Electronic and Chemical State of Aluminum from the Single- (K) and Double-Electron Excitation (KLII&III, KLI) X-ray Absorption Near-Edge Spectra of 伪-Alumina, Sodium Aluminate, A

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• 作者：John L. Fulton ; Niranjan Govind ; Thomas Huthwelker ; Eric J. Bylaska ; Aleksei Vjunov ; Sonia Pin ; Tricia D. Smurthwaite
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：119
• 期：26
• 页码：8380-8388
• 全文大小：467K
• ISSN：1520-5207

文摘

We probe, at high energy resolution, the double electron excitation (KL_II&II) X-ray absorption region that lies approximately 115 eV above the main Al K-edge (1566 eV) of 伪-alumina and sodium aluminate. The two solid standards, 伪-alumina (octahedral) and sodium aluminate (tetrahedral), are compared to aqueous species that have the same Al coordination symmetries, Al³⁺路6H₂O (octahedral) and Al(OH)₄^{鈥?/sup> (tetrahedral). For the octahedral species, the edge height of the KL_II&III-edge is approximately 10% of the main K-edge; however, the edge height is much weaker (3% of K-edge height) for Al species with tetrahedral symmetry. For the 伪-alumina and aqueous Al3+路6H₂O the KL_II&III spectra contain white line features and extended absorption fine structure (EXAFS) that mimics the K-edge spectra. The KL_II&III-edge feature interferes with an important region in the EXAFS spectra of the crystalline and aqueous standards. The K-edge spectra and K-edge energy positions are predicted using time-dependent density functional theory (TDDFT). The TDDFT calculations for the K-edge X-ray absorption near-edge spectra (XANES) reproduce the observed transitions in the experimental spectra of the four Al species. The KL_II&II and KL_I onsets and their corresponding chemical shifts for the four standards are estimated using the delta self-consistent field (螖SCF) method.}