X-ray absorption fine structure (XAFS) spectroscopy is in use as a unique fingerprinting technique. By employing spectra of well-defined chemical species (standards), XAFS can be analyzed for speciation, i.e., identification and quantification of the different chemical species present in a sample. Several approaches to analyze the XAFS data for speciation have been developed. The principal component analysis and target transformation method are the two methods generally applied to check the number and identity of components in a sample. A widely used method for quantitatively determining the percentage of the species in the sample is linear combination fitting method, which can be applied to XANES spectra, derivative XANES spectra and EXAFS spectra. Other methods include residual phase analysis, normalized difference absorption edge analysis, pre-edge analysis method, derivative spectra methods and a method based on the relative position of the edge. The aim of the present article is to review the different (nearly all) methods of speciation using XAFS. The theory and principle of the different methods have been described and the analysis procedures for the methods have been illustrated with the help of examples. Some selected studies involving different elements have been reviewed and discussed.

中文翻译：

---

使用X射线吸收精细结构（XAFS）的物种形成

X射线吸收精细结构（XAFS）光谱被用作一种独特的指纹技术。通过使用定义明确的化学物种（标准品）的光谱，可以分析XAFS的形态，即鉴定和量化样品中存在的不同化学物种。已经开发了几种分析XAFS数据用于物种形成的方法。主成分分析和目标转换方法是通常用于检查样品中成分的数量和身份的两种方法。用于定量确定样品中物种百分比的一种广泛使用的方法是线性组合拟合方法，该方法可以应用于XANES光谱，XANES衍生光谱和EXAFS光谱。其他方法包括残留相位分析，归一化差吸收边缘分析，预边缘分析方法，导数光谱方法和基于边缘相对位置的方法。本文的目的是回顾使用XAFS的不同（几乎所有）物种形成方法。描述了不同方法的理论和原理，并借助实例说明了这些方法的分析过程。一些涉及不同要素的选定研究已被审查和讨论。