of 4.1 methanol-ethanol solution have been measured in a diamond anvil cell up to 8.1 GPa. We utilize Brillouin scattering methods for this determination and detect, in the same back scattering configuration, acoustic wave propagation parallel to the faces of the diamond anvils as well as along the incident laser radiation direction. We also deduce that the polarizability of the fluid is reduced by about 15% over the pressure range studied.