If the temperature
coefficient of the rate of
adsorption is very small, the adsorption process is said to be unactivated (i.e. to have a negligible
activation energy). In this case the
sticking coefficient at low coverages may be near unity particularly for smaller molecules.
Source:
PAC, 1976, 46, 71
(Manual of Symbols and Terminology for Physicochemical Quantities and Units - Appendix
II. Definitions, Terminology and Symbols in Colloid and Surface Chemistry. Part II:
Heterogeneous Catalysis)
on page 79