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

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.Comment: 45 pages, 11 figure

Structural properties of π-π conjugated network in polymer thin films studied by x-ray cross-correlation analysis

We present results of an x-ray study of structural properties of π-π conjugated networks in semicrystalline polymer thin films using nanofocused x-ray beam. We applied the x-ray cross-correlation analysis to x-ray scattering data from blends of poly(3-hexylthiophene) (P3HT) with gold nanoparticles. The Fourier spectra of the intensity cross-correlation functions for different films contain non-zero components of orders n = 2,4 and 6 revealing structural order in the system. The results suggest inhomogeneous structure of both samples, with preferential edge-on orientation of domains in one sample and mixed orientation in another sample

Software Platform for European XFEL: Towards Online Experimental Data Analysis

Large amount of data being generated at large scale facilities like European X-ray Free-Electron Laser (XFEL) requires new approaches for data processing and analysis. One of the mostcomputationally challenging experiments at an XFEL is single-particle structure determination.In this paper we propose a new design for an integrated software platform which combines well establishedtechniques for XFEL data analysis with High Performance Data Analysis (HPDA)methods. In our software platform we use streaming data analysis algorithms with high performancecomputing solutions. This approach should allow analysis of the experimental dataflow in quasionlineregime