Temperature‐Jump Experiments with a Binary Critical Mixture Near the Critical Temperature

Abstract

AbstractThe time course of turbidity of critical isobutyric acid/water mixtures is measured after perturbing the internal equilibrium of the mixture by a small temperature jump (e.g. δT ≃ 0.05 K). The experiments are carried out as function of the temperature distance from the critical temperature (0.1 K < T – Tc < 0.6 K). A mechanism for the relaxation of turbidity change is proposed having a relaxation time of the order of ζ2 D−1 with ζ = ζ0ϵ−v and D = D0ϵ−v (ζ = correlation length of concentration fluctuations, D = mutual diffusion coefficient, v = 2/3, ϵ = (T* – Tc)/Tc, T* = T + δT/2). The experimental data are in qualitative agreement with the proposed mechanism.