Functionalization of Si(553)-Au with hydrogen and small organic molecules

Atomic metallic chains on vicinal Si substrates can be used as templates for the growth of hybrid moleculesolid nanostructures. The advantage of these structures is the possibility to vary the substrate geometry and the metallic element, leading to a family of surfaces with a broad spectrum of potential applications in organic electronics and bio-sensing. We investigate the adsorption of toluene-3,4-dithiol molecules on hydrogenpassivated Si(553)-Au surfaces. Hydrogen is able to drive a reversible metal-insulator transition on the Si(553)- Au surface and also changes the adsorption geometry of organic molecules1 , extending the functionalization possibilities of the surface. We use surface-sensitive and polarization-sensitive optical techniques, such as Raman Spectroscopy (RS), Reflection Anisotropy Spectroscopy (RAS) and Infrared Spectroscopic Ellipsometry (IRSE) to establish a direct connection between optical spectra and surface structure via ab-initio calculations2 . Optical fingerprints allow us to gain information on structural and electronic properties of the system. The plan for the future is the realization of highly ordered molecular array geometries and the understanding of charge transfer between molecules and atomic wires. This will open possibilities for further functionalization through modification of terminal groups of molecules. Furthermore, the possibility to explore different chemical conditions between elementary organic molecules and surfaces at the nanoscale offer a new point of view for studies of complex biological molecules. References: [1] C. Hogan, E. Speiser, S. Chandola. S. Suchkova, J. Aulbach, J. Schäfer, S. Meyer, R. Claessen and N. Esser, publication in progress [2] C. Hogan, E. Ferraro, N. McAlinden and J.F. McGilp. PRL 111, 8, 087401 (2013)