Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)

O 58.36: Poster

Wednesday, March 28, 2012, 18:15–21:45, Poster B

Scanning tunneling microscopy and spectroscopy of TMP-TCNQ — •Sandra Perkert¹, Katerina Medjanik¹, Shahab Naghavi², Milan Rudloff³, Vita Solovyeva³, Dennis Chercka⁴, Torsten Methfessel¹, Sergej Nepijko¹, Michael Huth³, Claudia Felser², Martin Baumgarten⁴, Klaus Müllen⁴, Gerd Schönhense¹, and Hans-Joachim Elmers¹ — ¹Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany — ²Institut für Analytische und Anorganische Chemie, Johannes Gutenberg-Universität, 55099 Mainz, Germany — ³Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany — ⁴Max-Planck-Institut für Polymerforschung, 55128 Mainz, Germany

Organic charge transfer (CT) salts are promising new materials for electronic devices. For a better understanding of their interaction with metal substrates we investigate thin films of the well-known acceptor 7,7,8,8-Tetracyanoquinodimethane (TCNQ) and the new synthesized donor Tetramethoxypyrene (TMP) on a W(110) and an Au(111) surface with scanning tunneling microscopy (STM) and spectroscopy (STS). The topographic images show a self-organized structure of TMP and TCNQ on both substrates. On the Au(111) surface TCNQ assembles in an oblique Bravais lattice with different orientational domains. STS measurements reveal the electronic structure of the molecules and the energetic position of HOMO and LUMO. The measured energy gap between HOMO and LUMO is much smaller for the CT-salt TMP-TCNQ than for the pure donor TMP and the pure acceptor TCNQ. These results fit well to theoretical calculations.