DYNAMICAL PROPERTIES OF WATER-METHANOL SOLUTIONS - BRILLOUIN AND DEPOLARIZED RAYLEIGH-SCATTERING

We have performed Brillouin and depolarized Rayleigh light scattering on water-methanol solutions as a function of methanol molar fraction a nd temperature. For this system, molecular-dynamics (MD) simulation pr edicts that a shell of water forms around a methanol molecule, predict ion which has been recently confirmed by neutron diffraction experimen ts. The results obtained by light scattering and presented here confir m previous observations and show, in addition, an increase of the stab ility in time of the water structure in the shells when temperature de creases and methanol concentration approaches a particular value.