{"term":{"id":"01773","title":"direct reaction","longtitle":"IUPAC Gold Book - direct reaction","doi":"10.1351\/goldbook.D01773","code":"D01773","status":"current","also defines":"<em>also defines<\/em>: impulsive reaction","definitions":[{"id":1,"text":"A chemical process in which the reactive complex has a lifetime that is shorter than its period of rotation. In a molecular-beam experiment the reaction products of a direct reaction are scattered, with reference to the centre of mass of the system, in preferred directions rather than at random. Some direct reactions are impulsive which means that there is an energy exchange that is very fast compared to the vibrational time scale. A direct reaction is to be contrasted with an indirect reaction, also known as a complex-mode reaction.","links":[{"term":"complex-mode reaction","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/C01206"},{"term":"indirect reaction","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/I03011"},{"term":"lifetime","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/L03515"},{"term":"molecular-beam","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/M03982"},{"term":"reactive complex","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/R05182"}],"sources":["PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 163 (https:\/\/doi.org\/10.1351\/pac199668010149)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/D01773\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/D01773\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/D01773\/plain"},"citation":"Citation: 'direct reaction' 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.D01773","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":"2026-04-20T14:10:47+00:00"}}