1
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Liou F, Tsai HZ, Goodwin ZAH, Yang Y, Aikawa AS, Angeles BRP, Pezzini S, Nguyen L, Trishin S, Cheng Z, Zhou S, Roberts PW, Xu X, Watanabe K, Taniguchi T, Bellani V, Wang F, Lischner J, Crommie MF. Gate-Switchable Molecular Diffusion on a Graphene Field-Effect Transistor. ACS NANO 2024; 18:24262-24268. [PMID: 39158860 DOI: 10.1021/acsnano.4c05808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
Controlling the surface diffusion of particles on 2D devices creates opportunities for advancing microscopic processes such as nanoassembly, thin-film growth, and catalysis. Here, we demonstrate the ability to control the diffusion of F4TCNQ molecules at the surface of clean graphene field-effect transistors (FETs) via electrostatic gating. Tuning the back-gate voltage (VG) of a graphene FET switches molecular adsorbates between negative and neutral charge states, leading to dramatic changes in their diffusion properties. Scanning tunneling microscopy measurements reveal that the diffusivity of neutral molecules decreases rapidly with a decreasing VG and involves rotational diffusion processes. The molecular diffusivity of negatively charged molecules, on the other hand, remains nearly constant over a wide range of applied VG values and is dominated by purely translational processes. First-principles density functional theory calculations confirm that the energy landscapes experienced by neutral vs charged molecules lead to diffusion behavior consistent with experiment. Gate-tunability of the diffusion barrier for F4TCNQ molecules on graphene enables graphene FETs to act as diffusion switches.
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Affiliation(s)
- Franklin Liou
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at the University of California at Berkeley, Berkeley, California 94720, United States
| | - Hsin-Zon Tsai
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Zachary A H Goodwin
- Department of Materials, Imperial College London, Prince Consort Rd, London SW7 2BB, U.K
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Yiming Yang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Andrew S Aikawa
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Brian R P Angeles
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Sergio Pezzini
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa 56127, Italy
| | - Luc Nguyen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Sergey Trishin
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Zhichao Cheng
- Tsinghua-Berkeley Shenzhen Institute & Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Shizhe Zhou
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Paul W Roberts
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Xiaomin Xu
- Tsinghua-Berkeley Shenzhen Institute & Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | | | - Feng Wang
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at the University of California at Berkeley, Berkeley, California 94720, United States
| | - Johannes Lischner
- Department of Materials, Imperial College London, Prince Consort Rd, London SW7 2BB, U.K
| | - Michael F Crommie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoSciences Institute at the University of California at Berkeley, Berkeley, California 94720, United States
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2
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Drechsel C, D’Astolfo P, Liu JC, Glatzel T, Pawlak R, Meyer E. Topographic signatures and manipulations of Fe atoms, CO molecules and NaCl islands on superconducting Pb(111). BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2022; 13:1-9. [PMID: 35059274 PMCID: PMC8744454 DOI: 10.3762/bjnano.13.1] [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: 08/20/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
Topological superconductivity emerging in one- or two-dimensional hybrid materials is predicted as a key ingredient for quantum computing. However, not only the design of complex heterostructures is primordial for future applications but also the characterization of their electronic and structural properties at the atomic scale using the most advanced scanning probe microscopy techniques with functionalized tips. We report on the topographic signatures observed by scanning tunneling microscopy (STM) of carbon monoxide (CO) molecules, iron (Fe) atoms and sodium chloride (NaCl) islands deposited on superconducting Pb(111). For the CO adsorption a comparison with the Pb(110) substrate is demonstrated. We show a general propensity of these adsorbates to diffuse at low temperature under gentle scanning conditions. Our findings provide new insights into high-resolution probe microscopy imaging with terminated tips, decoupling atoms and molecules by NaCl islands or tip-induced lateral manipulation of iron atoms on top of the prototypical Pb(111) superconducting surface.
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Affiliation(s)
- Carl Drechsel
- Department of Physics, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Philipp D’Astolfo
- Department of Physics, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Jung-Ching Liu
- Department of Physics, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- Department of Physics, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Rémy Pawlak
- Department of Physics, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Ernst Meyer
- Department of Physics, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
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3
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Preis T, Vrbica S, Eroms J, Repp J, van Ruitenbeek JM. Current-Induced One-Dimensional Diffusion of Co Adatoms on Graphene Nanoribbons. NANO LETTERS 2021; 21:8794-8799. [PMID: 34652923 PMCID: PMC8554795 DOI: 10.1021/acs.nanolett.1c03073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/24/2021] [Indexed: 06/13/2023]
Abstract
One-dimensional diffusion of Co adatoms on graphene nanoribbons has been induced and investigated by means of scanning tunnelling microscopy (STM). To this end, the nanoribbons and the Co adatoms have been imaged before and after injecting current pulses into the nanoribbons, with the STM tip in direct contact with the ribbon. We observe current-induced motion of the Co atoms along the nanoribbons, which is approximately described by a distribution expected for a thermally activated one-dimensional random walk. This indicates that the nanoribbons reach temperatures far beyond 100 K, which is well above the temperature of the underlying Au substrate. This model system can be developed further for the study of electromigration at the single-atom level.
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Affiliation(s)
- Tobias Preis
- Institute
of Experimental and Applied Physics, University
of Regensburg, 93040 Regensburg, Germany
| | - Sasha Vrbica
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University, 2333 CA Leiden, The Netherlands
| | - Jonathan Eroms
- Institute
of Experimental and Applied Physics, University
of Regensburg, 93040 Regensburg, Germany
| | - Jascha Repp
- Institute
of Experimental and Applied Physics, University
of Regensburg, 93040 Regensburg, Germany
| | - Jan M. van Ruitenbeek
- Huygens-Kamerlingh
Onnes Laboratory, Leiden University, 2333 CA Leiden, The Netherlands
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4
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Peng Z, Di B, Li W, Liu D, Wen X, Zhu H, Song H, Zhang Y, Yin C, Zhou X, Wu K. Reversibly Switching the Charge State and Adsorption Location of A Single Potassium Atom on Ultrathin CuO Films. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Zhantao Peng
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Bin Di
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Wentao Li
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Dan Liu
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Xiaojie Wen
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Hao Zhu
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Huanjun Song
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Yajie Zhang
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Cen Yin
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Xiong Zhou
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Kai Wu
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
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5
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Peng Z, Di B, Li W, Liu D, Wen X, Zhu H, Song H, Zhang Y, Yin C, Zhou X, Wu K. Reversibly Switching the Charge State and Adsorption Location of A Single Potassium Atom on Ultrathin CuO Films. Angew Chem Int Ed Engl 2020; 59:14321-14325. [DOI: 10.1002/anie.202005370] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/13/2020] [Indexed: 11/07/2022]
Affiliation(s)
- Zhantao Peng
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Bin Di
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Wentao Li
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Dan Liu
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Xiaojie Wen
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Hao Zhu
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Huanjun Song
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Yajie Zhang
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Cen Yin
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Xiong Zhou
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
| | - Kai Wu
- BNLMS College of Chemistry and Molecular Engineering Peking University Beijing 100871 China
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6
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Scheuerer P, Patera LL, Simbürger F, Queck F, Swart I, Schuler B, Gross L, Moll N, Repp J. Charge-Induced Structural Changes in a Single Molecule Investigated by Atomic Force Microscopy. PHYSICAL REVIEW LETTERS 2019; 123:066001. [PMID: 31491133 DOI: 10.1103/physrevlett.123.066001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/12/2019] [Indexed: 06/10/2023]
Abstract
Intramolecular structural relaxations occurring upon electron transfer are crucial in determining the rate of redox reactions. Here, we demonstrate that subangstrom structural changes occurring upon single-electron charging can be quantified by means of atomically resolved atomic force microscopy (AFM) for the case of single copper(II)phthalocyanine (CuPc) molecules deposited on an ultrathin NaCl film. Imaging the molecule in distinct charge states (neutral and anionic) reveals characteristic differences in the AFM contrast. In comparison to density functional theory simulations these changes in contrast can be directly related to relaxations of the molecule's geometric structure upon charging. The dominant contribution arises from a nonhomogeneous vertical relaxation of the molecule, caused by a change in the electrostatic interaction with the surface.
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Affiliation(s)
- Philipp Scheuerer
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Laerte L Patera
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Felix Simbürger
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Fabian Queck
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Ingmar Swart
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
- Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80 000, 3508 TA Utrecht, Netherlands
| | - Bruno Schuler
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Leo Gross
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
| | - Nikolaj Moll
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
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7
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Fatayer S, Moll N, Collazos S, Pérez D, Guitián E, Peña D, Gross L, Meyer G. Controlled Fragmentation of Single Molecules with Atomic Force Microscopy by Employing Doubly Charged States. PHYSICAL REVIEW LETTERS 2018; 121:226101. [PMID: 30547655 DOI: 10.1103/physrevlett.121.226101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Indexed: 06/09/2023]
Abstract
By atom manipulation we performed on-surface chemical reactions of a single molecule on a multilayer insulating film using noncontact atomic force microscopy. The single-electron sensitivity of atomic force microscopy allows us to follow the addition of single electrons to the molecule and the investigation of the reaction products. By performing a novel strategy based on long-lived doubly charged states a single molecule is fragmented. The fragmentation can be reverted by again changing the charge state of the system, characterizing a reversible reaction. The experimental results in addition to density-functional theory provide insight into the charge states of the different products and reaction pathways. Similar molecular systems could be used as charge-transfer units and to induce reversible chemical reactions.
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Affiliation(s)
- Shadi Fatayer
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Nikolaj Moll
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Sara Collazos
- Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Dolores Pérez
- Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Enrique Guitián
- Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Diego Peña
- Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Leo Gross
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Gerhard Meyer
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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8
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Fatayer S, Schuler B, Steurer W, Scivetti I, Repp J, Gross L, Persson M, Meyer G. Reorganization energy upon charging a single molecule on an insulator measured by atomic force microscopy. NATURE NANOTECHNOLOGY 2018; 13:376-380. [PMID: 29662243 DOI: 10.1038/s41565-018-0087-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 02/05/2018] [Indexed: 05/28/2023]
Abstract
Intermolecular single-electron transfer on electrically insulating films is a key process in molecular electronics1-4 and an important example of a redox reaction5,6. Electron-transfer rates in molecular systems depend on a few fundamental parameters, such as interadsorbate distance, temperature and, in particular, the Marcus reorganization energy 7 . This crucial parameter is the energy gain that results from the distortion of the equilibrium nuclear geometry in the molecule and its environment on charging8,9. The substrate, especially ionic films 10 , can have an important influence on the reorganization energy11,12. Reorganization energies are measured in electrochemistry 13 as well as with optical14,15 and photoemission spectroscopies16,17, but not at the single-molecule limit and nor on insulating surfaces. Atomic force microscopy (AFM), with single-charge sensitivity18-22, atomic-scale spatial resolution 20 and operable on insulating films, overcomes these challenges. Here, we investigate redox reactions of single naphthalocyanine (NPc) molecules on multilayered NaCl films. Employing the atomic force microscope as an ultralow current meter allows us to measure the differential conductance related to transitions between two charge states in both directions. Thereby, the reorganization energy of NPc on NaCl is determined as (0.8 ± 0.2) eV, and density functional theory (DFT) calculations provide the atomistic picture of the nuclear relaxations on charging. Our approach presents a route to perform tunnelling spectroscopy of single adsorbates on insulating substrates and provides insight into single-electron intermolecular transport.
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Affiliation(s)
| | - Bruno Schuler
- IBM Research - Zurich, Rüschlikon, Switzerland
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Ivan Scivetti
- Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool, UK
- Daresbury Laboratory, Sc. Tech., Warrington, UK
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - Leo Gross
- IBM Research - Zurich, Rüschlikon, Switzerland
| | - Mats Persson
- Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool, UK
- Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden
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9
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Schneider WD, Heyde M, Freund HJ. Charge Control in Model Catalysis: The Decisive Role of the Oxide-Nanoparticle Interface. Chemistry 2017; 24:2317-2327. [PMID: 28857287 DOI: 10.1002/chem.201703169] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Indexed: 11/06/2022]
Abstract
In chemistry and physics the electronic charge on a species or material is one important determinant of its properties. In the present Minireview, the essential requirements for a model catalyst system suitable to study charge control are discussed. The ideal model catalyst for this purpose consists of a material system, which comprises a single crystal metal support, covered by an epitaxially grown ultrathin oxide film, and flat, two-dimensional nanoparticles residing on this film. Several examples from the literature are selected and presented, which illustrate various aspects of electron transport from the support to the nanoparticle and vice versa. Key experiments demonstrate charge control within such model catalysts and give direct evidence for a chemical reaction at the perimeter of Au nanoparticles. The concepts derived from these studies are then taken a step further to see how they may be applied for bulk powder oxide supported nanoparticles as they are frequently found in catalytically active materials.
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Affiliation(s)
- Wolf-Dieter Schneider
- Department of Chemical Physics, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
| | - Markus Heyde
- Department of Chemical Physics, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
| | - Hans-Joachim Freund
- Department of Chemical Physics, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
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10
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Pawlak R, Meier T, Renaud N, Kisiel M, Hinaut A, Glatzel T, Sordes D, Durand C, Soe WH, Baratoff A, Joachim C, Housecroft CE, Constable EC, Meyer E. Design and Characterization of an Electrically Powered Single Molecule on Gold. ACS NANO 2017; 11:9930-9940. [PMID: 28756663 DOI: 10.1021/acsnano.7b03955] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The surface diffusion of individual molecules is of paramount importance in self-assembly processes and catalytic processes. However, the fundamental understanding of molecule diffusion peculiarities considering conformations and adsorption sites remain poorly known at the atomic scale. Here, we probe the 4'-(4-tolyl)-2,2':6',2″-terpyridine adsorbed on the Au(111) herringbone structure combining scanning tunneling microscopy and atomic force microscopy. Molecules are controllably translated by electrons excitations over the reconstruction, except at elbows acting as pinning centers. Experimental data supported by theoretical calculations show the formation of coordination bonds between the molecule and Au atoms of the surface. Using force spectroscopy, we quantify local variation of the surface potential and the lateral force required to move the molecule. We found an elevation of the diffusion barrier at elbows of the reconstruction of ∼100 meV compared to the rest of the surface.
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Affiliation(s)
- Rémy Pawlak
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Tobias Meier
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Nicolas Renaud
- Delft University of Technology , Department of Chemical Engineering, van de Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Marcin Kisiel
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Delphine Sordes
- CEMES-CNRS , NanoSciences Group & MANA Satellite, 29 rue Jeanne Marvig, BP 94347, Toulouse F-31055 Cedex 4, France
| | - Corentin Durand
- CEMES-CNRS , NanoSciences Group & MANA Satellite, 29 rue Jeanne Marvig, BP 94347, Toulouse F-31055 Cedex 4, France
| | - We-Hyo Soe
- CEMES-CNRS , NanoSciences Group & MANA Satellite, 29 rue Jeanne Marvig, BP 94347, Toulouse F-31055 Cedex 4, France
| | - Alexis Baratoff
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Christian Joachim
- CEMES-CNRS , NanoSciences Group & MANA Satellite, 29 rue Jeanne Marvig, BP 94347, Toulouse F-31055 Cedex 4, France
| | - Catherine E Housecroft
- Department of Chemistry, University of Basel , Spitalstrasse 51, 4056 Basel, Switzerland
| | - Edwin C Constable
- Department of Chemistry, University of Basel , Spitalstrasse 51, 4056 Basel, Switzerland
| | - Ernst Meyer
- Department of Physics, University of Basel , Klingelbergstrasse 82, 4056 Basel, Switzerland
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11
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Cheynis F, Curiotto S, Leroy F, Müller P. Spatial inhomogeneity and temporal dynamics of a 2D electron gas in interaction with a 2D adatom gas. Sci Rep 2017; 7:10642. [PMID: 28878360 PMCID: PMC5587567 DOI: 10.1038/s41598-017-10300-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/07/2017] [Indexed: 11/09/2022] Open
Abstract
Fundamental interest for 2D electron gas (2DEG) systems has been recently renewed with the advent of 2D materials and their potential high-impact applications in optoelectronics. Here, we investigate a 2DEG created by the electron transfer from a Ag adatom gas deposited on a Si(111) \documentclass[12pt]{minimal}
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\begin{document}$$\sqrt{{\bf{3}}}{\boldsymbol{\times }}\sqrt{{\bf{3}}}$$\end{document}3×3-Ag surface to an electronic surface state. Using low-energy electron microscopy (LEEM), we measure the Ag adatom gas concentration and the 2DEG-induced charge transfer. We demonstrate a linear dependence of the surface work function change on the Ag adatom gas concentration. A breakdown of the linear relationship is induced by the occurrence of the Ag adatom gas superstructure identified as Si(111) \documentclass[12pt]{minimal}
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\begin{document}$$\sqrt{{\bf{21}}}{\boldsymbol{\times }}\sqrt{{\bf{21}}}$$\end{document}21×21-Ag only observed below room temperature. We evidence below room temperature a confinement of the 2DEG on atomic terraces characterised by spatial inhomogeneities of the 2DEG-induced charge transfer along with temporal fluctuations. These variations mirror the Ag adatom gas concentration changes induced by the growth of 3D Ag islands and the occurrence of an Ehrlich-Schwoebel diffusion barrier of 155 ± 10 meV.
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Affiliation(s)
- F Cheynis
- Aix Marseille Univ, CNRS, CINAM, Marseille, France.
| | - S Curiotto
- Aix Marseille Univ, CNRS, CINAM, Marseille, France
| | - F Leroy
- Aix Marseille Univ, CNRS, CINAM, Marseille, France
| | - P Müller
- Aix Marseille Univ, CNRS, CINAM, Marseille, France
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12
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Setvin M, Hulva J, Parkinson GS, Schmid M, Diebold U. Electron transfer between anatase TiO 2 and an O 2 molecule directly observed by atomic force microscopy. Proc Natl Acad Sci U S A 2017; 114:E2556-E2562. [PMID: 28289217 PMCID: PMC5380104 DOI: 10.1073/pnas.1618723114] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activation of molecular oxygen is a key step in converting fuels into energy, but there is precious little experimental insight into how the process proceeds at the atomic scale. Here, we show that a combined atomic force microscopy/scanning tunneling microscopy (AFM/STM) experiment can both distinguish neutral O2 molecules in the triplet state from negatively charged (O2)- radicals and charge and discharge the molecules at will. By measuring the chemical forces above the different species adsorbed on an anatase TiO2 surface, we show that the tip-generated (O2)- radicals are identical to those created when (i) an O2 molecule accepts an electron from a near-surface dopant or (ii) when a photo-generated electron is transferred following irradiation of the anatase sample with UV light. Kelvin probe spectroscopy measurements indicate that electron transfer between the TiO2 and the adsorbed molecules is governed by competition between electron affinity of the physisorbed (triplet) O2 and band bending induced by the (O2)- radicals. Temperature-programmed desorption and X-ray photoelectron spectroscopy data provide information about thermal stability of the species, and confirm the chemical identification inferred from AFM/STM.
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Affiliation(s)
- Martin Setvin
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Jan Hulva
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | - Michael Schmid
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
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