From Femtoseconds to Hours: Dynamics over 18 Orders of Magnitude

XPCS scheme.

In this publication we review the recent development of probing dynamics by X-ray photon correlation spectroscopy (XPCS) and X-ray speckle visibility spectroscopy (XSVS). As coherent scattering techniques, both benefit from the increased brilliance of the next-generation synchrotron radiation and Free-Electron Laser (FEL) sources. In this article, we introduce the XPCS and XSVS concepts and review the latest developments with special attention on the extension of accessible time scales to sub-μs and the application of XPCS at FELs. Furthermore, we will discuss future opportunities at new X-ray sources. Due to its particular signal-to-noise ratio, the time scales accessible by XPCS scale with the square of the coherent flux, allowing to dramatically extend its applications. This will soon enable studies over more than 18 orders of magnitude in time by XPCS and XSVS.

Applied Sciences 11, 6179 (2021)