Spherically bent mica analyzers as universal dispersing elements for X‐ray spectroscopy
Spherically bent mica analyzers as universal dispersing elements for X‐ray spectroscopy
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DOI：
10.1002/xrs.3143
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发表时间：
2020-03
影响因子：
1.2
通讯作者：
E. S. Joseph;Evan P. Jahrman;G. Seidler
中科院分区：
文献类型：
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作者：
E. S. Joseph;Evan P. Jahrman;G. Seidler
球形弯曲晶体分析仪（SBCA）在非常高分辨率的硬X射线波长色散X射线荧光光谱（通常称为X射线发射光谱（XES））中有相当多的用途。虽然Si和Ge是SBCA最常用的衍射成分，但我们在这里考虑白云母作为分散元素的经典选择。我们发现，最高质量的云母基SBCA的各种谐波在硬X射线范围内显示出典型Si或Ge SBCA每单位立体角积分反射率的~5-~40%，并且云母SBCA具有与传统SBCA相当的能量分辨率。有趣的是，云母的选择带来了实际的好处：初级（0，0，2）反射具有足够强的谐波，这些谐波在能量上间隔相当紧密，因此当在罗兰圆光谱仪中以方便的布拉格角使用时，它们跨越了从~4到~11 keV的整个能量范围。因此，通过选择正确的云母（0，0，2）谐波和最终的能量色散固态检测器，单个云母SBCA可以用于三维过渡金属的每个K壳层发射线和镧系元素的每个L壳层发射线。效率的损失被操作效率抵消，即，单个分析仪在非常大的元素范围内的“通用”应用。这种性能表明云母SBCA在硬X射线范围内的实验室XES和同步加速器光子输入、光子输出光谱学中的未来应用。
Spherically‐bent crystal analyzers (SBCAs) see considerable use in very high‐resolution hard X‐ray wavelength dispersive X‐ray fluorescence spectroscopy, often called X‐ray emission spectroscopy (XES). While Si and Ge are the most frequently used diffractive components of SBCAs, we consider here the somewhat classical choice of muscovite mica as the dispersing element. We find that the various harmonics of a highest‐quality mica‐based SBCA show ~5–~40% of the integral reflectivity per unit solid angle of a typical Si or Ge SBCA in the hard X‐ray range, and that the mica SBCA have comparable energy resolution to the traditional SBCAs. Interestingly, the choice of mica comes with a practical benefit: the primary (0,0,2) reflection has sufficiently strong harmonics that are fairly tightly spaced in energy so that they span the complete energy range from ~4 to ~11 keV when used at convenient Bragg angles in a Rowland circle spectrometer. Hence, a single mica SBCA can be used for every K‐shell emission line of three dimensional transition metals and every L‐shell emission line of the lanthanide elements simply by selecting the correct mica (0,0,2) harmonic with a final energy‐dispersive solid state detector. The loss in efficiency is counteracted by an operational efficiency, i.e., the “universal” application of a single analyzer over a very large range of elements. This performance suggests future application of mica SBCAs in both laboratory‐based XES and synchrotron‐based photon‐in, photon‐out spectroscopies in the hard X‐ray range.