Term: collision efficiency, Bc
https://doi.org/10.1351/goldbook.C01164

Definition:
The collision efficiency, or de-energization efficiency, is defined by: \[k_{\text{-1}} = B_{\text{c}}\ k_{\text{-1}}^{\text{sc}}\] where k-1 is the rate constant for a particular substance M when it brings about the de-energization process C01164.png and k-1sc is the corresponding rate constant for a reference molecule M r that de-energizes A* on every collision; that is, the reference molecule M r undergoes strong collisions, and by definition has a collision efficiency Bc of unity. The species A* is usually in a vibrationally-excited state, and A has energy less than that required for reaction to occur.

Related Terms:
1) rate constant (http://doi.org/10.1351/goldbook.O04322).
2) strong collisions (http://doi.org/10.1351/goldbook.S06059).
3) excited state (http://doi.org/10.1351/goldbook.E02257).

Image: Not defined (https://goldbook.iupac.org/img/inline/C01164.png) 

Source: PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 159 (https://doi.org/10.1351/pac199668010149)

Citation: 'collision efficiency, Bc' 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.C01164

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