Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 20: Focus Session: Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation I
O 20.9: Vortrag
Dienstag, 19. März 2024, 12:45–13:00, HE 101
Deceptive orbital confinement at the edges and pores of carbon-based 1D and 2D nanoarchitectures — •Ignacio Piquero-Zulaica1, Eduardo Corral-Rascón1, Xabier Diaz de Cerio2, Alexander Riss1, Aran Garcia-Lekue2, Hiroshi Sakaguchi3, Willi Auwärter1, and Johannes V. Barth1 — 1Physics Department E20, Technical University of Munich, D-85748 Garching, Germany — 2Donostia International Physics Center (DIPC), E-20018 Donostia-San Sebastian, Spain — 3Institute of Advanced Energy, Kyoto University, 611-0011, Kyoto, Japan
The electronic structure defines the properties of graphene-based nanomaterials. Scanning tunneling microscopy/spectroscopy (STM/STS) experiments on graphene nanoribbons (GNRs), nanographenes and nanoporous graphene (NPG) often determine an apparent electronic orbital confinement into the edges and nanopores, leading to dubious interpretations such as image potential states or super-atom molecular orbitals. Here we show that these measurements are subject to a wave function decay into the vacuum that masks the undisturbed electronic orbital shape. We use Au(111)-supported semiconducting gulf-type GNRs and NPGs as model systems fostering frontier orbitals that appear confined along the edges and nanopores in STS measurements. DFT calculations confirm that these states originate from valence and conduction bands. The deceptive electronic orbital confinement observed is caused by a loss of Fourier components, corresponding to states of high momentum. This effect can be generalized to other 1D and 2D carbon-based nanoarchitectures.
Keywords: Nanoporous graphene; Graphene nanoribbons; Scanning tunneling microscopy/spectroscopy; Electronic properties; Density functional theory