X-ray cross-correlation analysis applied to disordered two-dimensional systems

TL;DR

This paper validates the use of angular x-ray cross-correlation analysis (XCCA) for studying disordered 2D systems through simulations, revealing how structural information depends on disorder and coherence, and demonstrating its potential in analyzing complex materials.

Contribution

The paper provides simulation-based validation of XCCA for disordered 2D systems, exploring the effects of disorder density, coherence, and averaging on structural analysis.

Findings

XCCA relates Fourier components of CCFs to system correlations

Structural information depends on disorder density and cluster orientation

Partial coherence affects the accuracy of XCCA results

Abstract

Angular x-ray cross-correlation analysis (XCCA) is an approach to study the structure of disordered systems using the results of coherent x-ray scattering experiments. Here, we present the results of simulations that validate our theoretical findings for XCCA obtained in a previous paper [M. Altarelli et al., Phys. Rev. B 82, 104207 (2010)]. We consider as a model two-dimensional (2D) disordered systems composed of non-interacting colloidal clusters with fivefold symmetry and with orientational and positional disorder. We simulate a coherent x-ray scattering in the far field from such disordered systems and perform the angular cross-correlation analysis of calculated diffraction data. The results of our simulations show the relation between the Fourier series representation of the cross-correlation functions (CCFs) and different types of correlations in disordered systems. The dependence of structural information extracted by XCCA on the density of disordered systems and the degree of orientational disorder of clusters is investigated. The statistical nature of the fluctuations of the CCFs in the model `single-shot' experiments is demonstrated and the potential of extracting structural information from the analysis of CCFs averaged over a set of diffraction patterns is discussed. We also demonstrate the effect of partial coherence of x-rays on the results of XCCA.