Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 96: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures VI

O 96.3: Vortrag

Donnerstag, 15. März 2018, 15:30–15:45, MA 004

On-surface synthesis of Si-porphyrins — •Aleksandr Baklanov, Manuela Garnica, Knud Seufert, and Willi Auwärter — Physik Department E20, Technische Universität München, James Franck Str. 1, 85748 Garching, Germany

On-surface synthesis of non-metal porphyrins is insufficiently explored, although it could open up a possibility to investigate new complexes. Specifically, silicon porphyrins have attracted attention due to their interesting structure and properties [1]. Here we report silicon functionalized tetraphenylporphyrin (Si-TPP) molecules synthesized on a Ag(100) single crystal surface at room temperature in UHV conditions. Self-assembly and electronic properties of Si-TPP were probed by scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoelectron (XP) spectroscopy. The N1s XP spectrum of 2H-TPP contains two peaks corresponding to imminic and pyrrolic nitrogen species, whereas in the Si-TPP case only one peak is observed, indicating that all four nitrogen atoms in the macrocycle are chemically identical. A similar behavior is typical for metalloporphyrins [2]. The C1s signal is not affected by the incorporation of Si in the macrocycle. In STM, Si-TPP can be clearly distinguished from 2H-TPP species by additional protrusions at negative sample bias voltages. Furthermore, STS indicates a change of the 2H-TPP LUMO with the Si-complexation.

[1] J. A. Cissell et al., J. Am. Chem. Soc. 127, 12212 (2005).

[2] A. C. Papageorgiou et al., J. Phys. Chem. C 120, 8751 (2016).