Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 8: Metal Substrates: Adsorption of Organic/Bio Molecules I
O 8.10: Talk
Monday, February 25, 2008, 14:15–14:30, MA 041
Electron-phonon coupling in C60 as revealed by scanning tunneling spectroscopy — •Katharina J. Franke1, Thomas Frederiksen2, Sergio Monturet3, Gunnar Schulze1, Andres Arnau2, Nicolas Lorente4, and Jose Ignacio Pascual1 — 1Freie Universität Berlin, Berlin, Germany — 2Donostia International Physics Center, Donostia, Spain — 3Universite Paul Sabatier, Toulouse, France — 4Centro de Investigaciones en Nanociencia y Nanotecnologia, Bellaterra, Spain
Electron-phonon coupling is of major importance for charge transport through single molecule tunneling junctions. In most experimental implementations of molecular junctions the electronic coupling of the molecular orbitals with substrate states leads to a significant broadening, thus obscuring electron-phonon coupling effects. Here, we investigate the electronic structure of single C60 molecules adsorbed on top of a self-assembled pattern of alternating tetraphenyladamantane and C60. Scanning tunnelling spectroscopy reveals that these molecules exhibit properties similar to the free molecule, such as a large gap of 3.7 eV and a narrow LUMO resonance of only ≈60 meV line width. The LUMO resonance is followed by a broad weaker peak at about 240 meV higher energy. By density functional calculations including the Jahn-Teller effect, we show that this broad feature is induced by a complex coupling of the C60 vibrational eigenmodes with the LUMO resonance.