Dynamics of Concentration Fluctuations Near the Critical Mixing Point of a Binary Fluid

Abstract

The decay rate $\ensuremath{\Gamma}$ of the concentration fluctuations near the critical mixing point of 3-methylpentane-nitroethane has been measured as a function of the correlation length $\ensuremath{\xi}$ and the wave number $k$ in the range $0.1<~k\ensuremath{\xi}<~20$. We have confirmed the theoretical prediction that $\ensuremath{\Gamma}$ varies as ${k}^{3}$ in the critical regime. An analysis of $\ensuremath{\Gamma}$ as a function of $k\ensuremath{\xi}$ reveals deviations from the theory of Kawasaki, which are discussed.