The advent of high-speed x-ray photon correlation spectroscopy now allows the study of critical phenomena in fluids to much smaller length scales and over a wider range of temperatures than is possible with dynamic light scattering. We present an x-ray photon correlation spectroscopy study of critical fluctuation dynamics in a complex fluid typical of those used in liquid-liquid extraction (LLE) of ions, dodecane-DMDBTDMA with extracted aqueous $\mathrm{Ce}({\mathrm{NO}}_3{)}_3$. We observe good agreement with both static and dynamic scaling without the need for significant noncritical background corrections. Critical exponents agree with 3D Ising values, and the fluctuation dynamics are described by simple exponential relaxation. The form of the dynamic master curve deviates somewhat from the Kawasaki result, with a more abrupt transition between the critical and noncritical asymptotic behavior. The concepts of critical phenomena thus provide a quantitative framework for understanding the structure and dynamics of LLE systems and a path forward to new LLE processes.

中文翻译：

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X射线光子相关光谱研究复杂流体中的纳米临界现象

高速X射线光子相关光谱的出现现在允许研究流体中的临界现象，而这种现象比动态光散射要小得多，而且尺度更小，温度范围更广。我们提供了一种X射线光子相关光谱学，研究了复杂流体中的临界波动动力学，这些流体典型用于离子液-液萃取（LLE），十二烷-DMDBTDMA和萃取液$策（{\mathrm{没有}}_3{）}_3$。我们观察到静态和动态缩放具有良好的一致性，而无需进行重大的非关键背景校正。关键指数与3D Ising值一致，并且波动动力学通过简单的指数松弛来描述。动态主曲线的形式与Kawasaki结果略有不同，临界和非临界渐近行为之间的过渡更加突然。因此，关键现象的概念为理解LLE系统的结构和动力学提供了一个定量框架，并为通往新的LLE过程提供了一条途径。