Term: channel https://doi.org/10.1351/goldbook.C00970 Definition: Regions of potential-energy surfaces where there are valleys are sometimes referred to as arrangement channels. The reactant channel or entrance channel is that corresponding to configurations similar to those of the reactants; the product channel or exit channel relates to configurations similar to those of the products. In collision theory, the specification of a complete set of quantum numbers in a given arrangement channel is called a channel. Related Terms: 1) entrance channel (http://doi.org/10.1351/goldbook.E02148). 2) exit channel (http://doi.org/10.1351/goldbook.E02265). 3) potential-energy surfaces (http://doi.org/10.1351/goldbook.P04780). 4) reactant (http://doi.org/10.1351/goldbook.R05163). 5) product (http://doi.org/10.1351/goldbook.P04861). 6) collision theory (http://doi.org/10.1351/goldbook.C01170). Source: PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 157 (https://doi.org/10.1351/pac199668010149) Citation: 'channel' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.C00970 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. 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.