Dynamics of water-ethanol mixtures studied by light scattering

Brillouin scattering of water-ethanol binary mixtures have been measured in the temperature range from room temperature to 343 K as a function of ethanol concentration. A maximum appears at 12 ethanol mol% in the sound velocity and at about 50 mol% in the absorption coefficient all at room temperature. Raman scattering of heavy water-ethanol mixtures was also measured at room temperature as a function of concentration. The concentration range from 0100 mol% is divided into three ranges and the behavior of the acoustic properties was discussed with three cluster models; the circular clusters are dominant in the concentration range of 0-12 mol%, layered clusters in the range of 1250 mol%, pure ethanol chain clusters in the range of 50-100 mol% at room temperature. These results are consistent with the concentration variation of OH stretching band of Raman spectra and the results in literatures.