Optical characterization of the Si (553)-Au surface functionalized with hydrogen and small organic molecules

Atomic metallic chains on vicinal Si substrates can be used as templates for the growth of hybrid molecule-solid 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 hydrogen-passivated Si(553)-Au surfaces. Hydrogen is able to drive a reversible metal-insulator transition on the Si(553)-Au surface and also changes the desorption geometry of organic molecules, extending the functionalization possibilities of the surface. We use surface-sensitive and polarization-sensitive optical techniques, such as Reflection Anisotropy Spectroscopy (RAS) and Raman Spectroscopy (RS) to establish a direct connection between optical spectra and surface structure via ab-initio calculations. 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. (author)