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.
See also: entrance channel, exit channel
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)
That part of an analytical instrument that is dedicated to a single analytical procedure, including the transducer. This term relates to the internal operation of certain types of instruments, particularly in clinical chemistry. The general term channel has a much broader meaning, and the term is not recommended.
Source: PAC, 1989, 61, 1657. 'Nomenclature for automated and mechanised analysis (Recommendations 1989)' on page 1661 (https://doi.org/10.1351/pac198961091657)