weak collision

A collision between two molecules in which the amount of energy transferred from one to the other is not large compared to $k B T$ ( $k B$ is the Boltzmann constant and $T$ the absolute temperature).

See: strong collision

Source:

PAC, 1996, 68, 149 (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 191