Laser light scattering study of a ternary liquid mixture: Ethanol-water-chloroform

The intensity and Rayleigh linewidth of light scattered by concentration fluctuations in a ternary ethanol-water-chloroform system have been studied as a function of angle and temperature. Critical exponents γx, νx, and η obtained from the angular distribution of scattered intensity measured at constant compositions and different temperature distances from the plait point gave values of 1.50, 0.765, and 0.077, respectively. The results demonstrate the critical exponent renormalization, show first evidence of the nonzero critical exponent η in a three-component fluid system, and are not inconsistent with the scaling relations. In view of the renormalization which provides us with a stronger temperature dependence on the correlation length ξ, the critical region (K ξ> 1) can be reached even at T − Tc = 0.5°C. Thus, we are able to compare our experimental linewidth and hydrodynamic shear viscosity data with the Kawasaki theory at very large values of K ξ ≃ 50. Our experimental observations agree very well with the mode-mode coupling theory of Kawasaki after corrections for vertex, nonlocality, and frequency dependence of the shear viscosity and deviation of the Ornstein-Zernike correlation function.