表面分析の手段として知られる角度分解光電子分光の計算機シミュレーションの手法とその最近の応用例を紹介する。角度分解光電子分光はバンド計算と直接比較するのは定量的にはふさわしくなく, スペクトルそのものの計算が必要である。また, 表面に敏感なので, バルクのバンドを測るときも表面の構造を考えて分析する必要がある。

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A new approach to XANES calculation is proposed and applied to Si and Fe K-edge XANES spectra to study the efficiency of this method. This method based on the partitioning technique includes important multiple scatterings in infinite order, but excludes unimportant multiple scatterings. The result of calculation for Si 35atom cluster shows that even if we include up to 7th multiple scatterings in the partial sum, the computation time is about 5% of that needed for the full multiple scattering calculation, and a good convergence to the full multiple scattering result is found. Similar result is obtained for iron clusters. The present study demonstrates the high efficiency and accuracy of this new method.

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We evaluated structural stabilities for A-site-ordered perovskites using the computer program "SPuDS", and succeeded in synthesizing designed AMn₃Al₄O₁₂ (A=Y, Dy) under high-pressure and high-temperature conditions. Bond Valence Sum calculations with the refined structural parameters revealed that the compounds are represented as ionic A³⁺Mn³⁺₃Al³⁺₄O^2-₁₂. Mn³⁺ ions at the A' site produce high-spin magnetic moments and they align antiferromagnetically. The A-site Dy spins, on the other hand, behave paramagnetically and show no correlation with the A'-site Mn spins. The antiferromagnetism of the A'-site Mn spins is caused by the nearest neighboring Mn-Mn direct exchange interaction.

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Evaluation of the elastic scattering effect in electron spectroscopies, i.e. XPS, AES, EPES etc., is important for the quantitative surface analysis. We classify the elastic scattering effects and emphasize the importance of a choice of the elastic-scattering differential-cross-sections based on Rutherford scattering, Thomas-Fermi-Dirac potential, and Dirac-Hartree-Fock potential for the detailed estimation of the elastic scattering effects. We also mention of the simple way to deal with the average practical effective attenuation length (average PEAL) including elastic scattering effects and demonstrate this average PEAL is useful for the analysis of angle-resolved high-energy XPS.

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