Mirzaev S Z, Behrends R, Heimburg T, Haller J, Kaatze U
Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
J Chem Phys. 2006 Apr 14;124(14):144517. doi: 10.1063/1.2188396.
The specific heat C(p) at constant pressure, the shear viscosity eta(s), and the mutual diffusion coefficient D of the 2,6-dimethylpyridine-water mixture of critical composition have been measured in the homogeneous phase at various temperatures near the lower critical demixing temperature T(c). The amplitude of the fluctuation correlation length xi(0)=(0.198+/-0.004) nm has been derived from a combined evaluation of the eta(s) and D data. This value is in reasonable agreement with the one obtained from the amplitude A(+)=(0.26+/-0.01) J(g K) of the critical term in the specific heat, using the two-scale-factor universality relation. Within the limits of error the relaxation rate Gamma of order parameter fluctuations follows power law with the theoretical universal exponent and with the amplitude Gamma=(25+/-1)x10(9) s(-1). No indications of interferences of the critical fluctuations with other elementary chemical reactions have been found. A noteworthy result is the agreement of the background viscosity eta(b), resulting from the treatment of eta(s) and D data, with the viscosity eta(s)(nu=0) extrapolated from high-frequency viscosity data. The latter have been measured in the frequency range of 5-130 MHz using a novel shear impedance spectrometer.
在接近下临界 demixing 温度 T(c) 的不同温度下，对临界组成的 2,6 - 二甲基吡啶 - 水混合物在均相中的恒压比热 C(p)、剪切粘度 eta(s) 和互扩散系数 D 进行了测量。通过对 eta(s) 和 D 数据的综合评估，得出了涨落关联长度 xi(0)=(0.198±0.004) nm 的幅度。使用双标度因子普适关系，该值与从比热临界项的幅度 A(+)=(0.26±0.01) J/(g K) 获得的值合理一致。在误差范围内，序参量涨落的弛豫率 Gamma 遵循幂律，具有理论普适指数，幅度为 Gamma=(25±1)×10(9) s(-1)。未发现临界涨落与其他基本化学反应相互干扰的迹象。一个值得注意的结果是，对 eta(s) 和 D 数据处理得到的背景粘度 eta(b) 与从高频粘度数据外推得到的粘度 eta(s)(nu = 0) 一致。后者是使用新型剪切阻抗光谱仪在 5 - 130 MHz 的频率范围内测量的。
