京都大学 · 材料科学
Asakura教授の研究室では、触媒反応における遷移金属の電子状態と局所構造の動的変化を、時間分解型オペランドXASを核に、高精度な分光測定と理論計算を融合して解明しています。特に、Rh/Al₂O₃触媒における酸化還元反応のメカニズムやランタノイド酸化物の電子配置とdバンド構造の相関関係を、XANESの局所電子状態の精密解析によって明らかにしています。反応条件下での物質の動的挙動をリアルタイムで捉えることで、触媒の機能理解に貢献する革新的な分光技術の開発が進められています。
Figures are computed from collected data and may differ slightly.
The dynamic behavior of Rh species in 1 wt% Rh/Al<sub>2</sub>O<sub>3</sub> catalyst during the three-way catalytic reaction was examined using a micro gas chromatograph, a NO<sub>x</sub> meter, a quadrupole mass spectrometer, and time-resolved quick X-ray absorption spectroscopy (XAS) measurements at a public beamline for XAS, BL01B1 at SPring-8, operando. The combined data suggest different surface rearrangement behavior, random reduction processes, and autocatalytic oxidation processes of Rh s
La L1 and L3-edge X-ray absorption near-edge structure (XANES) of various La oxides were classified according to the local configuration of La. We found a correlation between both of the areas of the pre-edge peaks of the La L1-edge XANES spectra and the full width at half-maximum of white line of La L3-edge XANES spectra and the local configuration of La. Theoretical calculation of the XANES spectra and local density of states reveals the difference of La L1 and L3-edge XANES spectra of various
The characteristics of K-, L1-, and L3-edges of XANES (X-ray Absorption Near Edge Structure) spectra of group V, VI, and VII compounds, which have different coordination number, number of d electrons, and the coordination sphere symmetry, have been classified. Two p → d transitions were observed in the second derivative plots of the L3-edge XANES spectra for the group V, VI, and VII compounds. These two transitions can be assigned to split d orbitals. The splitting and area of the two white line
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