Small-angle X-ray scattering in the era of fourth-generation light sources

J Appl Crystallogr. 2023 Jun 23;56(Pt 4):939-946. doi: 10.1107/S1600576723004971. eCollection 2023 Aug 1.

Abstract

Recently, fourth-generation synchrotron sources with several orders of magnitude higher brightness and higher degree of coherence compared with third-generation sources have come into operation. These new X-ray sources offer exciting opportunities for the investigation of soft matter and biological specimens by small-angle X-ray scattering (SAXS) and related scattering methods. The improved beam properties together with the advanced pixel array detectors readily enhance the angular resolution of SAXS and ultra-small-angle X-ray scattering in the pinhole collimation. The high degree of coherence is a major boost for the X-ray photon correlation spectroscopy (XPCS) technique, enabling the equilibrium dynamics to be probed over broader time and length scales. This article presents some representative examples illustrating the performance of SAXS and XPCS with the Extremely Brilliant Source at the European Synchrotron Radiation Facility. The rapid onset of radiation damage is a significant challenge with the vast majority of samples, and appropriate protocols need to be adopted for circumventing this problem.

Keywords: X-ray photon correlation spectroscopy; active colloids; fourth-generation synchrotrons; radiation damage; small-angle X-ray scattering; soft matter systems; ultra-small-angle X-ray scattering.

Grants and funding

The ESRF is gratefully acknowledged for the financial support and provision of synchrotron beam time.