collision efficiency, Bc

Synonym: de-energization efficiency
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
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.
PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 159 (