Multiple-scattering effects in SAXS and XPCS measurements in the ultra-small-angle region

Abstract

An experimental study of the influence of multiple‐scattering events on data acquired by small‐angle X‐ray scattering (SAXS) and X‐ray photon correlation spectroscopy (XPCS) techniques in the ultra‐small‐angle range is presented. Both techniques rely on the single‐scattering assumption and any deviation may lead to erroneous interpretation of structural and dynamical results. Typical effects of multiple scattering on measured static and dynamic scattering from model colloidal suspensions are presented, and it is demonstrated that the same information content as in a single‐scattering experiment can be extracted after applying appropriate corrections. The perturbations induced by multiple scattering on resolution, photon statistics and speckle visibility are evaluated and the required optimal experimental conditions are discussed. In many cases, multiple scattering might be tolerable to a certain extent, especially if any shortcomings are outweighed by beneficial effects from counting statistics, acquisition time and signal‐to‐background ratio. The presented study may help to optimize future experiments and serve as a guide for data evaluation for this type of system.

A multipurpose instrument for time-resolved ultra-small-angle and coherent X-ray scattering

“…The inset shows the data after normalization by this factor. this case is due to multiple scattering (Semeraro, Mö ller & Narayanan, 2018) and not a resolution effect. The vertical shifts in intensities manifest the differences in the detection sensitivity, i.e.…”

Performance of the time-resolved ultra-small-angle X-ray scattering beamline with the Extremely Brilliant Source

“…However, for larger polystyrene (PS) particles (Polysciences Inc.) with R s ' 1012 nm and a narrow size distribution, polydispersity ' 0.4%, the resolution effect is manifested by the pronounced smearing of the minima in the lower-q region. For particles with a narrow size distribution, the smearing due to instrument resolution dominates at low q in the absence of multiple scattering (Semeraro et al, 2018), while the polydispersity influences the most at high q, smoothing the oscillations. Therefore, this smearing effect can be used to estimate an average Áq from the required convolution of the polydisperse sphere scattering function to describe the profile.…”

Automatic indexing of two-dimensional patterns in reciprocal space

“…In indexing LEED data, a special challenge arises due to multiple scattering [30,46] which occurs much less frequently in GIXD [47]. This can be rationalized by the much lower scattering cross section of x rays as compared to electrons [48]. If the reciprocal vector g has components of both the adsorbate and the substrate, it can be written as follows:…”