Combined structure analysis of STM and surface XAFS for self-assembly of metal-thiolate complex at equilibrium: Hexanethiolate on Cu(1Â 1Â 1)

The structure of 1-hexanethiolate (C6H13S) self-assembled monolayers adsorbed onto a Cu(1 1 1) surface was studied with a combination of scanning tunneling microscopy (STM), and carbon and sulfur K-edge X-ray absorption fine structure (XAFS) experiments. S K-XAFS confirmed that sulfur adsorbs onto deep three-fold hollow sites. Moreover, these sites appear to shrink with a small anisotropy between adsorption and equilibrium. STM further revealed three different ordered superstructures. Finally, a single long-range ordered phase exhibiting a striped moiré pattern is imaged at thermodynamic equilibrium.