Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 81: Oxide and Insulator Surfaces: Adsorption II

O 81.7: Talk

Wednesday, March 22, 2017, 17:30–17:45, WIL C107

High-resolution photoemission and X-ray absorption spectroscopy of a functionalized porphyrin adsorbed on MgO(100) — •Quratulain Tariq, Matthias Franke, Daniel Wechsler, Hans-Peter Steinrück, and Ole Lytken — Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, 91058 Erlangen, Egerlandstraße 3, Germany

Ultra-thin layers of functional organic molecules on oxide surfaces have a huge scientific and technological potential in molecular electronics. Porphyrins, in particular, represent an interesting class of compounds that can be modified synthetically by variation of the metal center, by attaching different substituents to the macrocycle, or by introduction of specific linker groups for the attachment on surfaces. In present work, a cobalt porphyrin bearing carboxylic groups, 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (CoTCPP), was anchored on MgO(100)/Ag(100) thin films, at room temperature. High-resolution synchrotron radiation photoelectron spectroscopy (SRPES) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy are used to characterize the system, as a function of coverage and temperature. SRPES analysis for different coverages reveals that CoTCPP binds to the surface via formation of bidentate carboxylate. From NEXAFS spectroscopy, it is found that for sub-monolayer coverage, CoTCPP adsorbs almost parallel to the oxide substrate, whereas for monolayer and higher coverages, CoTCPP adsorbs at an angle from the surface plane (with a possible tilt angle of < 45° relative to the surface normal). This project is supported by the DFG through FOR 1878 (funCOS).