{"term":{"id":"00366","title":"annihilation","longtitle":"IUPAC Gold Book - annihilation","doi":"10.1351\/goldbook.A00366","code":"A00366","status":"current","also defines":"<em>also defines<\/em>: singlet-singlet annihilation","synonym":"<em>synonym<\/em>: energy pooling","definitions":[{"id":1,"text":"An interaction between a particle and its antiparticle in which they both disappear.","contexts":[],"links":[{"term":"antiparticle","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/A00401"}],"sources":["Orange Book, 2nd ed., p. 211 (https:\/\/media.iupac.org\/publications\/analytical_compendium\/)"]},{"id":2,"text":"Two atoms or molecular entities both in an excited electronic state interact often (usually upon collision) to produce one atom or molecular entity in an excited electronic state and another in its ground electronic state. This phenomenon (annihilation) is sometimes referred to as 'energy pooling'.","contexts":[],"links":[{"term":"electronic state","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/ET07026"},{"term":"spin conservation rule","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S05862"},{"term":"triplet-triplet annihilation","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/T06505"}],"sources":["PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2228 (https:\/\/doi.org\/10.1351\/pac199668122223)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/A00366\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/A00366\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/A00366\/plain"},"citation":"Citation: 'annihilation' 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.A00366","license":"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.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"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.","accessed":"2026-07-31T15:30:48+00:00"}}