1
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Bi L, Jamnuch S, Chen A, Do A, Balto KP, Wang Z, Zhu Q, Wang Y, Zhang Y, Tao AR, Pascal TA, Figueroa JS, Li S. Molecular-Scale Visualization of Steric Effects of Ligand Binding to Reconstructed Au(111) Surfaces. J Am Chem Soc 2024; 146:11764-11772. [PMID: 38625675 PMCID: PMC11066864 DOI: 10.1021/jacs.4c00002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/17/2024]
Abstract
Direct imaging of single molecules at nanostructured interfaces is a grand challenge with potential to enable new, precise material architectures and technologies. Of particular interest are the structural morphology and spectroscopic signatures of the adsorbed molecule, where modern probes are only now being developed with the necessary spatial and energetic resolution to provide detailed information at the molecule-surface interface. Here, we directly characterize the adsorption of individual m-terphenyl isocyanide ligands on a reconstructed Au(111) surface through scanning tunneling microscopy and inelastic electron tunneling spectroscopy. The site-dependent steric pressure of the various surface features alters the vibrational fingerprints of the m-terphenyl isocyanides, which are characterized with single-molecule precision through joint experimental and theoretical approaches. This study provides molecular-level insights into the steric-pressure-enabled surface binding selectivity as well as its effect on the chemical properties of individual surface-binding ligands.
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Affiliation(s)
- Liya Bi
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92093-0309, United States
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
| | - Sasawat Jamnuch
- Department
of Nano and Chemical Engineering, University
of California, San Diego, California 92093-0448, United States
| | - Amanda Chen
- Department
of Nano and Chemical Engineering, University
of California, San Diego, California 92093-0448, United States
| | - Alexandria Do
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
- Department
of Nano and Chemical Engineering, University
of California, San Diego, California 92093-0448, United States
| | - Krista P. Balto
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92093-0309, United States
| | - Zhe Wang
- Institute
of Fundamental and Frontier Sciences, University
of Electronic Science and Technology of China, Chengdu 611731, China
| | - Qingyi Zhu
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92093-0309, United States
| | - Yufei Wang
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
- Department
of Nano and Chemical Engineering, University
of California, San Diego, California 92093-0448, United States
| | - Yanning Zhang
- Institute
of Fundamental and Frontier Sciences, University
of Electronic Science and Technology of China, Chengdu 611731, China
| | - Andrea R. Tao
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92093-0309, United States
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
- Department
of Nano and Chemical Engineering, University
of California, San Diego, California 92093-0448, United States
| | - Tod A. Pascal
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
- Department
of Nano and Chemical Engineering, University
of California, San Diego, California 92093-0448, United States
| | - Joshua S. Figueroa
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92093-0309, United States
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
| | - Shaowei Li
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92093-0309, United States
- Program
in Materials Science and Engineering, University
of California, San Diego, California 92093-0418, United States
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2
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Xia Y, Wang L, Ho W. Mechanisms Underlying a Quantum Superposition Microscope Based on THz-Driven Coherent Oscillations in a Two-Level Molecular Sensor. PHYSICAL REVIEW LETTERS 2024; 132:076903. [PMID: 38427859 DOI: 10.1103/physrevlett.132.076903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 12/07/2023] [Accepted: 01/04/2024] [Indexed: 03/03/2024]
Abstract
We report pump-probe measurements of a hydrogen molecule (H_{2}) in the tunnel junction of a scanning tunneling microscope coupled to ultrashort terahertz (THz) pulses. The coherent oscillation of the THz-induced dc tunneling current at a frequency of ∼0.5 THz fingerprints the absorption by H_{2} as a two-level system (TLS). Two components of the oscillatory signal are observed and point to both photon and field aspects of the THz pulses. A few loosely bound states with similar energies for the upper state of the TLS are evidenced by the coherent revival of oscillatory signal. Furthermore, the comparison of spectroscopic features of H_{2} with different tips provides an understanding of the TLS for H_{2}.
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Affiliation(s)
- Yunpeng Xia
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Likun Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - W Ho
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA
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3
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Wang L, Bai D, Xia Y, Ho W. Electrical Manipulation of Quantum Coherence in a Two-Level Molecular System. PHYSICAL REVIEW LETTERS 2023; 130:096201. [PMID: 36930940 DOI: 10.1103/physrevlett.130.096201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/06/2023] [Indexed: 06/18/2023]
Abstract
We report the manipulation of ultrafast quantum coherence of a two-level single hydrogen molecular system by employing static electric field from the sample bias in a femtosecond terahertz scanning tunneling microscope. A H_{2} molecule adsorbed on the polar Cu_{2}N surface develops an electric dipole and exhibits a giant Stark effect. An avoided crossing of the quantum state energy levels is derived from the resonant frequency of the single H_{2} two levels in a double-well potential. The dephasing time of the initial wave packet can also be changed by applying the electric field. The electrical manipulation for different tunneling gaps in three dimensions allows quantification of the surface electrostatic fields at the atomic scale. Our work demonstrated the potential application of molecules as controllable two-level molecular systems.
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Affiliation(s)
- Likun Wang
- Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA
| | - Dan Bai
- Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA
| | - Yunpeng Xia
- Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA
| | - W Ho
- Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, USA
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4
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Xiao J, Zhao W, Li L, Ma L, Tian G. Adsorption properties of a paracyclophane molecule on NaCl/Au surfaces: a first-principles study. Phys Chem Chem Phys 2023; 25:6060-6066. [PMID: 36751852 DOI: 10.1039/d2cp04745d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ultrathin insulating layers are commonly applied in scanning tunneling microscope (STM) measurements on molecular systems to preserve the intrinsic properties of a sample. We examine in the present work the adsorption properties of a double-decker 3,3-paracyclophane (PCP) molecule supported on Au surfaces with thin NaCl monolayers (MLs) as the decoupling spacer by using first-principles calculations. The interactions between the adsorbed molecule and the substrate were analyzed in terms of the adsorption energy, dispersion interactions, charge transfer, and molecular structure changes. The simulation results show that the presence of NaCl can significantly reduce the adsorption energy as well as the charge transfer between the molecule and the substrate. Detailed analysis of the differential charge density and partial charge density of states indicates that three MLs of NaCl are sufficient to decouple the molecule from the Au substrate with no significant changes in the adsorption properties of the PCP with the further increase of the thickness of the NaCl spacer. These results could be helpful for the application of the interesting double-decker molecules as functional single-molecule devices where the intrinsic molecular properties need to be preserved.
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Affiliation(s)
- Jiyin Xiao
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Wenjing Zhao
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Li Li
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Liang Ma
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
| | - Guangjun Tian
- State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao, 066004, P. R. China.
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5
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Wang L, Xia Y, Ho W. Atomic-scale quantum sensing based on the ultrafast coherence of an H 2 molecule in an STM cavity. Science 2022; 376:401-405. [PMID: 35446636 DOI: 10.1126/science.abn9220] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A scanning tunneling microscope (STM) combined with a pump-probe femtosecond terahertz (THz) laser can enable coherence measurements of single molecules. We report THz pump-probe measurements that demonstrate quantum sensing based on a hydrogen (H2) molecule in the cavity created with an STM tip near a surface. Atomic-scale spatial and femtosecond temporal resolutions were obtained from this quantum coherence. The H2 acts as a two-level system, with its coherent superposition exhibiting extreme sensitivity to the applied electric field and the underlying atomic composition of the copper nitride (Cu2N) monolayer islands grown on a Cu(100) surface. We acquired time-resolved images of THz rectification of H2 over Cu2N islands for variable pump-probe delay times to visualize the heterogeneity of the chemical environment at sub-angstrom scale.
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Affiliation(s)
- Likun Wang
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Yunpeng Xia
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - W Ho
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA.,Department of Chemistry, University of California, Irvine, CA 92697, USA
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6
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Abstract
Hydrogen molecules exist in the form of two distinct isomers that can be interconverted by physical catalysis. These ortho and para forms have different thermodynamical properties. Over the last century, the catalysts developed to convert hydrogen from one form to another, in laboratories and industries, were magnetic and the interpretations relied on magnetic dipolar interactions. The variety concentration of a sample and the conversion rates induced by a catalytic action were mostly measured by thermal methods related to the diffusion of the o-p reaction heat. At the turning of the new century, the nature of the studied catalysts and the type of measures and motivations completely changed. Catalysts investigated now are non-magnetic and new spectroscopic measurements have been developed. After a fast survey of the past studies, the review details the spectroscopic methods, emphasizing their originalities, performances and refinements: how Infra-Red measurements characterize the catalytic sites and follow the conversion in real-time, Ultra-Violet irradiations explore the electronic nature of the reaction and hyper-frequencies driving the nuclear spins. The new catalysts, metallic or insulating, are detailed to display the operating electronic structure. New electromagnetic mechanisms, involving energy and momenta transfers, are discovered providing a classification frame for the newly observed reactions.
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7
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Merino P, Rosławska A, Grewal A, Leon CC, Gonzalez C, Kuhnke K, Kern K. Gold Chain Formation via Local Lifting of Surface Reconstruction by Hot Electron Injection on H 2(D 2)/Au(111). ACS NANO 2020; 14:15241-15247. [PMID: 33119271 PMCID: PMC7610521 DOI: 10.1021/acsnano.0c05507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The hexagonal close packed surface of gold shows a 22 × 3 "herringbone" surface reconstruction which makes it unique among the (111) surfaces of all metals. This long-range energetically favored dislocation pattern appears in response to the strong tensile stress that would be present on the unreconstructed surface. Adsorption of molecular and atomic species can be used to tune this surface stress and lift the herringbone reconstruction. Here we show that herringbone reconstruction can be controllably lifted in ultrahigh vacuum at cryogenic temperatures by precise hot electron injection in the presence of hydrogen molecules. We use the sharp tip of a scanning tunneling microscope (STM) for charge carrier injection and characterization of the resulting chain nanostructures. By comparing STM images, rotational spectromicroscopy and ab initio calculations, we show that formation of gold atomic chains is associated with release of gold atoms from the surface, lifting of the reconstruction, dissociation of H2 molecules, and formation of surface hydrides. Gold hydrides grow in a zipper-like mechanism forming chains along the [11̅0] directions of the Au(111) surface and can be manipulated by further electron injection. Finally, we demonstrate that Au(111) terraces can be transformed with nearly perfect terrace selectivity over distances of hundreds of nanometers.
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Affiliation(s)
- P. Merino
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D70569, Stuttgart, Germany
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, E28049, Madrid, Spain
- Instituto de Física Fundamental, CSIC, Serrano 121, E28006, Madrid, Spain
| | - A. Rosławska
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D70569, Stuttgart, Germany
| | - A. Grewal
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D70569, Stuttgart, Germany
| | - C. C. Leon
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D70569, Stuttgart, Germany
| | - C. Gonzalez
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias, Universidad Autónoma de Madrid, E28049 Madrid, Spain
- Departamento de Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Instituto de Magnetismo Aplicado UCM-ADIF, Vía de Servicio A-6, 900, E-28232 Las Rozas de Madrid, Spain
| | - K. Kuhnke
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D70569, Stuttgart, Germany
| | - K. Kern
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D70569, Stuttgart, Germany
- Institut de Physique, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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8
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Guo J, Cao D, Chen J, Bian K, Xu LM, Wang EG, Jiang Y. Probing the intermolecular coupled vibrations in a water cluster with inelastic electron tunneling spectroscopy. J Chem Phys 2020; 152:234301. [PMID: 32571057 DOI: 10.1063/5.0009385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The hydrogen-bonding networks of water have strong intra- and intermolecular vibrational coupling which influences the energy dissipation and proton transfer in water. Disentangling and quantitative characterization of different coupling effects in water at a single-molecular level still remains a great challenge. Using tip-enhanced inelastic electron tunneling spectroscopy (IETS) based on low-temperature scanning tunneling microscopy, we report the direct quantitative assessment of the intermolecular coupling constants of the OH-stretch vibrational bands of an isolated water tetramer adsorbed on a Au(111)-supported NaCl(001) bilayer film. This is achieved by distinguishing various coupled modes of the H-bonded O-H stretching vibrations through tip-height dependent IET spectra. In contrast, such vibrational coupling is negligible in the half-deuterated water tetramer owing to the large energy mismatch between the OH and OD stretching modes. Not only do these findings advance our understanding on the effects of local environment on the intermolecular vibrational coupling in water, but also open up a new route for vibrational spectroscopic studies of extended H-bonded network at the single-molecular level.
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Affiliation(s)
- Jing Guo
- College of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Duanyun Cao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Ji Chen
- School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Ke Bian
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Li-Mei Xu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - En-Ge Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Ying Jiang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
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9
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Li S, Zhong C, Henning A, Sangwan VK, Zhou Q, Liu X, Rahn MS, Wells SA, Park HY, Luxa J, Sofer Z, Facchetti A, Darancet P, Marks TJ, Lauhon LJ, Weiss EA, Hersam MC. Molecular-Scale Characterization of Photoinduced Charge Separation in Mixed-Dimensional InSe-Organic van der Waals Heterostructures. ACS NANO 2020; 14:3509-3518. [PMID: 32078300 DOI: 10.1021/acsnano.9b09661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Layered indium selenide (InSe) is an emerging two-dimensional semiconductor that has shown significant promise for high-performance transistors and photodetectors. The range of optoelectronic applications for InSe can potentially be broadened by forming mixed-dimensional van der Waals heterostructures with zero-dimensional molecular systems that are widely employed in organic electronics and photovoltaics. Here, we report the spatially resolved investigation of photoinduced charge separation between InSe and two molecules (C70 and C8-BTBT) using scanning tunneling microscopy combined with laser illumination. We experimentally and computationally show that InSe forms type-II and type-I heterojunctions with C70 and C8-BTBT, respectively, due to an interplay of charge transfer and dielectric screening at the interface. Laser-excited scanning tunneling spectroscopy reveals a ∼0.25 eV decrease in the energy of the lowest unoccupied molecular orbital of C70 with optical illumination. Furthermore, photoluminescence spectroscopy and Kelvin probe force microscopy indicate that electron transfer from InSe to C70 in the type-II heterojunction induces a photovoltage that quantitatively matches the observed downshift in the tunneling spectra. In contrast, no significant changes are observed upon optical illumination in the type-I heterojunction formed between InSe and C8-BTBT. Density functional theory calculations further show that, despite the weak coupling between the molecular species and InSe, the band alignment of these mixed-dimensional heterostructures strongly differs from the one suggested by the ionization potential and electronic affinities of the isolated components. Self-energy-corrected density functional theory indicates that these effects are the result of the combination of charge redistribution at the interface and heterogeneous dielectric screening of the electron-electron interactions in the heterostructure. In addition to providing specific insight for mixed-dimensional InSe-organic van der Waals heterostructures, this work establishes a general experimental methodology for studying localized charge transfer at the molecular scale that is applicable to other photoactive nanoscale systems.
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Affiliation(s)
- Shaowei Li
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Chengmei Zhong
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Alex Henning
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Qunfei Zhou
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Northwestern Argonne Institute for Science and Engineering, Evanston, Illinois 60208, United States
| | - Xiaolong Liu
- Applied Physics Graduate Program, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Matthew S Rahn
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Spencer A Wells
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Hong Youl Park
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Jan Luxa
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Zdeněk Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic
| | - Antonio Facchetti
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Pierre Darancet
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Northwestern Argonne Institute for Science and Engineering, Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
- Applied Physics Graduate Program, Northwestern University, Evanston, Illinois 60208-3113, United States
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10
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Cohen G, Galperin M. Green’s function methods for single molecule junctions. J Chem Phys 2020; 152:090901. [DOI: 10.1063/1.5145210] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Guy Cohen
- The Raymond and Beverley Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
- School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
| | - Michael Galperin
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
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11
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Li S, Czap G, Wang H, Wang L, Chen S, Yu A, Wu R, Ho W. Bond-Selected Photodissociation of Single Molecules Adsorbed on Metal Surfaces. PHYSICAL REVIEW LETTERS 2019; 122:077401. [PMID: 30848644 DOI: 10.1103/physrevlett.122.077401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 12/02/2018] [Indexed: 06/09/2023]
Abstract
We report the photoassisted activation of selected C─H bonds in individual molecules adsorbed on metal surfaces within the junction of a scanning tunneling microscope. Photons can couple to the C─H bond activation of specific hydrocarbons through a resonant photoassisted tunneling process. The molecule to be activated can be selected by positioning the tip with subangstrom resolution. Furthermore, structural tomography of the molecule and its dissociation products are imaged at different heights by the inelastic tunneling probe. The demonstration of single bond dissociation induced by resonant photoassisted tunneling electrons implies the attainment of atomic scale spatial resolution for bond-selected photochemistry.
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Affiliation(s)
- Shaowei Li
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Gregory Czap
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Hui Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Likun Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Siyu Chen
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Arthur Yu
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - W Ho
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA
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12
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Krane N, Lotze C, Reecht G, Zhang L, Briseno AL, Franke KJ. High-Resolution Vibronic Spectra of Molecules on Molybdenum Disulfide Allow for Rotamer Identification. ACS NANO 2018; 12:11698-11703. [PMID: 30380829 DOI: 10.1021/acsnano.8b07414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Tunneling spectroscopy is an important tool for the chemical identification of single molecules on surfaces. Here, we show that oligothiophene-based large organic molecules which only differ by single bond orientations can be distinguished by their vibronic fingerprint. These molecules were deposited on a monolayer of the transition metal dichalcogenide molybdenum disulfide (MoS2) on top of a Au(111) substrate. MoS2 features an electronic band gap for efficient decoupling of the molecular states. Furthermore, it exhibits a small electron-phonon coupling strength. Both of these material properties allow for the resolution of vibronic states in the range of the limit set by temperature broadening in our scanning tunneling microscope at 4.6 K. Using DFT calculations of the molecule in gas phase provides all details for an accurate simulation of the vibronic spectra of both rotamers.
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Affiliation(s)
- Nils Krane
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Christian Lotze
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Gaël Reecht
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Lei Zhang
- Department of Polymer Science and Engineering , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Alejandro L Briseno
- Department of Polymer Science and Engineering , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Katharina J Franke
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
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13
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Sarasola A, Abadía M, Rogero C, Garcia-Lekue A. Theoretical Insights into Unexpected Molecular Core Level Shifts: Chemical and Surface Effects. J Phys Chem Lett 2017; 8:5718-5724. [PMID: 29110481 DOI: 10.1021/acs.jpclett.7b02583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A set of density-functional theory based tools is employed to elucidate the influence of chemical and surface-induced changes on the core level shifts of X-ray photoelectron spectroscopy experiments. The capabilities of our tools are demonstrated by analyzing the origin of an unpredicted component in the N 1s core level spectra of metal phthalocyanine molecules (in particular ZnPc) adsorbed on Cu(110). We address surface induced effects, such as splitting of the lowest unoccupied molecular orbital or local electrostatic effects, demonstrating that these cannot account for the huge core level shift measured experimentally. Our calculations also show that, when adsorbed at low temperatures, these molecules might capture hydrogen atoms from the surface, giving rise to hydrogenated molecular species and, consequently, to an extra component in the molecular core level spectra. Only upon annealing, and subsequent hydrogen release, would the molecules recover their nominal structural and electronic properties.
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Affiliation(s)
- A Sarasola
- Departamento de Física Aplicada I, UPV/EHU , Plaza Europa 1, E-20018, San Sebastián, Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
| | - M Abadía
- Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - C Rogero
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
- Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
| | - A Garcia-Lekue
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, E-20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, E-48011, Bilbao, Spain
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14
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Han Z, Czap G, Xu C, Chiang CL, Yuan D, Wu R, Ho W. Probing Intermolecular Coupled Vibrations between Two Molecules. PHYSICAL REVIEW LETTERS 2017; 118:036801. [PMID: 28157347 DOI: 10.1103/physrevlett.118.036801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Indexed: 06/06/2023]
Abstract
Intermolecular interactions can induce energy shifts and coupling of molecular vibrations. However, the detection of intermolecular coupled vibrations has not been reported at the single molecule level. Here we detected an intermolecular coupled vibration between two CO molecules, one on the surface and another on the tip within the gap of a subkelvin scanning tunneling microscope, and analyzed the results by density functional calculations. We attribute the evolution of the energy and intensity of this coupled vibration as a function of tip-sample distance to the tilting and orbital alignment of the two CO molecules.
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Affiliation(s)
- Zhumin Han
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Gregory Czap
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Chen Xu
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Chi-Lun Chiang
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - Dingwang Yuan
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
- Center for High Resolution Electron Microscopy, College of Materials Science and Engineering, Hunan University, Changsha 410082, China
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
| | - W Ho
- Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
- Department of Chemistry, University of California, Irvine, California 92697-2025, USA
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15
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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16
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Jiang Z, Wang H, Sanvito S, Hou S. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface. J Chem Phys 2015; 143:234709. [PMID: 26696072 DOI: 10.1063/1.4938087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4pz atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.
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Affiliation(s)
- Zhuoling Jiang
- Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Hao Wang
- Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Shimin Hou
- Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
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17
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Wang H, Li S, He H, Yu A, Toledo F, Han Z, Ho W, Wu R. Trapping and Characterization of a Single Hydrogen Molecule in a Continuously Tunable Nanocavity. J Phys Chem Lett 2015; 6:3453-3457. [PMID: 26291093 DOI: 10.1021/acs.jpclett.5b01501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using inelastic electron tunneling spectroscopy with the scanning tunneling microscope (STM-IETS) and density functional theory calculations (DFT), we investigated properties of a single H2 molecule trapped in nanocavities with controlled shape and separation between the STM tip and the Au (110) surface. The STM tip not only serves for the purpose of characterization, but also is directly involved in modification of chemical environment of molecule. The bond length of H2 expands in the atop cavity, with a tendency of dissociation when the gap closes, whereas it remains unchanged in the trough cavity. The availability of two substantially different cavities in the same setup allows understanding of H2 adsorption on noble metal surfaces and sets a path for manipulating a single chemical bond by design.
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Affiliation(s)
- Hui Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
| | - Shaowei Li
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
| | - Haiyan He
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
- Department of Physics, University Science and Technology of China , Hefei, Anhui 230026, China
| | - Arthur Yu
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
| | - Freddy Toledo
- Department of Chemistry, University of California , Irvine, California 92697-2025, United States
| | - Zhumin Han
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
| | - W Ho
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
- Department of Chemistry, University of California , Irvine, California 92697-2025, United States
| | - Ruqian Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University , Shanghai 200433, China
- Department of Physics and Astronomy, University of California , Irvine, California 92697-4575, United States
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