Asymmetry in Critical Light Scattering from Binary Mixtures of Phenol and Water in the Two-Phase Region

Abstract

Previously reported experiments by Pusey, Bak, and Goldburg showed an asymmetry in the light scattering in the high- ($h$) and low- ($l$) density phases of critical mixtures of phenol and water at temperatures below the critical temperature ${T}_{c}$. Those experiments have been reanalyzed to evaluate the exponents $\ensuremath{\tau}$ and $\ensuremath{\theta}$ in the asymptotic expressions ${I}_{h(l)}\ensuremath{\propto}({|t|}^{\ensuremath{-}\ensuremath{\gamma}}\ifmmode\pm\else\textpm\fi{}{B}^{\ensuremath{'}}{|t|}^{\ensuremath{-}\ensuremath{\theta}})$ and ${\ensuremath{\Gamma}}_{h(l)}\ensuremath{\propto}({|t|}^{{\ensuremath{\nu}}^{*}}\ensuremath{\mp}B{|\ensuremath{\tau}|}^{\ensuremath{\tau}})$, where $I$ and $\ensuremath{\Gamma}$ are, respectively, the intensity and spectral width of the scattered light and $t=\frac{(T\ensuremath{-}{T}_{c})}{{T}_{c}}$. The experimental results are discussed in terms of recent ideas concerning expected nonsymmetric behavior in pure fluids and binary mixtures. The value of $\ensuremath{\tau}$ the experiments yield can be accounted for in terms of simple linear dependence of the viscosity on concentration.