Symmetry dependence of x-ray absorption near-edge structure at the metal K edge of 3d transition metal compounds
| Autor: | D. C. Xian, C. R. Natoli, Augusto Marcelli, Annibale Mottana, Eleonora Paris, Z. Wu |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Applied Physics Letters. 79:1918-1920 |
| ISSN: | 1077-3118 0003-6951 |
| Popis: | The pre-edge features in a system with "even" symmetry, apart from quadrupolar transition contribution, are mainly dipolar in character, associated with the existence of unoccupied states made up of mixed cation np with higher-neighboring cation- (n-1) d orbitals, and reflect the density of states due to the medium-range order of the system, while in "odd" symmetry materials these pre-edge features are the result of a transition from the Is to a final density of states of p symmetry due to an unsymmetrical mixing of the ligand wave functions with the central cation d orbitals. In the latter case, they contain not only the p but also the d base of orbitals, similar to a tetrahedral configuration. These results are validated for Fe as a photoabsorber by comparing x-ray absorption near-edge spectra of Fe2SiO4 (fayalite) and Fe2O3 (hematite) to ab initio full multiple scattering calculations at the Fe K edge, but pertain to all systems containing sixfold-coordinated cations. (C) 2001 American Institute of Physics. |
| Databáze: | OpenAIRE |
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