Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Organic/bio Molecules on Metal Surfaces II
O 18.5: Vortrag
Montag, 11. März 2013, 17:00–17:15, H38
Measuring the electron correlation energy between organic molecules and metal surfaces — •Christian Wagner1,2, Norman Fournier1,2, Victor G. Ruiz3, Alexandre Tkatchenko3, F. Stefan Tautz1,2, and Ruslan Temirov1,2 — 1Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany — 2JARA-Fundamentals of Future Information Technology — 3Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195, Berlin, Germany
Van der Waals forces have to be considered in any quantitatively correct picture of molecular adsorption. Experimental determination of the energy related to long-range correlation effects is, however, difficult. A measured binding energy is always the result of many contributions, including chemical interactions and Pauli repulsion. Here, we present a measurement of single-molecule adsorption potentials as a function of molecule-surface separation using a frequency modulated atomic force microscope[1,2]. We decompose the different contributions to the potential by their different decay lengths. By investigating molecules with a naphthalene, perylene and terrylene core respectively (NTCDA, PTCDA, TTCDA) on Au(111), we study the dependency of the correlation energy on the size of the aromatic system. We compare the experimentally obtained adsorption potentials to DFT+van der Waals calculations which include dielectric screening within the metal[3].
[1] N. Fournier et al., Phys. Rev. B 84, 035435 (2011)
[2] C. Wagner et al., Phys. Rev. Lett. 109, 076102 (2012)
[3] V. G. Ruiz et al., Phys. Rev. Lett. 108, 146103 (2012)