Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0855, Japan.
RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo 679-5148, Japan.
J Synchrotron Radiat. 2020 Mar 1;27(Pt 2):455-461. doi: 10.1107/S1600577519017004. Epub 2020 Jan 29.
This work demonstrates a combination technique of X-ray ptychography and the extended X-ray absorption fine structure (ptychography-EXAFS) method, which can determine the interatomic distances of bulk materials at the nanoscale. In the high-resolution ptychography-EXAFS method, it is necessary to use high-intense coherent X-rays with a uniform wavefront in a wide energy range, hence a ptychographic measurement system installed with advanced Kirkpatrick-Baez mirror focusing optics is developed and its performance is evaluated. Ptychographic diffraction patterns of micrometre-size MnO particles are collected by using this system at 139 energies between 6.504 keV and 7.114 keV including the Mn K absorption edge, and then the EXAFS of MnO is derived from the reconstructed images. By analyzing the EXAFS spectra obtained from a 48 nm × 48 nm region, the nanoscale bond lengths of the first and second coordination shells of MnO are determined. The present approach has great potential to elucidate the unclarified relationship among the morphology, electronic state and atomic arrangement of inhomogeneous bulk materials with high spatial resolution.
这项工作展示了一种 X 射线叠层术和扩展 X 射线吸收精细结构（叠层术-EXAFS）方法的组合技术，可用于确定纳米尺度下块状材料的原子间距离。在高分辨率叠层术-EXAFS 方法中，需要使用高强度、波前均匀的宽能区相干 X 射线，因此开发并评估了一种配备先进的 Kirkpatrick-Baez 镜聚焦光学器件的叠层术测量系统。利用该系统在包括 Mn K 吸收边在内的 6.504 keV 至 7.114 keV 之间的 139 个能量点上采集了微米级 MnO 颗粒的叠层术衍射图样，然后从重构图像中得出 MnO 的 EXAFS。通过分析从 48nm×48nm 区域获得的 EXAFS 光谱，确定了 MnO 的第一和第二配体壳层的纳米级键长。该方法具有阐明具有高空间分辨率的非均匀块状材料的形貌、电子态和原子排列之间不明确关系的巨大潜力。
