Atmospheric coherent X‐ray diffraction imaging for in situ structural analysis at SPring‐8 Hyogo beamline BL24XU

Coherent X‐ray diffraction imaging (CXDI) is a promising technique for non‐destructive structural analysis of micrometre‐sized non‐crystalline samples at nanometre resolutions. This article describes an atmospheric CXDI system developed at SPring‐8 Hyogo beamline BL24XU for in situ structural analysis and designed for experiments at a photon energy of 8 keV. This relatively high X‐ray energy enables experiments to be conducted under ambient atmospheric conditions, which is advantageous for the visualization of samples in native states. The illumination condition with pinhole‐slit optics is optimized according to wave propagation calculations based on the Fresnel–Kirchhoff diffraction formula so that the sample is irradiated by X‐rays with a plane wavefront and high photon flux of ∼1 × 1010 photons/16 µmø(FWHM)/s. This work demonstrates the imaging performance of the atmospheric CXDI system by visualizing internal voids of sub‐micrometre‐sized colloidal gold particles at a resolution of 29.1 nm. A CXDI experiment with a single macroporous silica particle under controlled humidity was also performed by installing a home‐made humidity control device in the system. The in situ observation of changes in diffraction patterns according to humidity variation and reconstruction of projected electron‐density maps at 5.2% RH (relative humidity) and 82.6% RH at resolutions of 133 and 217 nm, respectively, were accomplished. A coherent X‐ray diffraction imaging (CXDI) system for structural analysis under atmospheric conditions has been constructed at SPring‐8 Hyogo beamline BL24XU. This article reports on the current status of the atmospheric CXDI system, including an attempt towards in situ investigation of structural changes in materials under controlled humidity.