在LaO1-xFxFeAs系统上进行X射线吸收光谱测量
X-ray absorption spectroscopy measurement on the LaO1-xFxFeAs system
摘要：
介绍了LaO_（1-x）F_xFeAs化合物的Fe K-、As K-和La L_3边X射线吸收近边结构（XANES）测量结果。由于F取代O，Fe的K-边表现出向低能的化学位移、近边特征的改变和前边特征的抑制。前两个变化提供了电子电荷转移到Fe位的证据，后者直接支持将此电荷传递到Fe-3d轨道。As K-边缘测量示出了具有与p-区元素配位的过渡金属四面体的平面的化合物的典型光谱结构，如通过与其他这样的材料的比较所示。As-K边缘对掺杂的不敏感性以及强的Fe-K掺杂响应与能带结构计算一致，该计算显示这些材料中费米能附近基本上是纯Fe-d特征。以上的La-L3边缘的连续共振功能的能量被证明是定量与报道的La-O原子间的分离，并与其他含有稀土元素的氧化物化合物。
英文摘要：
Results of Fe K-, As K-, and La L3-edge x-ray absorption near edge structure (XANES) measurements on LaO1-xFxFeAs compounds are presented. The Fe K- edge exhibits a chemical shift to lower energy, near edge feature modifications, and pre-edge feature suppression as a result of F substitution for O. The former two changes provide evidence of electron charge transfer to the Fe sites and the latter directly supports the delivery of this charge into the Fe-3d orbitals. The As K- edge measurements show spectral structures typical of compounds with planes of transition-metal tetrahedrally coordinated to p-block elements as is illustrated by comparison to other such materials. The insensitivity of the As-K edge to doping, along with the strong Fe-K doping response, is consistent with band structure calculations showing essentially pure Fe-d character near the Fermi energy in these materials. The energy of the continuum resonance feature above the La-L3 edge is shown to be quantitatively consistent with the reported La-O inter-atomic separation and with other oxide compounds containing rare earth elements.
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