We report observations of nanosecond nonuniform colloidal dynamics in a free flowing liquid jet using ultrafast x-ray speckle visibility spectroscopy. Utilizing a nanosecond double-bunch mode, the Linac Coherent Light Source free electron laser produced pairs of femtosecond coherent hard x-ray pulses. By exploring anisotropy in the visibility of summed speckle patterns which relates to the correlation functions, we evaluate not only the average particle flow rate in a colloidal nanoparticle jet, but also the nonuniform flow field within. The methodology presented here establishes the foundation for the study of nano- and atomic-scale inhomogeneous fluctuations in complex matter using x-ray free electron laser sources.

中文翻译：

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纳秒 X 射线散斑可见光谱法探测非均匀流动动力学

我们使用超快 X 射线散斑能见度光谱报告了自由流动液体射流中纳秒非均匀胶体动力学的观察结果。利用纳秒双束模式，直线加速器相干光源自由电子激光器产生成对的飞秒相干硬 X 射线脉冲。通过探索与相关函数相关的总散斑图案可见性的各向异性，我们不仅评估了胶体纳米粒子射流中的平均粒子流速，还评估了其中的非均匀流场。这里介绍的方法为使用 X 射线自由电子激光源研究复杂物质中的纳米和原子级不均匀波动奠定了基础。