long-lived collision complex

When a potential-energy surface is such that the system performs a number of vibrations and rotations in the region of a col, the corresponding intermediate is known as a long-lived collision complex, and the reaction is said to be indirect.
PAC, 1981, 53, 753. 'Symbolism and Terminology in Chemical Kinetics' on page 767 (https://doi.org/10.1351/pac198153030753)