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固溶体・溶液の溶存化学種の化学結合のXANESスペクトルによる研究

使用 XANES 光谱研究固溶体和溶液中溶解化学物质的化学键

基本信息

批准号：
10640544
负责人：
NAKAMATSU Hirohide
金额：
$ 2.05万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640544/
关键词：
XANES crystal first-principles molecular orbital method continuum state local structure chemical state

项目摘要

XANES (X-ray Absorption Near-Edge Structure) is sensitive to chemical states and local structures around photoexcited atoms in materials. We have obtained theoretical spectra by first-principles DV-Xα molecular orbital method with continuum basis functions in the frame work of the LィイD12ィエD1 method. Some developments and improvements of the software were performed in the present work. A number of basis functions were utilized for two steps of the continuum calculations. First, an extended basis set consisting of continuum wave functions and a minimal set of atomic orbital were used to obtain self-consistent charge density. Then a further extended basis set was used to represent the states in the continuum. The obtained wave functions were also utilized for understanding characters of the peaks in XANES.Most of the conclusions drawn from the XANES for the lanthanoid compounds were concerned with the chemical states and characteristics of the electronic structures. Theoretical XANES spectra for CeOィイD22ィエD2 and vacancy-including CeOィイD22ィエD2 ・LaィイD22ィエD2OィイD23ィエD2 solid solution were obtained in the present work. Peaks in the Ce LィイD23ィエD2 X-ray absorption spectra were assigned to quasi-bound states which were generated by the cage effect due to the oxygen atoms surrounding the Ce atom. A spectral change originating from the oxygen vacancy of the solid solution was analyzed. It is found that valence fluctuation of Ce, possibly caused by the vacancy formation, is undistinguishable in the spectra. Theoretical and experimental spectra of the sulfur K absorption for SOィイD24ィエD2ィイD12-ィエD1 and SOィイD23ィエD2ィイD12-ィエD1 ions are compared. The peaks in the spectra are assigned to atomic pairs of scattering such as S-O and S-Na for NaィイD22ィエD2SOィイD24ィエD2. Theoretical XANES of Li compounds revealed characters of each peak in the spectra. Charge transfer from the Li ion to the halogen ions due to exciton and scattering between Li-halogen were clarified.

XANES（X射线吸收近边结构）对材料中光激发原子周围的化学状态和局部结构敏感。我们在LイD12 D1方法的框架下，采用连续基函数的第一性原理DV-Xα分子轨道方法获得了理论光谱。在目前的工作中，软件的一些发展和改进。一些基函数被用于连续计算的两个步骤。首先，采用由连续波函数组成的扩展基组和原子轨道的最小集合来获得自洽的电荷密度。然后用进一步扩展的基组来表示连续统中的状态。利用所得到的波函数对XANES谱峰的性质进行了研究，得到的结论大多与镧系元素的化学状态和电子结构特征有关。获得了CeO_（22）La_（23）D_2和含空位的CeO_（22）La_（23）D_2固溶体的理论XANES谱。Ce L_（23）Ce_（23）Ce_（23）D_2的X射线吸收谱中的峰归属于由于Ce原子周围的氧原子的笼效应而产生的准束缚态。分析了由固溶体的氧空位引起的光谱变化。结果表明，Ce的价态起伏在谱图上很难分辨，这可能是由于空位的形成引起的。本文比较了SO_（24）O_（23）O_（24）D_（2）O_（12）-O_（24）D_（12）-O_（24）D_（24）和SO_（23）O_（23）D_（24）D_（12）-O_（24）D_（12）-O_（24）D_（12）的硫K吸收光谱的理论和实验结果。光谱中的峰被指定为散射的原子对，例如Na D22 D2 SO D24 D2的S-O和S-Na。Li化合物的理论XANES谱揭示了谱中各峰的特征。由于激子和锂-卤素之间的散射，从锂离子到卤素离子的电荷转移被澄清。