Although X-ray absorption spectroscopy (XAS) was conceived in the early 20th century, it took 60 years after the advent of synchrotrons for researchers to exploit its tremendous potential. Counterintuitively, researchers are now developing bench type polychromatic X-ray sources that are less brilliant to measure catalyst stability and work with toxic substances. XAS measures the absorption spectra of electrons that X-rays eject from the tightly bound core electrons to the continuum. The spectrum from 10 to 150 eV (kinetic energy of the photoelectrons) above the chemical potential—binding energy of core electrons—identifies oxidation state and band occupancy (X-ray absorption near edge structure, XANES), while higher energies in the spectrum relate to local atomic structure like coordination number and distance, Debye-Waller factor, and inner potential correction (extended X-ray absorption fine structure, EXAFS). Combining XAS with complementary spectroscopic techniques like Raman, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) elucidates the nature of the chemical bonds at the catalyst surface to better understand reaction mechanisms and intermediates. Because synchrotrons continue to be the light source of choice for most researchers, the number of articles Web of Science indexes per year has grown from 1000 in 1991 to 1700 in 2020. Material scientists and physical chemists publish an order of magnitude articles more than chemical engineers. Based on a bibliometric analysis, the research comprises five clusters centred around: electronic and optical properties, oxidation and hydrogenation catalysis, complementary analytical techniques like FTIR, nanoparticles and electrocatalysis, and iron, metals, and complexes.

中文翻译：

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化学工程中的实验方法：X射线吸收光谱——XAS、XANES、EXAFS

尽管 X 射线吸收光谱 (XAS) 是在 20 世纪初构思的，但在同步加速器问世后 60 年，研究人员才发现其巨大潜力。与直觉相反，研究人员现在正在开发台式多色 X 射线源，这些源在测量催化剂稳定性和处理有毒物质方面的效果较差。XAS 测量 X 射线从紧密结合的核心电子发射到连续体的电子的吸收光谱。化学势（核心电子的结合能）上方 10 到 150 eV（光电子的动能）的光谱确定氧化态和能带占有率（X 射线吸收近边缘结构，XANES），而光谱中较高的能量与局部原子结构，如配位数和距离，德拜-沃勒因子，和内电位校正（扩展的 X 射线吸收精细结构，EXAFS）。将 XAS 与拉曼、傅里叶变换红外 (FTIR)、X 射线光电子能谱 (XPS) 和电子顺磁共振 (EPR) 等互补光谱技术相结合，阐明了催化剂表面化学键的性质，以更好地了解反应机制和中间体. 由于同步加速器仍然是大多数研究人员的首选光源，因此 Web of Science 索引每年的文章数量从 1991 年的 1000 篇增加到 2020 年的 1700 篇。材料科学家和物理化学家发表的文章数量比化学工程师多一个数量级. 基于文献计量分析，该研究包括五个集中在：电子和光学性质、氧化和氢化催化、