The charge states of metal adatoms on surfaces play a crucial role in controlling adsorption and interaction behaviors that underpin surface chemistry and catalysis, yet the atomically synthesis of negatively charged metal atoms remains a significant challenge. Here, we report negatively-charged Ag dimer (Ag_2^(δ-)) arrays assembled on Ag(100) surface through coordination with a polycyclic aromatic hydrocarbon, 8,9-diaza-8a-borabenzo[fg]tetracene (DBT), featuring a doping moiety with N-B-N bonds at zigzag edge. The Ag dimers are stabilized by two DBT monomers through N-Ag-N coordination bonding. In contrast to surface Ag atoms, the coordinated dimers display anionic character, as demonstrated by non-contact atomic force microscopy, Kelvin probe force microscopy, x-ray photoelectron spectroscopy, and density functional theory calculations. Neutral dimers Ag_2^0 can be converted from the coordinated complex by tip-induced detachment of one DBT monomer, and showed markedly higher affinity for CO adsorption, a process that is suppressed on (Ag_2^(δ-)). These findings establish an atomically defined platform for stabilizing and controlling anionic metal centers on metallic surfaces, providing a model system for exploring charge-state effects in surface chemistry.
Zhi-Hao Li#, Jia-Qi Dai#, Guan Luo, Ruo-Ning Li, An-Jing Zhao, Jun-Jie Duan, Yu Ge, Zi-Cong Wang, Wei Ji*, Ting Chen*, Dong Wang and Li-Jun Wan
Abstract:
Atomically thin InTe, a III–VI analogue of InSe, has recently emerged as a promising two-dimensional semiconductor for nanoelectronics, yet the nature of its two-dimensional electron gas (2DEG) has remained experimentally elusive. Here, using scanning tunneling microscopy (STM) combined with quasiparticle interference (QPI) imaging, we present direct evidence of the existence of a 2DEG in monolayer and bilayer InTe. Bias-dependent standing-wave patterns reveal a parabolic conduction-band dispersion in both thicknesses. Quantitative analysis yields a low electron effective mass of 0.241me in monolayer InTe, smaller than that of monolayer InSe/BLG (∼0.27me). In bilayer InTe, interlayer coupling lifts the conduction-band-edge degeneracy, and produces two subbands with effective masses of 0.197me and 0.802me. Density functional theory calculations are in good agreement with the experimental observations. These results establish atomically thin InTe as a promising platform for low-dimensional electronic physics and nanoelectronic applications.
Zhi-Hao Li#, Jia-Qi Dai#, Guan Luo, Ruo-Ning Li, An-Jing Zhao, Jun-Jie Duan, Yu Ge, Zi-Cong Wang, Wei Ji*, Ting Chen*, Dong Wang and Li-Jun Wan
Abstract:
As a fundamental phenomenon in nature, chirality has been extensively studied in molecular structures; however, it remains underexplored at the electronic level. Understanding how structural chirality transfers into electronic states is crucial for uncovering the essence of many chiral effects. In this study, we report the engineering and direct visualization of chiral electronic states within an otherwise planar, achiral hexa- peri -hexabenzocoronene (HBC) framework. By employing atomically precise asymmetric nitrogen doping of HBC through on-surface synthesis, we fabricate a C3 -symmetric triaza-HBC on Au(111). Utilizing high-resolution scanning tunneling microscopy and non-contact atomic force microscopy, we resolve the chiral molecular structure of triaza-HBC confined to the surface, as well as the chiral texture of the resulting interfacial electronic states and its evolution at different energies. Density functional theory calculations reveal that these electronic chiral features arise from the molecule’s intrinsic chiral orbitals, which hybridize strongly with the metal substrate while still retaining their chiral character. This study not only demonstrates a clear transfer of chirality from molecular structure to the electronic landscape but also provides a versatile platform for the rational design of chiral electronic molecules and materials.
Manyu Wang, Chang Li, Bingxian Shi, Shuo Mi, Xiaoxiao Pei, Shumin Meng, Yanyan Geng, Fei Pang, Rui Xu, Li Huang, Wei Ji, Hong-Jun Gao, Peng Cheng*, Le Lei*, and Zhihai Cheng*
Abstract:
Controlling mesoscale and nanoscale material structures and properties through self-organized atomic behavior is essential for atomic-scale manufacturing. However, direct and visual studies of the cross-scale effects of such atomic self-organization on mesoscopic structures remain scarce. Herein, we report the intertwined atomic-nanoscale-mesoscale structures via the intralayer Fe-chains in the sandwich-like layered FePd2Te2 crystal by scanning tunneling microscopy (STM) and atomic force microscopy (AFM). The hierarchical orthogonal corrugated morphologies are directly revealed and attributed to their chain-orientation-determined twinning-domain effect. Both Fe-chains of the middle-sublayer and two kinds of Te atoms of the top-sublayer are further atomically resolved, indicating the critical effects of Pd atoms/voids on the intralayer anisotropic Fe-chains and the interlayer structural alignment. The thermally induced and strain-related structural transitions of the surface layer are further investigated and discussed based on the proposed filling model of Pd-voids by the intralayer Pd atoms. Our work not only provides a deep understanding of this exotic layered magnetic material but also will inspire more perspectives for tailoring its anisotropic atomic-to-mesoscale structures and properties.
Boyu Fu#; Yurou Guan#; Wei Yuan#; Jianqun Geng#; Zhenliang Hao#; Zilin Ruan; Shijie Sun ; Yong Zhang; Wei Xiong; Lei Gao*; Yulan Chen*; Wei Ji*; Jianchen Lu*; Jinming Cai*
Abstract:
Tert-butyl functional groups can modulate the self-assembly behavior of organic molecules on surfaces. However, the precise construction of supramolecular architectures through their controlled thermal removal remains a challenge. Herein, we precisely controlled the removal amount of tert-butyl groups in tetraazaperopyrene derivatives by stepwise annealing on Ag(111). The evolution of 4tBu-TAPP supramolecular self-assembly from the grid-like structure composed of 3tBu-TAPP through the honeycomb network formed by 2tBu-TAPP to the one-dimensional chain co-assembled by tBu-TAPP and TAPP was successfully realized. This series of supramolecular nanostructures were directly visualized by high resolution scanning tunneling microscopy. Tip manipulation and density functional theory calculations show that the formation of honeycomb network structure can be attributed to the van der Waals interactions, N–Ag–N coordination bonds, and weak C–H⋯N hydrogen bonds. Further addition of two tert-butyl groups (6tBu-TAPP) leads to a completely different assembly evolution, due to the fact that the additional tert-butyl groups affect the molecular adsorption behavior and ultimately induce desorption. This work can possibly be exploited in constructing stable and long-range ordered nanostructures in surface-assisted systems, which can also promote the development of nanostructures in functional molecular devices.
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