Nonuniform Flow Dynamics Probed by Nanosecond X-Ray Speckle Visibility Spectroscopy

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.

Automated summary

Observations of nanosecond nonuniform colloidal dynamics in a free flowing liquid jet were reported using ultrafast x-ray speckle visibility spectroscopy. The study utilized a double-bunch mode to produce femtosecond coherent x-ray pulses and evaluated the average particle flow rate and nonuniform flow field within the colloidal nanoparticle jet by exploring anisotropy in speckle patterns. This methodology establishes a foundation for studying nano- and atomic-scale inhomogeneous fluctuations in complex matter using x-ray free electron laser sources.