An organic array of quantum corrals modulated by the gold herringbone electronic superlattice

Abstract

The periodic herringbone reconstruction on the surface of Au(111) consists of alternating face-centered-cubic (fcc) and hexagonal-closed-packed (hcp) sites separated by dislocation lines and elbows. This well-known arrangement acts as an electronic superlattice for surface-state electrons, creating a mini-gapped band structure with a modulated electronic density. This rich and fascinating geometrical and electronic landscape has countless times served as a platform for molecular self-assembly and on-surface synthesis of carbon-based nanoarchitectures as well as a template for 2D material growth. In this work, we fabricated a long-range ordered organic quantum corral (QC) array via the self-assembly of 1,3,5-benzenetribenzoic acid molecules onto the herringbone reconstructed Au(111) surface. The periodicity of this QC array is nearly half the one of the underlying Au herringbone reconstruction, enabling us to study the delicate interplay between the two potential landscapes by allowing the selective formation and electronic modulation of QCs both on hcp and fcc sites. Scanning tunneling microscopy/spectroscopy (STM/STS) can probe such local differences in the first partially confined state and finds that not only the energy onset of the surface state electrons is influenced but also the modulation of the shallow herringbone potential contributes to the newly formed band structure. This is confirmed by angle-resolved photoemission spectroscopy (ARPES), where the interplay of the periodic potentials introduced by the organic QC array and herringbone reconstruction results in the formation of a distinct surface state band structure. These results are corroborated and intuitively understood with electron-plane-wave expansion (EPWE) simulations. Our work shows that combined molecular and non-organic patterning can serve as a promising tool to macroscopically tune the electronic properties of metal surfaces in a controllable manner.