XAFS基础知识

1区 地球科学 Q1 Earth and Planetary Sciences
M. Newville
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引用次数: 292

摘要

介绍了x射线吸收精细结构(XAFS)的基本物理原理。XAFS是一种元素特异性光谱学,通过调整特定元素的选定核心能级结合能及以上的x射线能量来进行测量。虽然XAFS是一种成熟的技术,可以提供有关探测原子的化学和物理环境的可靠和有用的信息,但它对能量可调x射线源的要求意味着它主要是用同步辐射源完成的,因此与其他光谱分析方法相比,它不太常见。XAFS光谱对所选元素的氧化态和配位化学反应特别敏感。此外,XAFS光谱的扩展振荡对所选元素周围原子的距离、配位数和种类都很敏感。扩展x射线吸收精细结构(EXAFS)是本章的主要重点。由于它是特定于元素的,XAFS对样品的形式几乎没有限制,并且可以在各种系统和散装物理环境中使用,包括晶体,玻璃,液体和异质混合物。此外,XAFS通常可以在低浓度元素(通常低至几ppm)上进行,因此在广泛的科学领域中有应用,包括化学、生物学、催化研究、材料科学、环境科学和地质学。本章特别关注EXAFS光谱分析和建模中使用的基本概念。x射线吸收精细结构(XAFS)是原子在接近或高于原子核能级电子结合能的能量处对x射线吸收概率的调制。XAFS是由吸收原子的化学和物理状态引起的。XAFS光谱对形式氧化态、配位化学以及所选材料周围原子的距离、配位数和种类特别敏感。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Fundamentals of XAFS
The basic physical principles of X-ray Absorption Fine-Structure (XAFS) are presented. XAFS is an element-specific spectroscopy in which measurements are made by tuning the X-ray energy at and above a selected core-level binding energy of a specified element. Although XAFS is a well-established technique providing reliable and useful information about the chemical and physical environment of the probe atom, its requirement of an energy-tunable X-ray source means it is primarily done with synchrotron radiation sources and so is somewhat less common than other spectroscopic analytical methods. XAFS spectra are especially sensitive to the oxidation state and coordination chemistry of the selected element. In addition, the extended oscillations of the XAFS spectra are sensitive to the distances, coordination number and species of the atoms immediately surrounding the selected element. This Extended X-ray Absorption Fine-Structure (EXAFS) is the main focus of this chapter. As it is element-specific, XAFS places few restrictions on the form of the sample, and can be used in a variety of systems and bulk physical environments, including crystals, glasses, liquids, and heterogeneous mixtures. Additionally, XAFS can often be done on low-concentration elements (typically down to a few ppm), and so has applications in a wide range of scientific fields, including chemistry, biology, catalysis research, material science, environmental science, and geology. Special attention in this chapter is given to the basic concepts used in analysis and modeling of EXAFS spectra. X-ray absorption fine structure (XAFS) is the modulation of an atom’s X-ray absorption probability at energies near and above the binding energy of a core-level electron of the atom. The XAFS is due to the chemical and physical state of the absorbing atom. XAFS spectra are especially sensitive to the formal oxidation state, coordination chemistry, and the distances, coordination number and species of the atoms immediately surrounding the selected …
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来源期刊
Reviews in Mineralogy & Geochemistry
Reviews in Mineralogy & Geochemistry 地学-地球化学与地球物理
CiteScore
8.30
自引率
0.00%
发文量
39
期刊介绍: RiMG is a series of multi-authored, soft-bound volumes containing concise reviews of the literature and advances in theoretical and/or applied mineralogy, crystallography, petrology, and geochemistry. The content of each volume consists of fully developed text which can be used for self-study, research, or as a text-book for graduate-level courses. RiMG volumes are typically produced in conjunction with a short course but can also be published without a short course. The series is jointly published by the Mineralogical Society of America (MSA) and the Geochemical Society.
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