Automated Laue pattern analysis for multi-grain strain imaging of nanocrystals at 34-ID-C*

The 34-ID-C beamline of the Advanced Photon Source recently acquired the capability to conduct Laue diffraction for indexing arbitrarily oriented nanocrystals [1], thus, facilitating the collection of Bragg coherent diffraction imaging (BCDI) data from multiple Bragg reflections and reconstructing the volumetric six-component Eulerian strain tensor [2]. A polychromatic (pink) x-ray beam illuminates a single nanocrystal, or cluster of crystals, causing multiple reflections to simultaneously fulfill the Bragg condition casting a unique Laue pattern on a pixel array. When many grains are simultaneously illuminated, multiple Laue patterns appear on the detector and must be separately indexed. We developed a workflow for beamline users that automates the analysis of overlapping Laue patterns. We demonstrate our algorithms with synthetic data and verify them by comparing the result of indexing Laue patterns recorded from a patch of arbitrarily oriented gold nanocrystals with the results from electron back-scattering diffraction. Such tools will provide reliable indexing of grains of polycrystalline materials and allow us to probe embedded grains with BCDI experiments, at a scale that is challenging for other techniques.

 

[1] Pateras, et al. J. Synchrotron Radiat. 27, 1430 (2020).

[2] Wilkin et al. Phys. Rev. B 103, 214103 (2021)