Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 14: Organic, polymeric, biomolecular films – also with absorbates I
O 14.3: Talk
Monday, March 23, 2009, 15:30–15:45, SCH A316
Experimental and theoretical NEXAFS investigations of metalloporphyrin films — •Norman Schmidt1, Christian Hub1, Wolfgang Hieringer2, Thomas Strunskus3, and Rainer Fink1 — 1Univ. Erlangen, Physikalische Chemie II, Erlangen, Germany — 2Univ. Erlangen, Theoretische Chemie, Erlangen, Germany — 3C.-A.-Univ. Kiel, Lehrstuhl für Materialverbunde, Kiel, Germany
Metallo-porphyrins are well-known as electron donors in photoinduced electron transfer processes and for their semiconducting properties. They are used as, e.g., dyes, sensitizers, catalysts and in various organo-electronic devices. For improved device design and performance, more detailed knowledge about film morphology and related electronic structure is necessary. In the present study, the electronic structure of thick films of (H2, Mn, Fe, Co, Zn, Sn)-tetraphenyl-porphyrins on Au-plated Si-wafers was investigated using NEXAFS spectroscopy. The obtained N 1s spectra reflect modifications in the electronic structure of the central metal ion interacting with the nitrogen donor functions of the porphyrin ring. Furthermore, the orientation of ultrathin and thick films of ZnTPP and SnTTBPP(OH)2 (TTBPP=tetra(p-tert.butylphenyl)porphyrin) on an Ag(100) single crystal was studied by angle-dependent NEXAFS spectroscopy. In thin films, the porphyrin frame is lying almost flat on the surface, while the phenyl ligands are twisted by about 60 degrees with respect to the surface plane. Corroborating high-level TD-DFT calculations were used to allow more detailed interpretation of the experimental data (this project is funded by the DFG within SFB 583, TP C9).