09213 IUPAC Gold Book - X-ray absorption near-edge spectroscopy 10.1351/goldbook.09213 09213 current acronym: XANES synonym: near-edge extended X-ray absorption fine structure spectroscopy (NEXAFS) 1 X-ray absorption fine structure spectroscopy in the energy region near (within approximately \(\pu{100 eV}\)) an absorption edge. XANES results from interference in multiple scattering of low-energy photoelectrons by surrounding atoms. It provides information on the local coordination environment, oxidation state, molecular orbitals, hybridization, and band structure (unoccupied electronic states). XANES measurements usually start some \(\pu{10 eV}\) before the core-level binding energy (the absorption edge) of the emitting atoms, because in many cases pre-edge features are used to identify chemical bonds, e.g. \(\uppi^{\ast}\) resonances (excitation into lowest unoccupied molecular orbitals) in C K-edge spectra of polymer samples. Usefully sharp absorption edges are commonly observed in X-ray absorption spectra, although broader increases can be observed for some inner-shell excitations with short lifetimes. X-ray absorption fine structure spectroscopy https://goldbook.iupac.org//terms/view/09212 PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1795 (https://doi.org/10.1515/pac-2019-0404) https://goldbook.iupac.org/terms/view/09213/html https://goldbook.iupac.org/terms/view/09213/json https://goldbook.iupac.org/terms/view/09213/plain Citation: 'X-ray absorption near-edge spectroscopy' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.09213 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-05-18T04:27:39+00:00