X-ray Absorption Fine Structure at the Cesium L3 Absorption Edge for Cesium Sorbed in Clay Minerals

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• 作者：Mitsunori Honda ; Iwao Shimoyama ; Yoshihiro Okamoto ; Yuji Baba ; Shinichi Suzuki ; Tsuyoshi Yaita
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：March 17, 2016
• 年：2016
• 卷：120
• 期：10
• 页码：5534-5538
• 全文大小：298K
• ISSN：1932-7455

文摘

We present the use of near-edge X-ray absorption fine structure (NEXAFS) to investigate local electronic structures of cesium ions sorbed in two types of clay minerals (vermiculite and kaolinite) with a different capacity to fix Cs. NEXAFS is element-specific because X-ray absorption edges of different elements have different energies. However, the energy of the Cs L₃ absorption edge is close to that of the K-edge of titanium generally contained in clay minerals. Therefore, Cs L₃-edge NEXAFS measurements of Cs in clay minerals have not yet succeeded. In this study, we confirmed the peak intensity between vermiculite and kaolinite in the Cs L₃-edge NEXAFS spectra by separately monitoring T Kα and Cs Lα fluorescence X-rays. To clarify the identification of NEXAFS spectra, theoretical calculations were performed using the discrete variational Xα molecular orbital method (DV-Xα), and peak identification was achieved. The difference in peak intensity was explained by the difference in the electron density of unoccupied molecular orbitals. We studied the influence of water molecules and found a change in the electron densities of unoccupied molecular orbitals caused by the coordination of water molecules.