Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 31: Organische Dünnschichten III

O 31.5: Talk

Monday, March 7, 2005, 11:45–12:00, TU EB420

High resolution STM images of the PTCDA/Ag(111) interface — •A. Kraft, M. Rohlfing, and F. S. Tautz — School of Engineering and Science, International University Bremen, Campus Ring 8, D-28759 Bremen, Germany

We present a combined experimental and theoretical investigation of the detailed atomic structure of the interface between 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and Ag(111). The herringbone structure of the PTCDA/Ag(111) interface was imaged in a range of different tunneling conditions with a low-temperature scanning tunneling microscope (T =9K). Experimental images are compared to calculated images based on a density functional study of the complete interface. We use the generalized gradient approximation, localized basis orbitals, and a transfer-matrix formalism to evaluate the local density of states above the surface, which corresponds to the tunneling current (Tersoff-Hamann-theory) We find excellent agreement between experiment and calculations. Implications of our results for the precise structure of the interface are discussed.