AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThM

Paper SS1-ThM1
Interaction of Gold Atoms and Clusters with Color Centers on the Surface of MgO(001) Thin Films

Thursday, November 16, 2006, 8:00 am, Room 2002

Session: Reactivity of Oxide Surfaces I
Presenter: M. Sterrer, Fritz-Haber-Institute of the Max-Planck-Society, Germany
Authors: M. Sterrer, Fritz-Haber-Institute of the Max-Planck-Society, Germany
T. Risse, Fritz-Haber-Institute of the Max-Planck-Society, Germany
G. Pacchioni, University of Milano-Bicocca, Italy
H.-J. Freund, Fritz-Haber-Institute of the Max-Planck-Society, Germany
Correspondent: Click to Email
Catalytic activity of metal clusters may strongly be influenced by the properties of the underlying oxide support. The Au/MgO system has emerged to a prototype example in this respect because of the possibility for charge transfer from surface trapped electron centers (color centers) to adsorbed metal atoms and clusters, thus forming negatively charged metal particles. In this contribution, experimental results on the properties of single gold atoms nucleated on regular as well as color center containing MgO(001) surfaces will be presented and compared with calculated data. Electron Paramagnetic Resonance (EPR) spectroscopy and low-temperature (5K) Scanning Tunneling Microscopy (STM) has been applied to characterize single gold atoms, as well as color centers formed by electron bombardment, on the surface of MgO(001) thin films. The interaction of Au atoms and clusters with surface color centers has been monitored with infrared spectroscopy using CO as a probe for the charge state of gold particles. For single atoms and small clusters adsorbed onto color centers the observed redshift of the CO stretching frequency in comparison to CO adsorbed on neutral Au clusters is indicative for negatively charged entities. However, an even larger redshift is observed for CO on single Au atoms adsorbed on regular MgO sites. The origin of this unusual behavior will be discussed.