Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.34: Poster
Dienstag, 1. April 2014, 18:30–22:00, P1
Temperature induced dehydrogenation and substrate-mediated hydrogen transfer of tetra(p-hydroxyphenyl)porphyrin - a photoelectron spectroscopy study — •Lars Smykalla1, Pavel Shukrynau1, Michael Hietschold1, Carola Mende2, Heinrich Lang2, and Dietrich R. T. Zahn3 — 1Technische Universität Chemnitz, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz, Germany — 2Technische Universität Chemnitz, Institute of Chemistry, Inorganic Chemistry, D-09107 Chemnitz, Germany — 3Technische Universität Chemnitz, Institute of Physics, Semiconductor Physics, D-09107 Chemnitz
We present photoelectron spectroscopy investigations of 5,10,15,20-tetra(p-hydroxyphenyl)porphyrin (H2THPP) molecules adsorbed on Au(111) and Ag(110). Directly after deposition of the molecular layer, coexistence of H2THPP molecules with the cationic form H4THPP is found. Annealing leads to the dissociation of the central hydrogen atoms in the molecules. On Au(111) after annealing to high temperatures, subsequently, both H2THPP and its doubly dehydrogenated form THPP are observed. On the other hand, on the more reactive Ag(110) surface after annealing to 300 ∘C, partial dissociation of the hydroxyl groups followed by diffusion and rebonding of hydrogen to the central nitrogen atoms and with this the formation of a zwitterionic species is found. Furthermore starting at this temperature, on both substrates partial C−H bond breaking at the pyrrole rings is observed, which affects the whole electronic structure of the molecule as shown in the valance band spectra.