https://doi.org/10.1007/s100510070113
Tracer diffusion and correlations in ordered adsorption systems with defect-controlled transport mechanisms
1
Institute of Physics of the National Academy of Sciences, pr.Nauki 46, 252028,
Kiev, Ukraine
2
Max-Planck-Institut für Eisenforschung, 40074 Düsseldorf, Germany
3
Lehrstuhl für Physikalische Chemie II, Universität Dortmund, 44227 Dortmund, Germany
Received:
20
September
1999
Revised:
14
April
2000
Published online: 15 October 2000
In this study we develop a theory of tracer diffusion in 2D lattice-gas systems with strongly repulsive nearest neighbor interactions. The study
is performed for a square lattice in the vicinity of half monolayer
coverage. In this case the lattice gas forms a highly-ordered c
phase. The adatom kinetics is reduced to the problem of random walks
of long-living structural defects. The correlated motion of
tracer-defect pairs is considered. Equations for correlation functions
of tracer-vacancy, tracer-excessive adatoms and tracer-dimer pairs are
derived and solved in terms of microscopic jump probabilities of
defects. The solutions are exact in the case of dominant single defect
transport mechanisms. In the case of dimer transport we applied the
approximation of short-range correlation length. The values obtained for
the correlation factor are in good agreement with the results of
computer simulations in the over-stoichiometric range, while for
sub-stoichiometric coverages the agreement is not very good.
PACS: 82.20.Mj – Nonequilibrium kinetics / 68.35.Fx – Diffusion; interface formation / 64.60.Cn – Order-disorder transformations; statistical mechanics of model systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000
