High-sensitive measurement of uranium LIII-edge X-ray absorption near-edge structure (XANES) for the determination of the oxidation states of uranium in crustal materials |
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| Authors: | Yuhei Yamamoto Yoshio Takahashi Yutaka Kanai Yoshio Watanabe Tomoya Uruga Hajime Tanida Yasuko Terada Hiroshi Shimizu |
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| Institution: | 1. Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan;2. Laboratory for Multiple Isotope Research for Astro- and Geochemical Evolution (MIRAGE), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan;3. Research Core for Deep Geological Environments, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8567, Japan;4. SPring-8, Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan |
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| Abstract: | The uranium LIII-edge XANES spectra for natural rocks at the concentration range of 0.96–124 mg kg−1 were measured using a log spiral bent crystal Laue analyzer (BCLA) combined with a multi-element Ge detector. It was found that the quality of the XANES spectra using the BCLA was greatly improved due to a reduction of interfering fluorescence from major components such as Rb and Sr. The ratio of signal to background intensities in the U LIII-edge XANES spectra increased by a factor of 2.9–17 with the use of the BCLA, which greatly enhanced the detection limit for the speciation of the oxidation states of U or the U(IV)/U(VI) ratio of natural samples. In addition, it was demonstrated that the fluorescence XANES method coupled with the BCLA enable determination of the speciation of U for various natural samples such as acidic igneous rocks, ferromanganese nodules, sediments, and some sedimentary rocks such as shale and limestone. |
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