03296 IUPAC Gold Book - isomer shift 10.1351/goldbook.I03296 I03296 current 1 Measure of the energy difference between the source (\(E_{\rm{s}}\)) and the absorber (\(E_{\rm{a}}\)) transition. The measured Doppler velocity shift, \(\delta \), is related to the energy difference by \[E_{\rm{a}}- E_{\rm{s}}=\frac{\delta \ E_{\gamma }}{c}\] where \(E_{\gamma }\) is the Mössbauer gamma energy and \(c\) is the speed of light in vacuum. absorber https://goldbook.iupac.org//terms/view/A00034 PAC, 1976, 45, 211. 'Nomenclature and Conventions for Reporting Mössbauer Spectroscopic Data' on page 214 (https://doi.org/10.1351/pac197645030211) https://goldbook.iupac.org/terms/view/I03296/html https://goldbook.iupac.org/terms/view/I03296/json https://goldbook.iupac.org/terms/view/I03296/plain Citation: 'isomer shift' 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.I03296 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. 2026-05-17T22:41:04+00:00