Symmetry role on the preedge X—ray absorption fine structure at the metal K edge |
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作者姓名: | ZiyuWu C.R.Natoli A.Marcelli E.Paris F.Seifert J.Zhang TLiu |
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作者单位: | [1]BayerischesGeoinstitut,UniversitatBayreuth,D-95440Bayreuth,Germany [2]BeijingSynchrotronRadiationFacility,InstituteofHighEnergyPhysics,ChineseAcademyofSciences,P.O.Box918,Beijing100039,P.R.China [3]Dipartim,InstituteofHighEnergyPhysics,ChineseAcademyofSciences,P.O.Box918,Beijing100039,P.R.China |
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摘 要: | The preedge 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-4p with higher-neighboring cation-3d orbitals,and reflect the density of states due to the medium-range order of the system.In “odd“symmetry materials these preedge features ate the result of a transition from the ls to a final density of states of p symmetry due to an unsymmetrical mixing of the ligand wave functions with the central cation 3d orbitals,similar to atetrahedral configuration.These results are validated for Fe as a photoabsorber by comparing XAS spectra of Fe2SiO4(fayalite) to ab initio full multiple scattering calculations at the fe K edge,but pertain to all systems containing sixfold-coordinated cations.
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关 键 词: | X射线吸收精细结构 EXAFS 对称性 钾金属 X—射线近边吸收谱 |
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