SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 22: Poster Session: Organic Molecules on Inorganic Substrates I

O 22.6: Poster

Montag, 27. März 2023, 18:00–20:00, P2/EG

Decoupling of vanadyl-naphthalocyanine from a metal substrate by monolayer MoS2 — •J. Rika Simon, Gaël Reecht, Christian Lotze, and Katharina J. Franke — Fachbereich Physik, Freie Universität Berlin, Germany

Phthalocyanines with metal centres are well known for their relative stability on surfaces and are of interest because of the spin they can carry in their metal centres. On metal surfaces, the molecular electronic states are often hydridised with the metal underneath, making it difficult to observe fine details in the electronic structure and inelastic excitations. Using monolayers of semiconducting transition-metal dichalcogenides (TMDCs) as a decoupling layer on top of metal surfaces is a well-established way to allow access to highly resolved dI/dV spectra. Here, we use scanning tunnelling microscopy (STM) to probe the properties of vanadyl-naphthalocyanine (VONc) on MoS2/Au(111). We observe VONc with molecular centres appearing with different apparent heights, which can be interpreted as different configurations of the central oxygen atom sitting on top or below the molecular macrocycle, as observed previously on the closely related molecule vanadyl-phthalocyanine (VOPc) [1,2]. Additionally, we see sharp molecular states in the semiconducting band gap, which are affected by the perturbation potential of the tip [3], causing them to shift in energy across the VONc molecules.

[1] L. Malavolti et al., Nano Lett. 18, 7955 – 7961 (2018)

[2] K. Kaiser et al., ACS Nano 13, 6947 – 6954 (2019)

[3] N. Krane et al., PRB 100, 035410 (2019)