Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 8: Metal Substrates: Adsorption of Organic/Bio Molecules I
O 8.11: Talk
Monday, February 25, 2008, 14:30–14:45, MA 041
Electronic and Vibrational Properties of Ce2@C80 Metallofullerenes — •Bert Voigtländer1, Anna Strózecka1, Josef Mysliveček1,2, Kaliappan Muthukumar3, and J.Andreas Larsson3 — 1Institute of Bio- and Nanosystems (IBN 3), and cni – Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany — 2Department of Surface and Plasma Physics, Charles University in Prague — 3Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland
The electron transport properties of the fullerenes have been investigated by the study of the properties of single-molecule STM junctions over an endohedral metallofulerene Ce2@C80 on Cu(111). In comparison to single-molecule STM junctions over C60 molecules the controlled contacts to the metallofullerene show an order-of-magnitude lower conductivity. We ascribe this effect to the encapsulation of metal ions inside the fullerene cage. The STM based inelastic vibrational spectroscopy on Ce2@C80 shows, apart from features related to the cage phonons also a low frequency mode at 9 meV. Based on theoretical calculations of the vibrational structure of the molecule, the feature can be assigned to the movement of Ce-Ce unit. The electronic spectroscopic measurements on Ce2@C80 molecules reveal an unusually high increase in the differential conductance of this molecule at low bias voltages. The experiments indicate that the effect is related to the excitation of highly efficient vibrational modes and not to e.g. to a Kondo resonance that represents another common zero-bias anomaly.