X-ray standing-wave investigations of valence electronic structure
X-ray standing-wave investigations of valence electronic structure
复制标题
价电子结构的 X 射线驻波研究
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
J. Woicik
中科院分区：
文献类型：
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作者：
J. Woicik
我们研究了Cu，Ge，GaAs，InP和NiO单晶在强X射线布拉格反射条件下的价电子发射，存在由入射和反射的X射线束的叠加产生的空间调制的X射线驻波干涉场。这些晶体跨越固态键合的整个金属、共价和离子范围。它表明，价电子发射是紧密耦合的原子核，即使是接近金属费米边缘的电子状态。使用键轨道近似，x射线驻波结构因子的价电子发射的推导出的键极性和光电离截面的晶体晶胞内的原子和实验相比。此外，我们还证明，通过利用布拉格条件下电场强度的空间依赖性，可以获得特定位置的价电子结构。该技术被证明为GaAs和NiO。
We have examined the valence-electron emission from Cu, Ge, GaAs, InP, and NiO single crystals under the condition of strong x-ray Bragg reflection; i.e., in the presence of the spatially modulated x-ray standing-wave interference field that is produced by the superposition of the incident and reflected x-ray beams. These crystals span the entire metallic, covalent, and ionic range of solid-state bonding. It is demonstrated that the valence-electron emission is closely coupled to the atomic cores, even for electron states close to a metallic Fermi edge. Using the bond-orbital approximation, the x-ray standing-wave structure factor for valence-electron emission is derived in terms of the bond polarities and photoionization cross sections of the atoms within the crystalline unit cell and compared to experiment. Additionally, we demonstrated that by exploiting the spatial dependence of the electric-field intensity under Bragg condition, site specific valence electronic structure may be obtained. The technique is demonstrated for GaAs and NiO.