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Yamaguchi, Akiko; Okumura, Masahiko; Takahashi, Yoshio*
SPring-8/SACLA Research Frontiers 2024 (Internet), p.86 - 87, 2025/08
Adsorption reactions on clay minerals are important reactions that affect the environmental behavior of various elements, but due to their complexity, there are still many unresolved issues. In this study, we focused on radium, which has the largest ionic radius among alkaline earth metals, and performed the world's first extended X-ray absorption fine structure (EXAFS) measurement of radium adsorbed on clay minerals to clarify the adsorption structure of radium. The results for radium were compared with those for other elements, and the stability of the adsorption structure was evaluated by first-principles calculations to clarify the determinants of the adsorption structure of clay minerals.
Yomogida, Takumi; Yamada, Shinya*; Takahashi, Yoshio*
SPring-8/SACLA Research Frontiers 2024 (Internet), p.88 - 89, 2024/08
This article explains the recent research being carried out by our group on the application of superconducting transition edge sensors (TES) to detectors for synchrotron radiation X-ray analysis. We applied a TES spectrometer as a detector for microbeam X-ray measurements to determine uranium (U) distribution at the micro-scale and its chemical species in biotite obtained from the U mine. When using a conventional semiconductor detector, the X-ray fluorescence peaks of Rb and U overlap with each other due to the shortage of energy resolution. The conventional semiconductor detector could only observe the fluorescence X-ray of Rb K
line, which is abundant in biotite, and could not accurately detect the signal of trace amounts of U. Meanwhile, the XRF peak of the U L
line was fully separated from that of the Rb K line by using TES, which indicates that TES made it possible to perform ultra-high energy resolution analysis.