unactivated adsorption process 

https://doi.org/10.1351/goldbook.U06552
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 [Terms] [Paper]
Citation: 'unactivated adsorption process' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.U06552 RIS BibTex EndNote
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Last revised: February 24, 2014