Mathias SchwendtPhD Student Karl-Franzens-Universität GrazInstitute of Physics – Solid State Theory
G. Di Santo, T. Miletić, M. Schwendt, Y. Zhou, B. M. Kariuki, K. D. M. Harris, L. Floreano, A. Goldoni, P. Puschnig, L. Petaccia, D. Bonifazi
Orbital Mapping of Semiconducting Perylenes on Cu(111) Journal Article
In: J. Chem. Phys. C, vol. 125, pp. 24477-24486, 2021.
Semiconducting O-doped polycyclic aromatic hydrocarbons constitute a class of molecules whose optoelectronic properties can be tailored by acting on the π-extension of the carbon-based frameworks and on the oxygen linkages. Although much is known about their photophysical and electrochemical properties in solution, their self-assembly interfacial behavior on solid substrates has remained unexplored so far. In this paper, we have focused our attention on the on-surface self-assembly of O-doped bi-perylene derivatives. Their ability to assemble in ordered networks on Cu(111) single-crystalline surfaces allowed a combination of structural, morphological, and spectroscopic studies. In particular, the exploitation of the orbital mapping methodology based on angle-resolved photoemission spectroscopy, with the support of scanning tunneling microscopy and low-energy electron diffraction, allowed the identification of both the electronic structure of the adsorbates and their geometric arrangement. Our multi-technique experimental investigation includes the structure determination from powder X-ray diffraction data for a specific compound and demonstrates that the electronic structure of such large molecular self-assembled networks can be studied using the reconstruction methods of molecular orbitals from photoemission data even in the presence of segregated chiral domains.
C. Metzger, M. Graus, M. Grimm, G. Zamborlini, V. Feyer, M. Schwendt, D. Lüftner, P. Puschnig, A. Schöll, F. Reinert
In: Phys. Rev. B, vol. 101, iss. 16, pp. 165421, 2020.
In recent years, the method of orbital tomography has been a useful tool for the analysis of a variety of molecular systems. However, the underlying plane-wave final state has been largely expected to be applicable to planar molecules only. Here, we demonstrate on photoemission data from the molecule C60 adsorbed on Ag(110) that it can indeed be a valid approximation for truly three-dimensional molecules at a metal-organic interface. A comparison of the experimental data supported by density functional theory (DFT) calculations of the full interface and simulations of the photoemission process with a more exact final state enables the determination of the adsorption geometry and orientation of the C60 molecules in a monolayer on the Ag(110) surface. Additionally, charge transfer into the molecules is used to confirm the lifting in degeneracy of the t1u molecular orbitals as predicted by DFT calculations.