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

Abstract

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