The valence-to-core (V2C) portion of x-ray emission spectroscopy (XES) measures the electron states close to the Fermi level. These states are involved in bonding, thus providing a measure of the chemistry of the material. In this article, we show the V2C XES spectra for several niobium compounds. The $K{\beta }^{″}$ peak in the V2C XES results from the transition of a ligand $2s$ electron into the $1s$ core-hole of the niobium, a transition allowed by hybridization with the niobium $4p$. This location in energy of this weak peak shows a strong ligand dependence, thus providing a sensitive probe of the ligand environment about the niobium.

中文翻译：

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铌的非共振价核 X 射线发射光谱

X 射线发射光谱 (XES) 的价核 (V2C) 部分测量接近费米能级的电子态。这些状态参与键合，从而提供了材料化学性质的测量。在本文中，我们展示了几种铌化合物的 V2C XES 光谱。这$K{\beta }^{”}$V2C XES 中的峰源自配体的转变$2s$电子进入$1s$铌的核孔，通过与铌杂化而允许的转变$4p$。该弱峰的能量位置显示出强烈的配体依赖性，从而提供了铌周围配体环境的灵敏探针。