mean residence time

of adsorbed molecules
The mean time during which the molecules remain on the surface of the adsorbent, i.e. the mean time interval between impact and desorption.
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 (