Structural components of thePt/Si(111)−(3×3)surface from scanning tunneling microscopy

Abstract

From topographic inspection of the $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})\text{-Pt}/\text{Si}(111)$ surface by scanning tunneling microscopy, key structural elements are identified. A characteristic triangular building block in each $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})$ unit cell, composed of charge maxima at approximately the bulk Pt-Pt distance bond, is observed. The orientation of the trimers is incompatible with the Si(111) substrate symmetry, which becomes obvious at domain-wall boundaries. In consequence, a simple top-layer trimer model is rendered insufficient. Instead, the finding of rotated trimers points at a more complex rearrangement of the surface, which generates the observed symmetry-breaking structural relaxation that leads to a chiral surface.