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O: Oberflächenphysik
O 27: Organische Dünnschichten I
O 27.4: Talk
Thursday, March 27, 2003, 12:00–12:15, HSZ/02
Vibrational and structural properties of the perylene/Ag(111) interface: A quasi-liquid molecular layer — •M. Eremtchenko1, S. Döring1, J.A. Schaefer1, and F.S. Tautz2 — 1Institut für Physik, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau — 2School of Engineering and Science, International University Bremen, PF 750561, 28725 Bremen
We report an investigation of the interface of perylene with the Ag(111) surface. Low energy electron diffraction data (LEED) disclose the structure of perylene monolayers: an incommensurate, close-packed and orientated superstructure, in which individual molecules are orientationally disordered and mobile. Further investigation of this interface with scanning tunnelling microscopy (STM) reveals an imaging mechanism in which a tip-suspended molecule systematically probes the surface corrugation potential and regularly locks into specific adsorption sites during scanning. The interaction of perylene with the substrate is investigated by high resolution electron energy loss spectroscopy (HREELS) in the vibrational and electronic energy loss regimes. We find the existence and weak activity of a local molecular reaction centre. Finally, implications of the weak interaction for the growth process are reported: an early transition (after 2 to 3 monolayers) from two to three dimensional growth and, on annealing to 420 K, dewetting or re-orientation of the molecules are observed.