Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 41: Inorganic/Organic Interfaces
O 41.42: Poster
Tuesday, March 17, 2015, 18:15–21:00, Poster B
Probing non-planar porphyrin molecules with nc-AFM — Florian Albrecht1, •Felix Bischoff2, Yuanqin He2, Willi Auwärter2, Johannes Barth2, and Jascha Repp1 — 1Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany — 2Technische Universität München, Department of Physics, E20, 85748 Garching, Germany
Small amplitude, nc-AFM has been established as advanced imaging tool in scanning probe microscopy. Its capability to determine molecular bond characteristics allows a direct identification of molecular structures, conformation and changes therein caused by chemical reactions. However nc-AFM investigations of surface-confined molecules have so far mainly been applied to planar species. Herein we investigate non-planar porphyrins on metal substrates and compare free-base to metalated species. The substrate-induced saddle-shape conformation and the orientation of molecular moieties can be clearly visualized. However, in a direct comparison of 2H-TPP to CuTPP on Cu(111), a flattening of the macrocycle of Cu-TPP, as reported in literature, could not be unambiguously confirmed. On the other hand, a conformational change of the macrocycle caused by the formation of an SAT-complex can clearly be observed for 2H-TPCN on Ag(111). nc-AFM therefore provides the potential to identify (and quantify) the orientation of sub-molecular units within non-planar molecules in real space and might present a possible alternative to space averaging methods such as NEXAFS.