Dynamics and rheology under continuous shear flow studied by x-ray photon correlation spectroscopy
Dynamics and rheology under continuous shear flow studied by x-ray photon correlation spectroscopy
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DOI：
10.1088/1367-2630/12/3/035023
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发表时间：
2010-03-31
影响因子：
3.3
通讯作者：
Madsen, Anders
中科院分区：
文献类型：
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作者：
Fluerasu, Andrei;Kwasniewski, Pawel;Madsen, Anders
x射线光子相关光谱学（XPCS）是一种独特的技术，可以在介观长度尺度上测量材料的动力学。与使用明亮x射线光束相关的最常见问题之一是光束引起的辐射损伤，这可能成为未来同步加速器和自由电子激光源的一个更大的限制因素。在数据采集过程中流动样品是限制辐射损伤的最简单方法之一。除了在许多不同的散射体上分配剂量外，该方法还具有新的功能，例如时间分辨研究。在这里，我们进一步发展了最近提出的结合XPCS和连续流动样品的实验技术。更具体地说，我们使用一个胶体悬浮液模型来展示如何从x射线数据中量化宏观对流响应和微观耗散动力学（扩散）。结果表明，该模型与泊塞维尔流体力学模型和布朗力学模型在定量上有很好的一致性。该方法具有许多潜在的应用，例如研究玻璃和凝胶在连续剪切/流动下的动力学，蛋白质聚集过程以及复杂流体中动力学与流变学之间的相互作用。
X-ray photon correlation spectroscopy (XPCS) has emerged as a unique technique allowing the measurement of dynamics of materials on mesoscopic lengthscales. One of the most common problems associated with the use of bright x-ray beams is beam-induced radiation damage, and this is likely to become an even more limiting factor at future synchrotron and free-electron laser sources. Flowing the sample during data acquisition is one of the simplest methods allowing the radiation damage to be limited. In addition to distributing the dose over many different scatterers, the method also enables new functionalities such as time-resolved studies. Here, we further develop a recently proposed experimental technique that combines XPCS and continuously flowing samples. More specifically, we use a model colloidal suspension to show how the macroscopic advective response to flow and the microscopic dissipative dynamics (diffusion) can be quantified from the x-ray data. Our results show very good quantitative agreement with a Poisseuille-flow hydrodynamical model combined with Brownian mechanics. The method has many potential applications, e. g. in the study of dynamics of glasses and gels under continuous shear/flow, protein aggregation processes and the interplay between dynamics and rheology in complex fluids.