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Rothe K, Néel N, Kröger J. Unveiling the nature of atomic defects in graphene on a metal surface. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2024; 15:416-425. [PMID: 38655541 PMCID: PMC11035987 DOI: 10.3762/bjnano.15.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 03/18/2024] [Indexed: 04/26/2024]
Abstract
Low-energy argon ion bombardment of graphene on Ir(111) induces atomic-scale defects at the surface. Using a scanning tunneling microscope, the two smallest defects appear as a depression without discernible interior structure suggesting the presence of vacancy sites in the graphene lattice. With an atomic force microscope, however, only one kind can be identified as a vacancy defect with four missing carbon atoms, while the other kind reveals an intact graphene sheet. Spatially resolved spectroscopy of the differential conductance and the measurement of total-force variations as a function of the lateral and vertical probe-defect distance corroborate the different character of the defects. The tendency of the vacancy defect to form a chemical bond with the microscope probe is reflected by the strongest attraction at the vacancy center as well as by hysteresis effects in force traces recorded for tip approach to and retraction from the Pauli repulsion range of vertical distances.
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Affiliation(s)
- Karl Rothe
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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2
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Leitherer S, Brandbyge M, Solomon GC. Electromigration Forces on Atoms on Graphene Nanoribbons: The Role of Adsorbate-Surface Bonding. JACS AU 2024; 4:189-196. [PMID: 38274269 PMCID: PMC10806770 DOI: 10.1021/jacsau.3c00622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 01/27/2024]
Abstract
The synthesis of the two-dimensional (2D) material graphene and nanostructures derived from graphene has opened up an interdisciplinary field at the intersection of chemistry, physics, and materials science. In this field, it is an open question whether intuition derived from molecular or extended solid-state systems governs the physical properties of these materials. In this work, we study the electromigration force on atoms on 2D armchair graphene nanoribbons in an electric field using ab initio simulation techniques. Our findings show that the forces are related to the induced charges in the adsorbate-surface bonds rather than only to the induced atomic charges, and the left and right effective bond order can be used to predict the force direction. Focusing in particular on 3d transition metal atoms, we show how a simple model of a metal atom on benzene can explain the forces in an inorganic chemistry picture. This study demonstrates that atom migration on 2D surfaces in electric fields is governed by a picture that is different from the commonly used electrostatic description of a charged particle in an electric field as the underlying bonding and molecular orbital structure become relevant for the definition of electromigration forces. Accordingly extended models including the ligand field of the atoms might provide a better understanding of adsorbate diffusion on surfaces under nonequilibrium conditions.
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Affiliation(s)
- Susanne Leitherer
- Nano-Science
Center and Department of Chemistry, University
of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Mads Brandbyge
- Department
of Physics, Technical University of Denmark, DK-2800 Kongens
Lyngby, Denmark
| | - Gemma C. Solomon
- Nano-Science
Center and Department of Chemistry, Copenhagen
University, DK-2100 Copenhagen, Denmark
- NNF
Quantum Computing Programme, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
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3
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Rothe K, Néel N, Bocquet ML, Kröger J. Extraction of Chemical Reactivity and Structural Relaxations of an Organic Dye from the Short-Range Interaction with a Molecular Probe. J Phys Chem Lett 2022; 13:8660-8665. [PMID: 36084075 DOI: 10.1021/acs.jpclett.2c02140] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A CO-functionalized atomic force microscope tip is used to locally probe local chemical reactivity and subtle structural relaxations of a single phthalocyanine molecule at different stages of pyrrolic-H abstraction. Spatially resolved vertical force spectroscopy unveils a variation of the maximum short-range attraction between CO and intramolecular sites, which is interpreted as a measure for the local chemical reactivity. In addition, the vertical position of the point of maximum attraction is observed to vary across the molecules. These changes follow the calculated adsorption heights of the probed molecular atoms.
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Affiliation(s)
- Karl Rothe
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Marie-Laure Bocquet
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, F-75005 Paris, France
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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4
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Rothe K, Néel N, Bocquet ML, Kröger J. Quantifying Force and Energy in Single-Molecule Metalation. J Am Chem Soc 2022; 144:7054-7057. [PMID: 35324186 DOI: 10.1021/jacs.2c00900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
An atomic force microscope is used to determine the attractive interaction at the verge of adding a Ag atom from the probe to a single free-base phthalocyanine molecule adsorbed on Ag(111). The experimentally extracted energy for the spontaneous atom transfer can be compared to the energy profile determined by density functional theory using the nudged-elastic-band method at a defined probe-sample distance.
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Affiliation(s)
- Karl Rothe
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Marie-Laure Bocquet
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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5
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Lyu J, Wong ZM, Sun H, Yang SW, Xu GQ. Electric Field-Induced Phase Transition of Nanowires on Germanium(001) Surfaces. J Phys Chem Lett 2022; 13:1063-1068. [PMID: 35075909 DOI: 10.1021/acs.jpclett.1c04020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The manipulation of conductive nanowires (NWs) on semiconductor platforms provides important insights into the fabrication of nanoscale electronic devices. In this work, we directly observed the electric field-induced phase transitions in atomic Au-NWs self-assembled on Ge(001) surfaces using scanning tunneling microscopy (STM). The tunneling electrons and electric fields underneath a STM tip apex can effectively trigger a phase transition in Au-NWs on Ge(001) surfaces. Such phase transitions are associated with a remarkable atomic rearrangement in the Au-NWs, thereby modifying their band structures. Moreover, directly monitoring the dynamic reconstruction of Au-NWs on Ge(001) surfaces helps us to understand the NWs' intricate atomic configurations and their electronic properties. The spatially controlled phase transition at the nanometer scale using STM shows the possibility of modulating NWs' properties at an atomic scale.
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Affiliation(s)
- Jing Lyu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Zicong Marvin Wong
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, # 16-16 Connexis, Singapore 138632, Singapore
| | - Haicheng Sun
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Shuo-Wang Yang
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, # 16-16 Connexis, Singapore 138632, Singapore
| | - Guo Qin Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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Omidian M, Leitherer S, Néel N, Brandbyge M, Kröger J. Electric-Field Control of a Single-Atom Polar Bond. PHYSICAL REVIEW LETTERS 2021; 126:216801. [PMID: 34114869 DOI: 10.1103/physrevlett.126.216801] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/07/2021] [Accepted: 04/12/2021] [Indexed: 06/12/2023]
Abstract
We expose the polar covalent bond between a single Au atom terminating the apex of an atomic force microscope tip and a C atom of graphene on SiC(0001) to an external electric field. For one field orientation, the Au─C bond is strong enough to sustain the mechanical load of partially detached graphene, while for the opposite orientation, the bond breaks easily. Calculations based on density-functional theory and nonequilibrium Green's function methods support the experimental observations by unveiling bond forces that reflect the polar character of the bond. Field-induced charge transfer between the atomic orbitals modifies the polarity of the different electronegative reaction partners and the Au─C bond strength.
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Affiliation(s)
- M Omidian
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - S Leitherer
- Center of Nanostructured Graphene, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - N Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - M Brandbyge
- Center of Nanostructured Graphene, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - J Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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Deghi SE, Fernández-Alcázar LJ, Pastawski HM, Bustos-Marún RA. Current-induced forces in single-resonance systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:175303. [PMID: 33530077 DOI: 10.1088/1361-648x/abe266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
In recent years, there has been an increasing interest in nanoelectromechanical devices, current-driven quantum machines, and the mechanical effects of electric currents on nanoscale conductors. Here, we carry out a thorough study of the current-induced forces and the electronic friction of systems whose electronic effective Hamiltonian can be described by an archetypal model, a single energy level coupled to two reservoirs. Our results can help better understand the general conditions that maximize the performance of different devices modeled as a quantum dot coupled to two electronic reservoirs. Additionally, they can be useful to rationalize the role of current-induced forces in the mechanical deformation of one-dimensional conductors.
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Affiliation(s)
- Sebastián E Deghi
- Instituto de Física Enrique Gaviola and Facultad de Matemática, Astronomía, Física y Computación, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, 5000, Argentina
| | - Lucas J Fernández-Alcázar
- Wave Transport in Complex Systems Lab, Department of Physics, Wesleyan University, Middletown, CT-06459, United States of America
| | - Horacio M Pastawski
- Instituto de Física Enrique Gaviola and Facultad de Matemática, Astronomía, Física y Computación, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, 5000, Argentina
| | - Raúl A Bustos-Marún
- Instituto de Física Enrique Gaviola and Facultad de Matemática, Astronomía, Física y Computación, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, 5000, Argentina
- Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, 5000, Argentina
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