08420 IUPAC Gold Book - spin echo 10.1351/goldbook.08420 08420 current initialism: SE synonym: Hahn echo 1 Refocusing of spin magnetization usually by two consecutive radiofrequency pulses. The simplest form of the spin-echo pulse sequence consists of \(\pu{90\!^{\circ}}\ \rm{pulse}\), a \(\pu{180\!^{\circ}}\ \rm{pulse}\), and then an echo. The time between the middle of the first RF pulse and the peak of the spin echo is called the echo time (\(T_{\rm{E}}\)). SE is typically used within a pulse sequence to refocus chemical shift by pulses \(\pu{90\!^{\circ}}\), \(T_{\rm{E}}/2\), \(\pu{180\!^{\circ}}\), \(T_{\rm{E}}/2\). \(\pu{180\!^{\circ}}\ \rm{pulse}\) https://goldbook.iupac.org//terms/view/08310 \(\pu{90\!^{\circ}}\ \rm{pulse}\) https://goldbook.iupac.org//terms/view/08311 echo time https://goldbook.iupac.org//terms/view/08337 flip angle https://goldbook.iupac.org//terms/view/08343 pulse sequence https://goldbook.iupac.org//terms/view/08396 radiofrequency https://goldbook.iupac.org//terms/view/08279 PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 705 (https://doi.org/10.1515/pac-2019-0203) https://goldbook.iupac.org/terms/view/08420/html https://goldbook.iupac.org/terms/view/08420/json https://goldbook.iupac.org/terms/view/08420/plain Citation: 'spin echo' 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.08420 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. 2026-05-30T17:44:54+00:00