MESOSCOPIC STRUCTURAL TRANSFORMATIONS OF THE AU(111) SURFACE-INDUCED BY ALKALI-METAL ADSORPTION

The response of the Au(111) surface reconstruction on the adsorption of Na and K atoms was studied by means of scanning tunneling microscopy. With increasing coverage the periodicity of the chevron structure decreases continuously from about 250 to 100 angstrom. For Na coverages exceeding theta almost-equal-to 0.20 the stacking fault lines become distorted and eventually a poorly ordered domain structure with hexagonal symmetry and even higher density of Au atoms is formed at theta almost-equal-to 0.23. These effects are attributed to an adsorbate-induced weakening of the coupling between the first two Au layers by which the influence of the elastic stress within the topmost layer becomes more dominant.