A combination of angle-resolved photoemission and scanning tunneling microscopy is used to explore the possibilities for tailoring the electronic structure of gold atom chains on silicon surfaces. It is shown that the interchain coupling and the band filling can be adjusted systematically by varying the step spacing via the tilt angle from Si͑111͒. Planes with odd Miller indices are stabilized by chains of gold atoms. Metallic bands and Fermi surfaces are observed. These findings suggest that atomic chains at stepped semiconductor substrates make a highly flexible class of solids approaching the one-dimensional limit.

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We report the synthesis of extended two-dimensional organic networks on Cu(111), Ag(111), Cu(110), and Ag(110) from thiophene-based molecules. A combination of scanning tunnelling microscopy and X-ray photoemission spectroscopy yields insight into the reaction pathways from single molecules towards the formation of two-dimensional organometallic and polymeric structures via Ullmann reaction dehalogenation and C-C coupling. The thermal stability of the molecular networks is probed by annealing at elevated temperatures of up to 500 °C. On Cu(111) only organometallic structures are formed, while on Ag(111) both organometallic and covalent polymeric networks were found to coexist. The ratio between organometallic and covalent bonds could be controlled by means of the annealing temperature. The thiophene moieties start degrading at 200 °C on the copper surface, whereas on silver the degradation process becomes significant only at 400 °C. Our work reveals how the interplay of a specific surface type and temperature steers the formation of organometallic and polymeric networks and describes how these factors influence the structural integrity of two-dimensional organic networks.