A situation in which molecules of @A00152@ are free to move about the surface. @M03955-1@ of the @A00152@ will increase with temperature and mobile adsorption may be either localized or non-localized. In localized mobile adsorption the @A00152@ spends most of the time on the adsorption sites but can migrate or be desorbed and readsorbed elsewhere. In non-localized adsorption the @M03955-2@ is so great that a small fraction of the adsorbed species is on the @D01620@ sites and a large fraction at other positions on the surface.