| Co-Investigator(Kenkyū-buntansha) |
TAGUCHI Takeyoshi Rigaku Corporation, X-ray Diffraction Business Section, Product Development Center, Vice-Councilor, X線回折事業部・商品開発センター, 副参事(研究職)
AIKA Ken-ichi Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Professor, 大学院・総合理工学研究科, 教授 (20016736)
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| Research Abstract |
X-ray absorption fine structure (XAFS) has become popular because it is applicable to noncrystalline and hybrid material and gives local structure and electronic state. In this research, we tried to solve a problem that XAFS gives average information. Head investigator has been developed site-selective XAFS spectroscopy. The aim of this study is to improve the fluorescence detection system in use of general purpose.
In the measurement of fluorescence spectrum, receiving angle of X-ray fluorescence from sample is directly related to energy resolution. In this research, horizontal Rowland-type spectrometer was produced to minimize the photon loss when the receiving angle was made smaller. Johansson-type Ge(111) and Ge(331) crystals as large as 50 × 50 mm^2 were introduced. A fully-automatic control PC software was written to easily move the position of sample, slits, crystal and the size of slits.
The spectrometer was applied to site-selective XAFS measurements for trace amounts of lead, a
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rsenic, and vanadium. The ultimate purpose of XAFS utilizing fluorescence spectrometer equipped with crystal is valence-selective XAFS measurement, but this method is also applicable to measure the absorption edge of trace amounts of element, especially in the samples that contain high concentration of heavy element(s) because a signal was detected in high energy resolution 【approximately equal】 0.1 eV. In the viewpoint of use in general purpose, adsorbents of poisonous trace amounts of elements and catalyst to decompose nitrogen oxides gas were chosen in relation to current social problems. By this study, the adsorption mechanism from 50 - 100 ppb lead or arsenic was clarified on the adsorbents. Also, the processes were clarified that the atomically-dispersed vanadates on titanium oxide surface in ambient air or in vacuum polymerize in the presence of moisture and adsorb i-propanol dissociatively. In future study, valence-selective XAFS of V^III, V^V, As^III, and As^V in the process of adsorption or catalysis will be measured. Less
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