When coherent light illuminates a material with spatial inhomogeneities, one observes a speckle pattern in the far-field diffraction plane of the sample. If the state of disorder of the sample changes in time, for example by Brownian motion, the speckle pattern will change and its time variations can be used to measure the sample diffusion constant. This talk will review the development of coherent diffraction experiments at advanced X-ray light sources such as the Advanced Photon Sources and show some recent results such as those shown in the links below.
https://www.aps.anl.gov/APS-Science-Highlight/2018/gel-formation-revealed
https://www.aps.anl.gov/APS-Science-Highlight/2017/creeping-of-striped-nanodomains-in-nominal-atomic-layers-of
http://www.anl.gov/articles/x-ray-imaging-and-computer-modeling-help-map-electric-properties-nanomaterials