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O: Fachverband Oberflächenphysik
O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)
O 58.56: Poster
Mittwoch, 28. März 2012, 18:15–21:45, Poster B
Vibronic states of Br4TPP porphyrines on a Cu3N insulating film — •Martina Corso1, Jingcheng Li1, Zechao Yang1, Christian Lotze1, Anna Strozecka1, Lena Kaufmann2, Max Kerbs2, Arno Wiehe2, Christoph A. Schalley2, Katharina Franke1, and Jose Ignacio Pascual1 — 1Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
Insulating thin films grown on metal surfaces decouple adsorbates from the electron density of the underlaying substrate. In this work we use low temperature STM to study the vibronic states of tetra(4-bromophenyl)porphyrin (Br4TPP) molecules decoupled from a Cu(110) surface by a single copper nitride layer (Cu3N). Differential conductance spectra (dI/dV) taken on isolated Br4TPP show that two types of molecules coexist on the surface, probably due to a different local adsorption environment. They preserve the same electronic structure but shifted of 350 meV. A series of equally spaced peaks (∼ 170 meV) corresponding to vibronic states appears in the LUMO of Br4TPP measured in dI/dV spectra. The detection of this vibronic progression, not observed on Cu(110), is enabled by the extended lifetime of the transient charged states of individual Br4TPP which is seven times larger on copper nitride than on the bare metal.