Correlation Effect in the Time-Dependent Concentration Fluctuations of the Isobutyric Acid—Water System near its Critical Mixing Point

Publisher Website
Google Scholar
Abstract
Measurements by the laser homodyne ``self‐beating'' technique were made of the quasielastic Rayleigh linewidth in a critical binary liquid mixture, isobutyric acid—water (Tc=26.12°C), at temperature distances 0.071°, 0.196°, 0.36°, 0.73°, and 1.16°C above the critical solution temperature over a range of scattering angles. Deviations from the Landau—Placzek theory on the K2(K=ks, k=2π/λ, s=2 sinΘ/2) dependence of the half‐width of the central (Rayleigh) component (T) have been observed. Experimental data are in good agreement with Fixman's modification which takes into account the effect of long‐range correlations in binary liquid mixtures and has the form T=aK2(1+K2/κ2) with κ corresponding to the inverse correlation length of Ornstein and Zernike.