Turbidity in the binary fluid mixture methanol-cyclohexane.

Abstract

The turbidity of a near-critical binary fluid mixture, methanol-cyclohexane, has been carefully measured above its (upper) critical consolute point. These measurements covered the reduced temperature region ${10}^{\mathrm{\ensuremath{-}}5}$${10}^{\mathrm{\ensuremath{-}}2}$ and allowed theoretical predictions for the critical exponents \ensuremath{\nu} and \ensuremath{\gamma} to be verified. The amplitude ${\ensuremath{\xi}}_{0}$ of the correlation length was also determined to be 3.24\ifmmode\pm\else\textpm\fi{}0.2 A\r{} while ${\ensuremath{\tau}}_{0}$ was (6.9\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. Our result for ${\ensuremath{\xi}}_{0}$ is compared with other experimental determinations, and when combined with ${\ensuremath{\tau}}_{0}$ and coexistence curve data, is used to determine the ratio R=${\ensuremath{\xi}}_{0}$(${B}^{2}$/${k}_{B}$${T}_{c}$${\ensuremath{\chi}}_{0}$${)}^{1/}$ ${3=0.71}_{5}$\ifmmode\pm\else\textpm\fi{}${0.02}_{4}$ which is consistent with the prediction 0.65--0.67 from two-scale-factor universality.