Critical dynamics of the binary system nitroethane/3-methylpentane: relaxation rate and scaling function.
Critical dynamics of the binary system nitroethane/3-methylpentane: relaxation rate and scaling function.
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二元系统硝基乙烷/3-甲基戊烷的临界动力学：弛豫率和标度函数。
DOI：
10.1021/jp0569584
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
U. Kaatze
中科院分区：
文献类型：
--
作者：
I. Iwanowski;K. Leluk;M. Rudowski;U. Kaatze
剪切粘度和动态光散射测量以及超声波光谱研究的硝基乙烷/3-甲基戊烷混合物的临界组成已在不同的温度附近的临界温度，T（c）。剪切粘度和互扩散系数数据的综合评价得出波动相关长度xi的振幅xi（0），假设遵循幂律，以及弛豫速率Gamma或序参数波动。发现后者遵循具有理论普适指数的幂律。振幅xi（0）= 0.23 +/- 0.02 nm和Gamma（0）=（125 +/- 5）x 10（9）s（-1）与文献值非常一致。使用从粘度和扩散系数数据产生的弛豫速率，标度函数已被计算假设的超声波光谱是由一个关键的部分和一个非关键的背景贡献。实验的标度函数很好地符合Bhattacharjee-Ferrell动态标度模型的预测，其标度半衰减频率为Omega（BF）1/2= 2.1。声波频谱的振幅产生了|G| = 0.26的绝热耦合常数g，与另一个热力学关系式的-0.29相当一致。
Shear viscosity and dynamic light scattering measurements as well as ultrasonic spectrometry studies of the nitroethane/3-methylpentane mixture of critical composition have been performed at various temperatures near the critical temperature, T(c). A combined evaluation of the shear viscosity and mutual diffusion coefficient data yielded the amplitude, xi(0), of the fluctuation correlation length, xi, assumed to follow power law, and the relaxation rate, Gamma, or order parameter fluctuations. The latter was found to follow power law with the theoretical universal exponent. The amplitudes xi(0) = 0.23 +/- 0.02 nm and Gamma(0) = (125 +/- 5) x 10(9) s(-1) nicely agree with literature values. Using the relaxation rates resulting from the viscosity and diffusion coefficient data, the scaling function has been calculated assuming the ultrasonic spectra to be composed of a critical part and a noncritical background contribution. The experimental scaling function fits well to the predictions of the Bhattacharjee-Ferrell dynamic scaling model with scaled half-attenuation frequency, Omega(BF)1/2= 2.1. The amplitude of the sonic spectra yields the amount |g| = 0.26 of the adiabatic coupling constant, g, in fair agreement with -0.29 from another thermodynamic relation.