Internal structure in small Au crystals resolved by three-dimensional inversion of coherent x-ray diffraction

Coherent x-ray diffraction CXD is a technique which utilizes the favorable coherence properties of an x-ray beam to collect three-dimensional 3D diffraction data from which the 3D shape of a sample can be determined. The shape of the sample is found by reconstructing the phase of the diffracted wave in the far field using iterative techniques and recognizing the relationship between this complex amplitude and the sample’s electron density. We describe the experimental procedure for measuring CXD near a high-angle Bragg peak from a small crystal and report the 3D shape information recovered by overcoming the so-called phase problem. We also describe the reconstruction procedure, including some difficulties encountered therein and the steps taken to ameliorate these problems. In the final reconstruction of the electron density we observe nanometer-scale density variation within the crystal that we attribute to deformation.