Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.17: Poster

Dienstag, 15. März 2011, 18:30–22:00, P4

Spatially resolved electron-vibration coupling in an organic charge transfer salt on Au(111) — •Isabel Fernandez-Torrente, Katharina J. Franke, and Jose Ignacio Pascual — Institut für Experimentalphysik, Freie Universität Berlin

Understanding the process of vibrational excitations in molecules is a subject of fundamental importance in potential organic-based device application due to the crucial influence vibrations have in the electronic transport properties. We have measured the vibrational properties of the acceptor molecule TCNQ embedded in a self-assembled layer with TTF, a charge donor. We find that TCNQ hosts, upon charge transfer, an unpaired spin in its Lowest Unoccupied Molecular Orbital (LUMO). This state is demonstrated by the observation of a Kondo resonance. Besides Kondo, this spin is coupled to vibrational modes of the TCNQ that induce a splitting of the Kondo resonance in vibrational sidebands, each one consisting on a peak and a step. While the steps correspond to a pure inelastic process, the peaks have an elastic character (i.e. vibrations excited through the resonant Kondo channel), demonstrated by the quenching of intensity of the central Kondo peak with increasing number of excited vibrations. The vibrations are spatially localized in particular regions of the molecule. The analysis of the STS elastic peaks and STS maps taken on individual TCNQ molecules allow us to resolve with submolecular precision the strength of the electron-phonon coupling and its specific location.