W. Arabczyk et U. Narkiewicz, THE EFFECT OF THE REAL CRYSTAL-STRUCTURE OF IRON ON THE BEHAVIOR OF SURFACE CONTAMINANTS, Surface science, 404(1-3), 1998, pp. 502-507
The segregation kinetics studies of sulphur and carbon in iron and the
adsorption kinetics of oxygen on iron have been discussed, taking int
o account the real structure of the monocrystalline sample. The deviat
ion of the kinetics results from the t(1/2) law has been interpreted a
s the effect of the presence of the adsorption sites in the defects of
the monocrystalline iron sample. The equilibrium between the adsorpti
on states of sulphur, carbon and oxygen atoms in the defects and on th
e surface has been assumed. For sulphur and carbon atoms, the energeti
cally more favourable adsorption sites are in the defects; however, fo
r oxygen atoms the adsorption sites on the surface are more favourable
. The free energy of the segregation of sulphur and carbon atoms from
the defects to the surface has been assumed to be a linear function of
the degree of filling of the adsorption sites in the defects. The cal
culations of the energies of iron clusters with a contaminant atom hav
e been also considered. (C) 1998 Elsevier Science B.V. All rights rese
rved.