Our recent progress in the fabrication of FeSe and KxFe2_ySe2 ultra thin films and the understanding of their superconductivity properties is reviewed. The growth of high-quality FeSe and KxFe2_ySe2 films is achieved ...Our recent progress in the fabrication of FeSe and KxFe2_ySe2 ultra thin films and the understanding of their superconductivity properties is reviewed. The growth of high-quality FeSe and KxFe2_ySe2 films is achieved in a well controlled manner by molecular beam epitaxy. The high-quality stoichiometric and superconducting crystalline thin films allow us to investigate the intrinsic superconductivity properties and the interplay between the superconductivity and the film thickness, the local structure, the substrate, and magnetism. In situ low-temperature scanning tunneling spectra reveal the nodes and the twofold symmetry in FeSe, high-temperature superconductivity at the FeSe/SrTiO3 interface, phase separation and magnetic order in KxFe2_ySe2, and the suppression of superconductivity by twin boundaries and Fe vacancies. Our findings not only provide fundamental information for understanding the mechanism of unconventional superconductivity, but also demonstrate a powerful way of engineering superconductors and raising the transition temperature.展开更多
Cell adhesion processes are governed by the nanoscale arrangement of the extracellular matrix （ECM）, being more affected by local rather than global concentrations of cell adhesive ligands. In many cell-based studie...Cell adhesion processes are governed by the nanoscale arrangement of the extracellular matrix （ECM）, being more affected by local rather than global concentrations of cell adhesive ligands. In many cell-based studies, grafting of dendrimers on surfaces has shown the benefits of the local increase in concentration provided by the dendritic configuration, although the lack of any reported surface characterization has limited any direct correlation between dendrimer disposition and cell response. In order to establish a proper correlation, some control over dendrimer surface deposition is desirable. Here, dendrimer nanopatterning has been employed to address arginine-glycine-aspartic acid （RGD） density effects on cell adhesion. Nanopatterned surfaces were fully characterized by atomic force microscopy （AFM）, scanning tunneling microscopy （STM） and X-ray photoelectron spectroscopy （XPS）, showing that tunable distributions of cell adhesive ligands on the surface are obtained as a function of the initial dendrimer bulk concentration. Cell experiments showed a clear correlation with dendrimer surface layout： Substrates presenting regions of high local ligand density resulted in a higher percentage of adhered cells and a higher degree of maturation of focal adhesions （FAs）. Therefore, dendrimer nano- patterning is presented as a suitable and controlled approach to address the effect of local ligand density on cell response. Moreover, due to the easy modification of dendrimer peripheral groups, dendrimer nanopatterning can be further extended to other ECM ligands having density effects on cells.展开更多
The template-directed assembly of planar pentacene molecules on epitaxial graphene grown on Ru（0001） （G/Ru） has been investigated by means of low-temperature scanning tunneling microscopy （STM） and density funct...The template-directed assembly of planar pentacene molecules on epitaxial graphene grown on Ru（0001） （G/Ru） has been investigated by means of low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM experiments find that pentacene adopts a highly selective and dispersed growth mode in the initial stage. By using DFT calculations including van der Waals interactions, we find that the configuration with pentacene adsorbed on face-centered cubic （fcc） regions of G/Ru is the most stable one, which accounts for the selective adsorption at low coverage. Moreover, at high coverage, we have successfully controlled the molecular assembly from amorphous, local ordering, to long-range order by optimizing the deposition rate and substrate temperature.展开更多
We report the first atomically resolved scanning tunneling microscope （STM） imaging in a water-cooled magnet （WM）, for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM f...We report the first atomically resolved scanning tunneling microscope （STM） imaging in a water-cooled magnet （WM）, for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance （NMR）. This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world＇s flagship magnet, producing the strongest steady magnetic field.展开更多
Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anch...Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anchored on the Au（111） surface to efficiently collect and pin hydrogen molecules. A two-dimensional （2D） molecular hydrogen cluster is formed around the MnPc. The hydrogen cluster exhibits bias-dependent topography and spatial-dependent conductance spectra, which are rationalized by the exponentially decreasing threshold energy with distance from the central MnPc to activate the motion of the H2 molecules. This exponential drop reveals an interfacial phase behavior in the 2D cluster.展开更多
The precise localization of organic molecules in controllable positions is an important step towards constructing functional nanostructures via the bottom-up strategy. Herein, supramolecularly organized C70-fullerene ...The precise localization of organic molecules in controllable positions is an important step towards constructing functional nanostructures via the bottom-up strategy. Herein, supramolecularly organized C70-fullerene assemblies on macrocycle-modified surfaces were investigated using scanning tunneling microscopy （STM） in combination with theoretical calculations. The results revealed that an up-assembly of C70-fullerene adlayers was successfully formed on top of the bottom macrocycle arrays. Density functional theory （DFT） calculations confirmed that the macrocycle networks along with the co-adsorbed solvent 1-phenyloctane served as a selective template for trapping C70-fullerene molecules in the spectral sites and acted as a support for the C70-fullerene molecules. The periodical distribution of the C70-fullerene molecules should facilitate understanding of the strong dependence of the arrangement of C70-fullerene upon the specific interactions （apart from spatial recognition） derived from modification of the sub-monolayers.展开更多
The precise control of the conformations of biomolecules adsorbed on a surface at the single-molecule level is significant. However, it remains a huge challenge because of the complex structure and conformation divers...The precise control of the conformations of biomolecules adsorbed on a surface at the single-molecule level is significant. However, it remains a huge challenge because of the complex structure and conformation diversity of biomolecules. Herein, a ＂nanopore-confined recognition＂ strategy is proposed to manipulate the adsorption of individual valinomycin molecules at room temperature through precise design of functionalized conjugated macrocycle （CPN8） supramolecular nanopores with complementary architectures and binding sites. We revealed that CPN8 prefers to selectively recognizing valinomycin with complementary architecture because of the strong synergistic interactions between the isopropyl groups of valinomycin and the amino groups of CPN8, with valinomycin- highly oriented pyrolytic graphite （HOPG） interactions. Our perspectives at the single-molecule level will provide valuable insights to improve the design of supramolecular nanopores for conformation-selective recognition of non-conjugated molecules.展开更多
For the design and optimization of functional peptides, unravelling the structures of individual building blocks as well as the properties of the ensemble is paramount. TI＇R1, derived from human transthyretin, is a f...For the design and optimization of functional peptides, unravelling the structures of individual building blocks as well as the properties of the ensemble is paramount. TI＇R1, derived from human transthyretin, is a fibril-forming peptide implicated in diseases such as familial amyloid polyneuropathy and senile systemic amyloidosis. The functional peptide TTR1-RGD, based on a TFR1 scaffold, was designed to specifically interact with cells. Here, we used scanning tunneling microscopy （STM） to analyze the assembly structures of TTRl-related peptides with both the reverse sequence and the modified forward sequence. The site- specific analyses show the following： i） The TIR1 peptide is involved in assembly, nearly covering the entire length within the ordered [3-sheet structures, ii） For TTR1-RGD peptide assemblies, the TTR1 motif forms the ordered [3-sheet while the RGDS motif adopts a flexible conformation allowing it to promote cell adhesion. The key site is clearly identified as the linker residue Gly13. iii） Close inspection of the forward and reverse peptide assemblies show that in spite of the difference in chemistry, they display similar assembling characteristics, illustrating the robust nature of these peptides, iv） Glycine linker residues are included in the ^-strands, which strongly suggests that the sequence could be optimized by adding more linker residues. These garnered insights into the assembled structures of these peptides help unravel the mechanism driving peptide assemblies and instruct the rational design and optimization of sequence- programmed peptide architectures.展开更多
The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneli...The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneling microscopy. Anomalous moir6 superstructures composed of well-defined linear periodic modulations have been observed. We report here on comprehensive and detailed studies of these particular moir6 patterns present in the graphene topography revealing that, in certain conditions, the growth can occur on the oxygen-induced reconstructed copper surface and not directly on the oriented （111） copper film as expected.展开更多
High quality thin films of topological insulators （TI） such as Bi2Se3 have been successfully synthesized by molecular beam epitaxy （MBE）. Although the surface of MBE films can be protected by capping with inert ma...High quality thin films of topological insulators （TI） such as Bi2Se3 have been successfully synthesized by molecular beam epitaxy （MBE）. Although the surface of MBE films can be protected by capping with inert materials such as amorphous Se, restoring an atomically clean pristine surface after decapping has never been demonstrated, which prevents in-depth investigations of the intrinsic properties of TI thin films with ex situ tools. Using high resolution scanning tunneling microscopy/spectroscopy （STM/STS）, we demonstrate a simple and highly reproducible Se decapping method that allows recovery of the pristine surface of extremely high quality Bi2Se3 thin films grown and capped with Se in a separate MBE system then exposed to the atmosphere during transfer into the STM system. The crucial step of our decapping process is the removal of the surface contaminants on top of amorphous Se before thermal desorption of Se at a mild temperature （-210 ~C）. This effective Se decapping process opens up the possibility of ex situ characterizations of pristine surfaces of interesting selenide materials and beyond using cutting-edge techniques.展开更多
Mass-selected anionic cobalt clusters of two different sizes （Co2 and Co13） were deposited onto ultrathin NaC1 films grown on an Au（111） substrate. Using scanning tunneling microscopy experiments and density funct...Mass-selected anionic cobalt clusters of two different sizes （Co2 and Co13） were deposited onto ultrathin NaC1 films grown on an Au（111） substrate. Using scanning tunneling microscopy experiments and density functional theory simulations, we show that the deposited Co2 cluster dissociates and that the resulting Co atoms dope the NaCI surface by substituting Na ions. In contrast, the larger Co13 cluster does not dissociate and remains stable on top of the NaC1 film. The size- dependent fragmentation of clusters is an important aspect in the understanding of the chemical interaction between size-selected small aggregates of atoms and supporting surfaces.展开更多
Si dangling bonds at the interface of quasi-free-standing monolayer graphene （QFMLG） are known to act as scattering centers that can severely affect carrier mobility Herein, we investigate the atomic and electronic ...Si dangling bonds at the interface of quasi-free-standing monolayer graphene （QFMLG） are known to act as scattering centers that can severely affect carrier mobility Herein, we investigate the atomic and electronic structure of Si dangling bonds in QFMLG using low-temperature scanning tunneling microscopy/ spectroscopy （STM/STS）, atomic force microscopy （AFM）, and density functional theory （DFT） calculations. Two types of defects with different contrast were observed on a flat graphene terrace by STM and AFM; in particular, their STM contrast varied with the bias voltage. Moreover, these defects showed characteristic STS peaks at different energies, 1.1 and 1.4 eV. The comparison of the experimental data with the DFT calculations indicates that the defects with STS peak energies of 1.1 and 1.4 eV consist of clusters of three and four Si dangling bonds, respectively. The relevance of the present results for the optimization of graphene synthesis is discussed.展开更多
On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic...On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic, magnetic, or catalytic properties. This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds, which prevents the ripening of defects. We show here that extended materials can be produced by a controlled co-deposition process. In particular, co-deposition of quinoid zwitterion molecules with iron atoms on a Ag（111） surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds. This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.展开更多
基金supported by the National Natural Science Foundation of Chinathe National Basic Research Program of China
文摘Our recent progress in the fabrication of FeSe and KxFe2_ySe2 ultra thin films and the understanding of their superconductivity properties is reviewed. The growth of high-quality FeSe and KxFe2_ySe2 films is achieved in a well controlled manner by molecular beam epitaxy. The high-quality stoichiometric and superconducting crystalline thin films allow us to investigate the intrinsic superconductivity properties and the interplay between the superconductivity and the film thickness, the local structure, the substrate, and magnetism. In situ low-temperature scanning tunneling spectra reveal the nodes and the twofold symmetry in FeSe, high-temperature superconductivity at the FeSe/SrTiO3 interface, phase separation and magnetic order in KxFe2_ySe2, and the suppression of superconductivity by twin boundaries and Fe vacancies. Our findings not only provide fundamental information for understanding the mechanism of unconventional superconductivity, but also demonstrate a powerful way of engineering superconductors and raising the transition temperature.
文摘Cell adhesion processes are governed by the nanoscale arrangement of the extracellular matrix （ECM）, being more affected by local rather than global concentrations of cell adhesive ligands. In many cell-based studies, grafting of dendrimers on surfaces has shown the benefits of the local increase in concentration provided by the dendritic configuration, although the lack of any reported surface characterization has limited any direct correlation between dendrimer disposition and cell response. In order to establish a proper correlation, some control over dendrimer surface deposition is desirable. Here, dendrimer nanopatterning has been employed to address arginine-glycine-aspartic acid （RGD） density effects on cell adhesion. Nanopatterned surfaces were fully characterized by atomic force microscopy （AFM）, scanning tunneling microscopy （STM） and X-ray photoelectron spectroscopy （XPS）, showing that tunable distributions of cell adhesive ligands on the surface are obtained as a function of the initial dendrimer bulk concentration. Cell experiments showed a clear correlation with dendrimer surface layout： Substrates presenting regions of high local ligand density resulted in a higher percentage of adhered cells and a higher degree of maturation of focal adhesions （FAs）. Therefore, dendrimer nano- patterning is presented as a suitable and controlled approach to address the effect of local ligand density on cell response. Moreover, due to the easy modification of dendrimer peripheral groups, dendrimer nanopatterning can be further extended to other ECM ligands having density effects on cells.
基金This work was financially supported by the Ministry of Science and Technology （MOST Nos. 2011CB921702 and 2011CB932700）, National Natural Science Foundation of China （NSFC No. 61222112）, Multilevel Molecular Assemblies： Structure, Dynamics, and Functions （TRR61）, Shanghai Supercomputer Center （SSC）, and Chinese Academy of Sciences （CAS） in China. WAH acknowledges support from the UK Car-Parinello consortium, grant No. EP/F037783/1.
文摘The template-directed assembly of planar pentacene molecules on epitaxial graphene grown on Ru（0001） （G/Ru） has been investigated by means of low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM experiments find that pentacene adopts a highly selective and dispersed growth mode in the initial stage. By using DFT calculations including van der Waals interactions, we find that the configuration with pentacene adsorbed on face-centered cubic （fcc） regions of G/Ru is the most stable one, which accounts for the selective adsorption at low coverage. Moreover, at high coverage, we have successfully controlled the molecular assembly from amorphous, local ordering, to long-range order by optimizing the deposition rate and substrate temperature.
文摘We report the first atomically resolved scanning tunneling microscope （STM） imaging in a water-cooled magnet （WM）, for which extremely harsh vibrations and noise have been the major challenge. This custom WM-STM features an ultra-rigid and compact scan head in which the coarse approach is driven by our newly designed TunaDrive piezoelectric motor. A three-level spring hanging system is used for vibration isolation. Room-temperature raw-data images of graphite with quality atomic resolution were acquired in the presence of very strong magnetic fields, with a field strength up to 27 T, in a 32-mm-diameter bore WM with a maximum field strength of 27.5 T at a power rating of 10 MW, calibrated by nuclear magnetic resonance （NMR）. This record field strength of 27 T exceeds the maximal field strength achieved by the conventional supercon- ducting magnets. Besides, our WM-STM has paved the way to STM imaging using a 45 T, 32-mm-diameter bore hybrid magnet, which is the world＇s flagship magnet, producing the strongest steady magnetic field.
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 51210003 and 11290165）, National Basic Research Program of China （No. 2009CB929103）, TRR61 and Chinese Academy of Sciences.
文摘Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anchored on the Au（111） surface to efficiently collect and pin hydrogen molecules. A two-dimensional （2D） molecular hydrogen cluster is formed around the MnPc. The hydrogen cluster exhibits bias-dependent topography and spatial-dependent conductance spectra, which are rationalized by the exponentially decreasing threshold energy with distance from the central MnPc to activate the motion of the H2 molecules. This exponential drop reveals an interfacial phase behavior in the 2D cluster.
基金This work was supported by the National Basic Research Program of China （Nos. 2016YFA0200700, 2013CB934200, and 2012CB933001） and the National Natural Science Foundation of China （No. 21472029）.
文摘The precise localization of organic molecules in controllable positions is an important step towards constructing functional nanostructures via the bottom-up strategy. Herein, supramolecularly organized C70-fullerene assemblies on macrocycle-modified surfaces were investigated using scanning tunneling microscopy （STM） in combination with theoretical calculations. The results revealed that an up-assembly of C70-fullerene adlayers was successfully formed on top of the bottom macrocycle arrays. Density functional theory （DFT） calculations confirmed that the macrocycle networks along with the co-adsorbed solvent 1-phenyloctane served as a selective template for trapping C70-fullerene molecules in the spectral sites and acted as a support for the C70-fullerene molecules. The periodical distribution of the C70-fullerene molecules should facilitate understanding of the strong dependence of the arrangement of C70-fullerene upon the specific interactions （apart from spatial recognition） derived from modification of the sub-monolayers.
基金Acknowledgements The authors gratefully acknowledged Prof. Chen Wang （National Center for Nanoscience and Technology, China） and Prof. Guocong Guo （Fujian Institute of Research on the Structure of Matter, CAS） for their helpful discussions and advice. This work was supported by the National Basic Research Program of China （No. 2012CB933001）, the National Natural Science Foundation of China （Nos. 51173031, 21472029, 21303202, and 91127043）, the program of Chinese Academy of Sciences （No. YZ201318）, and the Open Project of State Key Laboratory of Supramolecular Structure and Materials （No. sklssm201607）.
文摘The precise control of the conformations of biomolecules adsorbed on a surface at the single-molecule level is significant. However, it remains a huge challenge because of the complex structure and conformation diversity of biomolecules. Herein, a ＂nanopore-confined recognition＂ strategy is proposed to manipulate the adsorption of individual valinomycin molecules at room temperature through precise design of functionalized conjugated macrocycle （CPN8） supramolecular nanopores with complementary architectures and binding sites. We revealed that CPN8 prefers to selectively recognizing valinomycin with complementary architecture because of the strong synergistic interactions between the isopropyl groups of valinomycin and the amino groups of CPN8, with valinomycin- highly oriented pyrolytic graphite （HOPG） interactions. Our perspectives at the single-molecule level will provide valuable insights to improve the design of supramolecular nanopores for conformation-selective recognition of non-conjugated molecules.
文摘For the design and optimization of functional peptides, unravelling the structures of individual building blocks as well as the properties of the ensemble is paramount. TI＇R1, derived from human transthyretin, is a fibril-forming peptide implicated in diseases such as familial amyloid polyneuropathy and senile systemic amyloidosis. The functional peptide TTR1-RGD, based on a TFR1 scaffold, was designed to specifically interact with cells. Here, we used scanning tunneling microscopy （STM） to analyze the assembly structures of TTRl-related peptides with both the reverse sequence and the modified forward sequence. The site- specific analyses show the following： i） The TIR1 peptide is involved in assembly, nearly covering the entire length within the ordered [3-sheet structures, ii） For TTR1-RGD peptide assemblies, the TTR1 motif forms the ordered [3-sheet while the RGDS motif adopts a flexible conformation allowing it to promote cell adhesion. The key site is clearly identified as the linker residue Gly13. iii） Close inspection of the forward and reverse peptide assemblies show that in spite of the difference in chemistry, they display similar assembling characteristics, illustrating the robust nature of these peptides, iv） Glycine linker residues are included in the ^-strands, which strongly suggests that the sequence could be optimized by adding more linker residues. These garnered insights into the assembled structures of these peptides help unravel the mechanism driving peptide assemblies and instruct the rational design and optimization of sequence- programmed peptide architectures.
文摘The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneling microscopy. Anomalous moir6 superstructures composed of well-defined linear periodic modulations have been observed. We report here on comprehensive and detailed studies of these particular moir6 patterns present in the graphene topography revealing that, in certain conditions, the growth can occur on the oxygen-induced reconstructed copper surface and not directly on the oriented （111） copper film as expected.
文摘High quality thin films of topological insulators （TI） such as Bi2Se3 have been successfully synthesized by molecular beam epitaxy （MBE）. Although the surface of MBE films can be protected by capping with inert materials such as amorphous Se, restoring an atomically clean pristine surface after decapping has never been demonstrated, which prevents in-depth investigations of the intrinsic properties of TI thin films with ex situ tools. Using high resolution scanning tunneling microscopy/spectroscopy （STM/STS）, we demonstrate a simple and highly reproducible Se decapping method that allows recovery of the pristine surface of extremely high quality Bi2Se3 thin films grown and capped with Se in a separate MBE system then exposed to the atmosphere during transfer into the STM system. The crucial step of our decapping process is the removal of the surface contaminants on top of amorphous Se before thermal desorption of Se at a mild temperature （-210 ~C）. This effective Se decapping process opens up the possibility of ex situ characterizations of pristine surfaces of interesting selenide materials and beyond using cutting-edge techniques.
文摘Mass-selected anionic cobalt clusters of two different sizes （Co2 and Co13） were deposited onto ultrathin NaC1 films grown on an Au（111） substrate. Using scanning tunneling microscopy experiments and density functional theory simulations, we show that the deposited Co2 cluster dissociates and that the resulting Co atoms dope the NaCI surface by substituting Na ions. In contrast, the larger Co13 cluster does not dissociate and remains stable on top of the NaC1 film. The size- dependent fragmentation of clusters is an important aspect in the understanding of the chemical interaction between size-selected small aggregates of atoms and supporting surfaces.
文摘Si dangling bonds at the interface of quasi-free-standing monolayer graphene （QFMLG） are known to act as scattering centers that can severely affect carrier mobility Herein, we investigate the atomic and electronic structure of Si dangling bonds in QFMLG using low-temperature scanning tunneling microscopy/ spectroscopy （STM/STS）, atomic force microscopy （AFM）, and density functional theory （DFT） calculations. Two types of defects with different contrast were observed on a flat graphene terrace by STM and AFM; in particular, their STM contrast varied with the bias voltage. Moreover, these defects showed characteristic STS peaks at different energies, 1.1 and 1.4 eV. The comparison of the experimental data with the DFT calculations indicates that the defects with STS peak energies of 1.1 and 1.4 eV consist of clusters of three and four Si dangling bonds, respectively. The relevance of the present results for the optimization of graphene synthesis is discussed.
文摘On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic, magnetic, or catalytic properties. This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds, which prevents the ripening of defects. We show here that extended materials can be produced by a controlled co-deposition process. In particular, co-deposition of quinoid zwitterion molecules with iron atoms on a Ag（111） surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds. This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.
