Electronic structure of a subnanometer wide bottom-up fabricated graphene nanoribbon: End states, band gap and dispersion

TL;DR

This study investigates the electronic structure of a precisely fabricated subnanometer graphene nanoribbon using advanced spectroscopy and theoretical calculations, revealing large band gap, dispersion characteristics, and end states unique to finite systems.

Contribution

It provides detailed experimental and theoretical insights into the electronic properties, including end states and a large band gap, of a bottom-up synthesized graphene nanoribbon.

Findings

Large band gap of 5.1 eV identified

Unoccupied non-dispersive end states observed

Electronic dispersion characterized through spectroscopy

Abstract

Angle-resolved two-photon photoemission and high-resolution electron energy loss spectroscopy are employed to derive the electronic structure of a sub-nanometer tomically precise quasi-one-dimensional graphene nanoribbon (GNR) on Au(111). We resolved occupied and unoccupied electronic bands including their dispersion and determined the and gap, which possesses an unexpected large value of 5.1 eV. Supported by density functional theory (DFT) calculations for the idealized infinite polymer and finite size oligomers an unoccupied non-dispersive electronic state with an energetic position in the middle of the band gap of the GNR could be identified. This state resides at both ends of the ribbon (end state) and is only found in the finite sized systems, i.e. the oligomers.