Deceptive orbital confinement at edges and pores of carbon-based 1D and 2D nanoarchitectures

• Published in: Nature communications Vol. 15; no. 1; pp. 1062 - 9
• Main Authors: Piquero-Zulaica, Ignacio, Corral-Rascón, Eduardo, Diaz de Cerio, Xabier, Riss, Alexander, Yang, Biao, Garcia-Lekue, Aran, Kher-Elden, Mohammad A., Abd El-Fattah, Zakaria M., Nobusue, Shunpei, Kojima, Takahiro, Seufert, Knud, Sakaguchi, Hiroshi, Auwärter, Willi, Barth, Johannes V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05.02.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 147/136; 147/138; 147/3; 639/301/357/551; 639/766/119/1000/1018; 639/925/357/995; Carbon; Catalysis; Conduction bands; Confinement; Decay; Electronic structure; Graphene; Humanities and Social Sciences; Microscopy; Molecular orbitals; multidisciplinary; Nanomaterials; Nanoribbons; Nanotechnology; Orbit decay; Pores; Scanning tunneling microscopy; Science; Science (multidisciplinary); Spectroscopy; Spectrum analysis; Wave functions
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-45138-w

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. 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 and is important for their use in catalysis and sensing applications. The apparent electronic confinement at nanographene boundaries in scanning tunneling microscopy/spectroscopy is often misinterpreted. Here, the authors explain this phenomenon in terms of the decay of frontier orbitals and confinement at the edges of graphene nanoribbons and pores in nanoporous graphene.