AVS 54th International Symposium
    Surface Science Friday Sessions
       Session SS1-FrM

Invited Paper SS1-FrM5
Local Electronic Properties of Molecular Assemblies at Surfaces

Friday, October 19, 2007, 9:20 am, Room 608

Session: Surface Dynamics
Presenter: J.I. Pascual, Freie Universität Berlin, Germany
Correspondent: Click to Email

The electronic properties of inorganic functional materials can be understood and predicted from a conceptual knowledge of electron dynamics. However, when organic molecules are to be used in electronic devices an atomistic picture of molecular bonding is additionally required. Local phenomenology occurring at the nanoscopic scale related with molecular chemical bonding, and hence with electronic coupling, governs many of the mesoscopic properties of organic devices. On the one hand organic-inorganic bonding can be more relevant than the molecular functionality itself. On the other, intermolecular interactions play a key role in structural organization of the molecular layer, and eventually govern the three-dimensional growth of molecular thin-films, beyond the interface limit. Our research in Berlin aims to provide a molecular scale picture about interactions occurring at the inorganic/organic interface. Our approach to this goal follows a combination of low-temperature scanning tunnelling microscopy and spectroscopy measurements with density functional theory simulations. We characterise the electronic structure of single molecules on a surface with sub-nanometer resolution in order to resolve the influence of local parameters (molecular orientation, neighbourhood, conformation,…) on its properties. Non covalent intermolecular interactions are also relevant at the inorganic interface, and may lead to the construction of three-dimensional supramolecular nanostructures with interesting electronic properties. In this seminar I will present several of our recent results about the electronic configuration of model molecular systems like C60, fullerene-based nanostructures and charge-transfer complexes on metal and semiconductors surfaces. The electronic configuration of the molecular ensembles will be analyzed in terms of their local neighbourhood and the degree of electronic coupling with the metal suface.