Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 5: Organic-Inorganic Hybrid Systems and Organic Films I

O 5.7: Talk

Monday, March 20, 2017, 12:00–12:15, WIL A317

Interaction of free-base tetraphenylpoprhyrin with magnesium oxide: Inluence of MgO morphology on metalation — •Gianluca Di Filippo, Andrej Classen, Rebecca Pöschel, and Thomas Fauster — Lehrstuhl für Festkörperphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 7, 91058, Erlangen, Germany

Using x-ray photoemission spectroscopy we investigated the self-metalation of free-base tetraphenylporphyrin (2HTPP) on thin MgO(100) films on Ag(100). The deposition of one monolayer 2HTPP on MgO results in the formation of magnesium(II) tetraphenylporphyrin (MgTPP) at room temperature. We demonstrate that the efficiency of the reaction drastically depends on the morphology of the oxide layers. A thin MgO/Ag(100) film grown at 393 K presents a high island density [1]. Partial metalation of 1 ML 2HTPP onto this surface is already observed at a nominal MgO thickness well below 1 ML. The increase of the MgO amount leads to the progressive increase of the number of metalated molecules. Larger islands are obtained at a growth temperature of 573 K [1]. On such a substrate the metalation efficiency is consistently reduced so that partial metalation is only observed for a MgO nominal thickness above 1 ML. We ascribe these results to the fact that MgTPP formation takes place through the hydroxilation of steps and defects on the MgO surface [2], as confirmed by the increase of the OH signal in the O 1s line.