In order to study the adsorption mechanism of Hg on Au and Ag substrates, t
hin film Au(111) and Ag(111) substrates were exposed to gaseous metallic me
rcury, while the mercury concentration, substrate temperature, and exposure
length were varied. The resulting changes in the surface morphology of the
substrates were studied with scanning tunneling microscopy (STM). The amou
nt of adsorbed Hg required to cause saturation, i.e. a decrease in the adso
rption rate was found to be dependent on the mercury concentration and subs
trate temperature. The observations lead to the conclusion that the adsorpt
ion includes place exchange processes and concerted adsorption of more than
one Hg atom in one process. The results show that the collection efficienc
y of single-crystalline surfaces is a function of both mercury concentratio
n and temperature. Therefore, results from measurements performed at differ
ent conditions using single-crystalline surfaces may not be comparable.