Formation, atomic distribution and mixing energy in two-dimensional PdxAg1x surface alloys on Pd(111)

The formation and atom distribution in two-dimensional Pd x Ag 1 x /Pd(111) monolayer surface alloys were studied by high resolution scanning tunnelling microscopy (STM) with chemical contrast. From short-range order (SRO) parameters, we calculate preferences for like or unlike nearest neighbours to...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Hauptverfasser: Engstfeld, A. K, Hoster, H. E, Behm, R. J
Format: Artikel
Sprache:eng
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:The formation and atom distribution in two-dimensional Pd x Ag 1 x /Pd(111) monolayer surface alloys were studied by high resolution scanning tunnelling microscopy (STM) with chemical contrast. From short-range order (SRO) parameters, we calculate preferences for like or unlike nearest neighbours to elucidate the mixing behaviour of the two components for various sub monolayer Ag surface contents. In the regime of low Ag surface contents (60% Ag) result in a disperse distribution of the atoms in the surface. Effective pair interactions (EPIs) were derived by comparing the measured distribution with distributions obtained using Monte Carlo (MC) simulations. From the EPIs, we derived a function for the mixing energy, which can describe the change from clustering to a disperse distribution. The effects of the resulting surface atom distributions and of the Ag coverage dependent surface mixing/demixing on catalytic reactions are discussed. Determination of surface alloy mixing energies from atomically resolved STM images.
ISSN:1463-9076
1463-9084
DOI:10.1039/c2cp41104k