Paper SS1-WeM5
W-oxide Clusters on Cu(110) Surfaces: Electronic Structure and Selforganisation

Wednesday, October 20, 2010, 9:20 am, Room Picuris

Oxide clusters with well-defined size and stoichiometry supported on metal surfaces are interesting nanoscale objects with attractive features for both fundamental research and technological applications. It has been shown recently that (WO₃)₃ cluster molecules, formed by vacuum sublimation of WO₃ powder, can be deposited as monodispersive clusters on TiO₂ (110) surfaces [1]. In the present work, we investigate the interaction and electronic properties of (WO₃)₃ species at the single molecule level with Cu(110) and reconstructed Cu(110)-O surfaces using low-temperature (5K) scanning tunneling microscopy (STM) and spectroscopy (STS). In order to decouple the (WO₃)₃ cluster states from the metal substrate states, the clusters have been deposited also on a NaCl buffer layer (grown on Cu(110)). The comparison of the STM (STS) fingerprints of the (WO₃)₃ clusters on the NaCl and the Cu surfaces, together with respective DFT calculations, allows us to gauge the cluster-Cu interaction and to determine the hybridisation of the cluster orbitals with metal states. At low temperature (<20K) the (WO₃)₃ clusters are stable as individual units on the Cu(-O) surfaces, but at elevated temperature (room temperature and above) the clusters react with Cu substrate atoms. They selforganise via condensation and, depending on the coverage, form 1-D W-oxide line structures (nanowires) or arrange into ordered 2-D W-oxide nanolayer phases with well-defined atomic structures. These 2-D structures are investigated experimentally with STM and LEED and theoretically by DFT calculations.

Supported by the ERC Advanced Grant SEPON

[1] O. Bondarchuk, X. Huang, J. Kim, B.D. Kay, L.-S. Wang, J.M. White, Z. Dohnalek, Angew. Chem. Int. Ed. 45 (2006) 4786