THEORY OF EXTENDED X-RAY ABSORPTION-EDGE FINE-STRUCTURE (EXAFS) IN CRYSTALLINE SOLIDS
THEORY OF EXTENDED X-RAY ABSORPTION-EDGE FINE-STRUCTURE (EXAFS) IN CRYSTALLINE SOLIDS
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DOI：
10.1103/physrevb.11.1279
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发表时间：
1975-01-01
影响因子：
3.7
通讯作者：
DONIACH, S
中科院分区：
文献类型：
--
作者：
ASHLEY, CA;DONIACH, S
在单电子近似的框架内给出了扩展X射线吸收边精细结构的一般理论。提出了对该理论的近似评估，允许从理论计算的电子原子散射相移开始简单地计算光谱。这与在 K 边缘以上 200-800 eV 能量范围内观察到的铜光谱非常吻合，无需使用任何可调参数。对一般理论中的多重散射效应进行了定性评估，在 100 eV 以下应该相当不错。人们发现多重散射校正对于密堆积结构的光谱低能区域非常重要。结果表明，单次散射振幅可能会发生显着抵消，这可以解释斯特恩、塞耶斯和莱特尔发现的铜光谱中的详细异常现象。
A general theory of the extended x-ray absorption edge fine structure is given within the framework of a one-electron approximation. An approximate evaluation of this theory is proposed which allows a simple calculation of the spectrum starting from theoretically calculated electron-atom scattering phase shifts. This is shown to agree quite well with the observed spectrum for copper in the energy range 200-800 eV above the K edge without the use of any adjustable parameters. A qualitative evaluation of multiple scattering effects in the general theory is made which should be reasonably good below 100 eV. Multiple scattering corrections are found to be very important in the low-energy region of the spectrum for close-packed structures. It is shown that significant cancellation of single scattering amplitudes can occur which could account for detailed anomalies in the spectrum of Cu found by Stern, Sayers, and Lytle.