Department of Physics, Yeshiva University, New York, New York 10016, USA.
Annu Rev Anal Chem (Palo Alto Calif). 2011;4:23-39. doi: 10.1146/annurev-anchem-061010-113906.
Many metal clusters in the 1-nm size range are catalytically active, and their enhanced reactivity is often attributed to their size, structure, morphology, and details of alloying. Synchrotron sources provide a wide range of opportunities for studying catalysis. Among them, extended X-ray absorption fine-structure (EXAFS) spectroscopy is the premier method for investigating structure and composition of nanocatalysts. In this review, we summarize common methods of EXAFS analysis for geometric and compositional characterization of nanoparticles. We discuss several aspects of the experiments and analyses that are critical for reliably modeling EXAFS data. The most important are sample homogeneity, the width of the size and compositional distribution functions, and accounting for multiple-scattering contributions to EXAFS. We focus on the contribution of structural disorder and structural/compositional heterogeneity to the accuracy of three-dimensional modeling.
许多 1nm 大小范围内的金属簇具有催化活性，其增强的反应性通常归因于它们的尺寸、结构、形态和合金化细节。同步辐射源为研究催化提供了广泛的机会。其中，扩展 X 射线吸收精细结构（EXAFS）光谱是研究纳米催化剂结构和组成的首选方法。在这篇综述中，我们总结了用于纳米粒子的几何和组成特征描述的 EXAFS 分析的常用方法。我们讨论了对可靠地对 EXAFS 数据进行建模至关重要的实验和分析的几个方面。最重要的是样品的均一性、尺寸和组成分布函数的宽度以及对 EXAFS 的多次散射贡献的考虑。我们专注于结构无序和结构/组成非均匀性对三维建模准确性的贡献。
