Near Fermi Superatom State Stabilized by Surface State Resonances in a Multiporous Molecular Network

Abstract

Two-dimensional honeycomb molecular networks confine a substrate’s surface electrons within their pores, providing an ideal playground to investigate the quantum electron scattering phenomena. Besides surface state confinement, laterally protruding organic states can collectively hybridize at the smallest pores into superatom molecular orbitals. Although both types of pore states could be simultaneously hosted within nanocavities, their coexistence and possible interaction are unexplored. Here, we show that these two types of pore states do coexist within the smallest nanocavities of a two-dimensional halogen-bonding multiporous network grown on Ag(111) studied using a combination of scanning tunneling microscopy and spectroscopy, density functional theory calculations, and electron plane wave expansion simulations. We find that superatom molecular orbitals undergo an important stabilization when hybridizing with the confined surface state, following the significant lowering of its free-standing energy. These findings provide further control over the surface electronic structure exerted by two-dimensional nanoporous systems.

Engineering quantum states and electronic landscapes through surface molecular nanoarchitectures

“…In particular, electronic scattering and confinement effects should be transferable to image potential states that are accessible via STS or 2PPE techniques (Echenique et al, 2004;Schouteden and Van Haesendonck, 2012;Niesner and Fauster, 2014;Rejali et al, 2022). Additionally, network modified 2DEGs have recently been proposed to play a key role in the stabilization and the significant energy down-shifting of superatom molecular orbitals (Kawai et al, 2021). These states of molecular origin feature a localized and simultaneously high DOS at small pores (∼0.5 nm wide) that could be useful in future applications (Zhang, Björk et al, 2016;Hieulle et al, 2018;Moreno et al, 2018;Kawai et al, 2021).…”

“…Additionally, network modified 2DEGs have recently been proposed to play a key role in the stabilization and the significant energy down-shifting of superatom molecular orbitals (Kawai et al, 2021). These states of molecular origin feature a localized and simultaneously high DOS at small pores (∼0.5 nm wide) that could be useful in future applications (Zhang, Björk et al, 2016;Hieulle et al, 2018;Moreno et al, 2018;Kawai et al, 2021).…”

Multiple molecular interactions between alkyl groups and dissociated bromine atoms on Ag(111)

“…On-surface molecular self-assembly relies on spontaneous processes based on intermolecular interactions, such as van der Waals forces, [1][2][3] dipole interactions, 4,5 hydrogen bonding, [6][7][8][9] and halogen bonding. [10][11][12][13][14] These non-covalent interactions are inherently complex and intricate. Furthermore, local deformations and charge redistribution in molecules are affected by molecule-substrate interactions, resulting in a specific adsorption geometry of each unit in the assembly.…”

High-Yield Production of Quantum Corrals in a Surface Reconstruction Pattern

“…On-surface chemical reactions , have recently developed into a promising way to prepare the otherwise inaccessible architectures with desired geometry as impressively exampled by the synthesis of graphene nanoribbons with atomically precise edges and well-defined width. , However, thermally activated on-surface reactions always lead to high defect density, small domain size, and limited regioselectivity. , For covalently linked organic nanopores and cycles, both entropy and in-plane strain effects coupled with competitive reaction pathways result in an ultralow yield and unwanted byproducts. , Long-range ordered two-dimensional (2D) nanoporous polymers in mesoscale lateral extension have been realized through topochemical photopolymerization, , but the number of known monomers with reactive packing is very limited. − Moreover, the realization of QCs in organic nanocavities on the noble metal surface requires that the pore size should be comparable to the Fermi wavelength of 2D electron gas. , These stringent requirements give rise to few experimental realizations of stable QCs in organic frameworks. − …”

“…26−28 Moreover, the realization of QCs in organic nanocavities on the noble metal surface requires that the pore size should be comparable to the Fermi wavelength of 2D electron gas. 29,30 These stringent requirements give rise to few experimental realizations of stable QCs in organic frameworks. 31−34 To this end, we use hexabromobenzene (HBB) and Au(111) as the precursor and substrate to construct robust QCs with high-yield production (Scheme 1).…”