Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Rev Sci Instrum. 2023 Feb 1;94(2):023102. doi: 10.1063/5.0133896.
High-energy resolution core-level spectroscopies, including a group of different techniques to obtain element-specific information of the electronic structure around an absorption site, have become powerful tools for studying the chemical state, local geometric structure, and the nature of chemical bonding. High-resolution x-ray absorption and x-ray emission spectroscopies are well-established experimental techniques but have always been limited by the number of emitted photons and the limited acceptance of solid angles, as well as requiring high energy stability and repeatability for the whole experimental setup. A full-cylindrical x-ray spectrometer based on flexible HAPG (highly annealed pyrolitic graphite) mosaic crystals is an effective solution for the above issues. However, large-area HAPG remains expensive and is often not easy to access. Here, we present an alternative approach by using segmented single crystals (Si and Ge) with different orientations instead of the HAPG as a dispersive element. The proposed method drastically improved the energy resolution up to 0.2-2 eV in the range of 2-10 keV. High-pressure x-ray emission and resonant x-ray emission spectra are presented to demonstrate the capabilities of the instrument. The new design is particularly suitable for high-resolution spectroscopy applications at fourth-generation synchrotron radiation sources or free-electron lasers.
高能量分辨率的芯能级谱学，包括一组不同的技术，用于获取吸收位置周围电子结构的元素特异性信息，已成为研究化学状态、局部几何结构和化学键性质的有力工具。高分辨率 X 射线吸收和 X 射线发射光谱学是成熟的实验技术，但一直受到发射光子数量和固体角的限制，以及整个实验装置对能量稳定性和重复性的要求的限制。基于柔性高取向热解石墨（HAPG）镶嵌晶体的全圆柱 X 射线光谱仪是解决上述问题的有效方法。然而，大面积 HAPG 仍然昂贵，而且通常不容易获得。在这里，我们提出了一种替代方法，使用不同取向的分段单晶（Si 和 Ge）代替 HAPG 作为色散元件。所提出的方法在 2-10 keV 的范围内将能量分辨率显著提高到 0.2-2 eV。展示了高压 X 射线发射和共振 X 射线发射光谱来证明该仪器的性能。该新设计特别适用于第四代同步辐射光源或自由电子激光的高分辨率光谱学应用。
