Takeya Satoshi, Muromachi Sanehiro, Hachikubo Akihiro, Ohmura Ryo, Hyodo Kazuyuki, Yoneyama Akio
National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan.
Phys Chem Chem Phys. 2020 Dec 16;22(47):27658-27665. doi: 10.1039/d0cp05466f.
In this study, X-ray imaging of inclusion compounds encapsulating various guest species was investigated based on the calculation of X-ray attenuation coefficients. The optimal photon energies of clathrate hydrates were simulated for high-contrast X-ray imaging based on the type of guest species. The proof of concept was provided by observations of Kr hydrate and tetra-n-butylammonium bromide (TBAB) semi-clathrate hydrate using absorption-contrast X-ray computed tomography (CT) and radiography with monochromated synchrotron X-rays. The radiographic image of the Kr hydrate also revealed a sudden change in its attenuation coefficient owing to the K-absorption edge of Kr as the guest element. With a photon energy of 35 keV, X-ray CT provided sufficient segmentation for the TBAB semi-clathrate hydrate coexisting with ice. In contrast, the simulation did not achieve the sufficient segmentation of the CH4 and CO2 hydrates coexisting with water or ice, but it revealed the capability of absorption-contrast X-ray CT to model the physical properties of clathrate hydrates, such as Ar and Cl2 hydrates. These results demonstrate that the proposed method can be used to investigate the spatial distribution of specific elements within inclusion compounds or porous materials.
在本研究中，基于X射线衰减系数的计算，对包封各种客体物种的包合物进行了X射线成像研究。根据客体物种的类型，模拟了笼形水合物用于高对比度X射线成像的最佳光子能量。通过使用吸收对比X射线计算机断层扫描（CT）和单色同步加速器X射线进行射线照相，对氪水合物和四正丁基溴化铵（TBAB）半笼形水合物进行观察，提供了概念验证。氪水合物的射线照相图像还显示，由于作为客体元素的氪的K吸收边，其衰减系数发生了突然变化。在35keV的光子能量下，X射线CT为与冰共存的TBAB半笼形水合物提供了足够的分割。相比之下，模拟未能对与水或冰共存的CH4和CO2水合物进行充分分割，但它揭示了吸收对比X射线CT对笼形水合物物理性质（如Ar和Cl2水合物）进行建模的能力。这些结果表明，所提出的方法可用于研究包合物或多孔材料中特定元素的空间分布。
