ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
The kinetics of krypton adsorption on Pt(111) were investigated using supersonic molecular beam techniques. Krypton adsorbs at defects via an intrinsic precursor below a surface temperature of 85 K. The difference in activation energies for desorption and migration of a Kr atom on the terrace seeking a defect site is 10.7 kJ/mol, indicating that at 80 K, a Kr atom makes about 107 site hops before desorbing or finding a binding site. Below 60 K stable adsorption occurs on terraces, where the initial adsorption probability is independent of surface temperature. The activation energy for zero-order desorption from Pt(111) terraces is 12.9 kJ/mol; the activation energy for Kr migration on the terraces is then calculated to be ≤2.2 kJ/mol. Krypton adsorption proceeds at nonzero coverages via an extrinsic precursor. The adsorption probability of Kr increases with self-coverage, and is described by the modified Kisliuk model [H. C. Kang, C. B. Mullins, and W. H. Weinberg, J. Chem. Phys. 92, 1397 (1990); C. R. Arumainayagam, M. C. McMaster, and R. J. Madix, J. Phys. Chem. 95, 2461 (1991)]. The Kr overlayer on terraces compresses between 60 and 42 K, then forms a second state before forming stable multilayers at 34 K. © 2001 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.1350816
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