reaction probability, \(P_{\text{r}}\)

https://doi.org/10.1351/goldbook.R05176
The @[email protected] that a reaction occurs when two particles undergo a collision. If \(N_{\text{c}}\) is the number of collisions occurring in unit time, and \(N_{\text{r}}\) the number of reactions occurring in unit time: \(P_{\text{r}}=\frac{N_{\text{r}}}{N_{\text{c}}}\).
Source:
PAC, 1996, 68, 149. (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 184 [Terms] [Paper]