For the first time, we demonstrate that it is possible to simultaneously analyze microscopic fluctuations at the surface and in the bulk of a binary liquid mixture by dynamic light scattering in macroscopic thermodynamic equilibrium. For a model system containing n-octacosane and ethanol, three individual signals distinguishable in the time-resolved analysis of the scattered light intensity appear on different time scales. One oscillatory signal from surface fluctuations at the vapor–liquid interface in the short-time range and two exponential Rayleigh signals from fluctuations in temperature and concentration in the bulk of fluid in the long-time range could be associated with hydrodynamic modes. This microscopic information allows for a simultaneous determination of the macroscopic properties interfacial tension, kinematic viscosity, thermal diffusivity, and mutual diffusivity within a single experimental run. The presented approach represents a worthwhile strategy, for example, in the context of sensor development for an effective multiproperty determination of fluid systems.

中文翻译：

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动态光散射同时分析二元液体混合物表面和本体的平衡涨落

第一次，我们证明可以通过宏观热力学平衡中的动态光散射同时分析二元液体混合物的表面和大部分的微观波动。对于包含n的模型系统-十八碳烷和乙醇，在散射光强度的时间分辨分析中可区分的三个独立信号出现在不同的时间尺度上。在短时间范围内，气液界面处的表面起伏产生的一个振荡信号，在长时间范围内，来自流体的温度和浓度的起伏产生的两个指数瑞利信号可能与流体动力学模式有关。该微观信息允许在单个实验运行中同时确定宏观性质，界面张力，运动粘度，热扩散率和相互扩散率。所提出的方法代表了一种有价值的策略，例如，在传感器开发的背景下，可以对流体系统进行有效的多属性确定。