Nanofocused x-ray photon correlation spectroscopy

Here, we demonstrate an experimental proof of concept for nanofocused x-ray photon correlation spectroscopy, a technique sensitive to nanoscale fluctuations present in a broad range of systems. The experiment, performed at the NanoMAX beamline at MAX IV, uses a novel event-based x-ray detector to capture nanopar-ticle structural dynamics with microsecond resolution. By varying the nanobeam size from sigma = 88 nm to sigma = 2.5 mu m, we quantify the effect of the nanofocus on the small-angle scattering lineshape and on the diffusion coefficients obtained from nano-XPCS. We observe that the use of nanobeams leads to a multifold increase in speckle contrast, which greatly improves the experimental signal-to-noise ratio, quantified from the two-time intensity correlation functions. We conclude that it is possible to account for influence of the high beam divergence on the lineshape and measured dynamics by including a convolution with the nanobeam profile in the model.

Automated summary

This study demonstrates an experimental proof of concept for nanofocused x-ray photon correlation spectroscopy, using a novel event-based x-ray detector to capture nanoparticle structural dynamics with microsecond resolution. The research shows the impact of nanobeam size on small-angle scattering lineshape and diffusion coefficients obtained from nano-XPCS.