1
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Wang Z, Yin R, Tang Z, Du H, Liang Y, Wang X, Deng QS, Tan YZ, Zhang Y, Ma C, Tan S, Wang B. Topologically Localized Vibronic Excitations in Second-Layer Graphene Nanoribbons. PHYSICAL REVIEW LETTERS 2024; 133:036401. [PMID: 39094172 DOI: 10.1103/physrevlett.133.036401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 06/06/2024] [Indexed: 08/04/2024]
Abstract
It is of fundamental importance to characterize the intrinsic properties, like the topological end states, in the on-surface synthesized graphene nanoribbons (GNRs), but the strong electronic interaction with the metal substrate usually smears out their characteristic features. Here, we report our approach to investigate the vibronic excitations of the topological end states in self-decoupled second-layer GNRs, which are grown using an on-surface squeezing-induced spillover strategy. The vibronic progressions show highly spatially localized distributions at the second-layer GNR ends, which can be ascribed to the decoupling-extended lifetime of charging through resonant electron tunneling at the topological end states. In combination with theoretical calculations, we assign the vibronic progressions to specific vibrational modes that mediate the vibronic excitations. The spatial distribution of each resolved excitation shows evident characteristics beyond the conventional Franck-Condon picture. Our work by direct growth of second-layer GNRs provides an effective way to explore the interplay between the intrinsic electronic, vibrational, and topological properties.
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Affiliation(s)
| | | | | | | | | | | | - Qing-Song Deng
- Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, China
| | - Yuan-Zhi Tan
- Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, 361005 Xiamen, China
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2
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Han H, Park Y, Kim Y, Ding F, Shin HJ. Controlled dissolution of a single ion from a salt interface. Nat Commun 2024; 15:2401. [PMID: 38493203 PMCID: PMC10944500 DOI: 10.1038/s41467-024-46704-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 03/07/2024] [Indexed: 03/18/2024] Open
Abstract
Interactions between monatomic ions and water molecules are fundamental to understanding the hydration of complex polyatomic ions and ionic process. Among the simplest and well-established ion-related reactions is dissolution of salt in water, which is an endothermic process requiring an increase in entropy. Extensive efforts have been made to date; however, most studies at single-ion level have been limited to theoretical approaches. Here, we demonstrate the salt dissolution process by manipulating a single water molecule at an under-coordinated site of a sodium chloride film. Manipulation of molecule in a controlled manner enables us to understand ion-water interaction as well as dynamics of water molecules at NaCl interfaces, which are responsible for the selective dissolution of anions. The water dipole polarizes the anion in the NaCl ionic crystal, resulting in strong anion-water interaction and weakening of the ionic bonds. Our results provide insights into a simple but important elementary step of the single-ion chemistry, which may be useful in ion-related sciences and technologies.
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Affiliation(s)
- Huijun Han
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Yunjae Park
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea
| | - Yohan Kim
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Feng Ding
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
- Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen, 518055, China.
| | - Hyung-Joon Shin
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea.
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3
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Duan J, Wang J, Hou L, Ji P, Zhang W, Liu J, Zhu X, Sun Z, Ma Y, Ma L. Application of Scanning Tunneling Microscopy and Spectroscopy in the Studies of Colloidal Quantum Qots. CHEM REC 2023; 23:e202300120. [PMID: 37255365 DOI: 10.1002/tcr.202300120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/15/2023] [Indexed: 06/01/2023]
Abstract
Colloidal quantum dots display remarkable optical and electrical characteristics with the potential for extensive applications in contemporary nanotechnology. As an ideal instrument for examining surface topography and local density of states (LDOS) at an atomic scale, scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) has become indispensable approaches to gain better understanding of their physical properties. This article presents a comprehensive review of the research advancements in measuring the electronic orbits and corresponding energy levels of colloidal quantum dots in various systems using STM and STS. The first three sections introduce the basic principles of colloidal quantum dots synthesis and the fundamental methodology of STM research on quantum dots. The fourth section explores the latest progress in the application of STM for colloidal quantum dot studies. Finally, a summary and prospective is presented.
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Affiliation(s)
- Jiaying Duan
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Jiapeng Wang
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Liangpeng Hou
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Peixuan Ji
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Wusheng Zhang
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Jin Liu
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Xiaodong Zhu
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Zhixiang Sun
- Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin, China, 300072
| | - Yanqing Ma
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
| | - Lei Ma
- Tianjin International Center for Nanoparticles and NanoSystems, Tianjin University, Tianjin, China, 300072
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4
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Kaiser K, Lieske LA, Repp J, Gross L. Charge-state lifetimes of single molecules on few monolayers of NaCl. Nat Commun 2023; 14:4988. [PMID: 37591847 PMCID: PMC10435478 DOI: 10.1038/s41467-023-40692-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 08/02/2023] [Indexed: 08/19/2023] Open
Abstract
In molecular tunnel junctions, where the molecule is decoupled from the electrodes by few-monolayers-thin insulating layers, resonant charge transport takes place by sequential charge transfer to and from the molecule which implies transient charging of the molecule. The corresponding charge state transitions, which involve tunneling through the insulating decoupling layers, are crucial for understanding electrically driven processes such as electroluminescence or photocurrent generation in such a geometry. Here, we use scanning tunneling microscopy to investigate the decharging of single ZnPc and H2Pc molecules through NaCl films of 3 to 5 monolayers thickness on Cu(111) and Au(111). To this end, we approach the tip to the molecule at resonant tunnel conditions up to a regime where charge transport is limited by tunneling through the NaCl film. The resulting saturation of the tunnel current is a direct measure of the lifetimes of the anionic and cationic states, i.e., the molecule's charge-state lifetime, and thus provides a means to study charge dynamics and, thereby, exciton dynamics. Comparison of anion and cation lifetimes on different substrates reveals the critical role of the level alignment with the insulator's conduction and valence band, and the metal-insulator interface state.
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Affiliation(s)
- Katharina Kaiser
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France.
| | | | - Jascha Repp
- Department of Physics, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Leo Gross
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803, Rüschlikon, Switzerland.
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5
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Hu W, Kher-Elden MA, Zhang H, Cheng P, Chen L, Piquero-Zulaica I, Abd El-Fattah ZM, Barth JV, Wu K, Zhang YQ. Engineering novel surface electronic states via complex supramolecular tessellations. NANOSCALE 2022; 14:7039-7048. [PMID: 35471409 DOI: 10.1039/d2nr00536k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Tailoring Shockley surface-state (SS) electrons utilizing complex interfacial supramolecular tessellations was explored by low-temperature scanning tunnelling microscopy and spectroscopy, combined with computational modelling using electron plane wave expansion (EPWE) and empirical tight-binding (TB) methods. Employing a recently introduced gas-mediated on-surface reaction protocol, three distinct types of open porous networks comprising paired organometallic species as basic tectons were selectively synthesized. In particular, these supramolecular networks feature semiregular Archimedean tilings, providing intricate quantum dots (QDs) coupling scenarios compared to hexagonal porous superlattices. Our experimental results in conjunction with modelling calculations demonstrate the possibility of realizing novel two-dimensional electronic structures such as Kagome- and Dirac-type as well as hybrid Kagome-type bands via QD coupling. Compared to constructing SS electron pathways via molecular manipulations, our studies reveal significant potential of exploiting QD coupling as a complementary and versatile route for the control of surface electronic landscapes.
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Affiliation(s)
- Wenqi Hu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mohammad A Kher-Elden
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City E-11884 Cairo, Egypt.
| | - Hexu Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Cheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | | | - Zakaria M Abd El-Fattah
- Physics Department, Faculty of Science, Al-Azhar University, Nasr City E-11884 Cairo, Egypt.
| | - Johannes V Barth
- Physics Department E20, Technical University of Munich, D-85748 Garching, Germany
| | - Kehui Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Yi-Qi Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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6
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Cochrane KA, Lee JH, Kastl C, Haber JB, Zhang T, Kozhakhmetov A, Robinson JA, Terrones M, Repp J, Neaton JB, Weber-Bargioni A, Schuler B. Spin-dependent vibronic response of a carbon radical ion in two-dimensional WS 2. Nat Commun 2021; 12:7287. [PMID: 34911952 PMCID: PMC8674275 DOI: 10.1038/s41467-021-27585-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 11/22/2021] [Indexed: 11/29/2022] Open
Abstract
Atomic spin centers in 2D materials are a highly anticipated building block for quantum technologies. Here, we demonstrate the creation of an effective spin-1/2 system via the atomically controlled generation of magnetic carbon radical ions (CRIs) in synthetic two-dimensional transition metal dichalcogenides. Hydrogenated carbon impurities located at chalcogen sites introduced by chemical doping are activated with atomic precision by hydrogen depassivation using a scanning probe tip. In its anionic state, the carbon impurity is computed to have a magnetic moment of 1 μB resulting from an unpaired electron populating a spin-polarized in-gap orbital. We show that the CRI defect states couple to a small number of local vibrational modes. The vibronic coupling strength critically depends on the spin state and differs for monolayer and bilayer WS2. The carbon radical ion is a surface-bound atomic defect that can be selectively introduced, features a well-understood vibronic spectrum, and is charge state controlled. Spin-polarized defects in 2D materials are attracting attention for future quantum technology applications, but their controlled fabrication is still challenging. Here, the authors report the creation and characterization of effective spin 1/2 defects via the atomically-precise generation of magnetic carbon radical ions in 2D WS2.
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Affiliation(s)
- Katherine A Cochrane
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jun-Ho Lee
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Christoph Kastl
- Walter-Schottky-Institut and Physik-Department, Technical University of Munich, Garching, 85748, Germany
| | - Jonah B Haber
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Tianyi Zhang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA.,Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Azimkhan Kozhakhmetov
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA
| | - Joshua A Robinson
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA.,Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mauricio Terrones
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16082, USA.,Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA, 16802, USA.,Department of Physics and Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, 93040, Germany
| | - Jeffrey B Neaton
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. .,Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA. .,Kavli Energy Nanosciences Institute at Berkeley, Berkeley, CA, 94720, USA.
| | | | - Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. .,nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland.
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7
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Quertite K, Enriquez H, Trcera N, Bendounan A, Mayne AJ, Dujardin G, El Kenz A, Benyoussef A, Dappe YJ, Kara A, Oughaddou H. Electron beam analysis induces Cl vacancy defects in a NaCl thin film. NANOTECHNOLOGY 2021; 33:095706. [PMID: 34814126 DOI: 10.1088/1361-6528/ac3c79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 11/23/2021] [Indexed: 06/13/2023]
Abstract
This work reports on the electron-induced modification of NaCl thin film grown on Ag(110). We show using low energy electron diffraction that electron beam bombardment leads to desorption and formation of Cl vacancy defects on NaCl surface. The topographic structure of these defects is studied using scanning tunneling microscopy (STM) showing the Cl defects as depressions on the NaCl surface. Most of the observed defects are mono-atomic vacancies and are located on flat NaCl terraces. Auger electron spectroscopy confirms the effect of electron exposure on NaCl thin films showing Cl atoms desorption from the surface. Using density functional theory taken into account the van der Waals dispersion interactions, we confirm the observed experimental STM measurements with STM simulation. Furthermore, comparing the adsorption of defect free NaCl and defective NaCl monolayer on Ag(110) surfaces, we found an increase of the adhesion energy and the charge transfer between the NaCl film and the substrate due to the Cl vacancy. In details, the adhesion energy increases between the NaCl film and the metallic Ag substrate from 30.4 meV Å-2for the NaCl film without Cl vacancy and from 39.5 meV Å-2for NaCl film with a single Cl vacancy. The charge transfer from the NaCl film to the Ag substrate is enhanced when the vacancy is created, from 0.63e-to 1.25e-.
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Affiliation(s)
- Khalid Quertite
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), Bât. 520, F-91405 Orsay, France
- Synchrotron Soleil, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette Cedex, France
- LaMCScI, Faculté des Sciences, Université Mohammed V-Agdal, 10100, Rabat, Morocco
| | - Hanna Enriquez
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), Bât. 520, F-91405 Orsay, France
| | - Nicolas Trcera
- Synchrotron Soleil, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Azzedine Bendounan
- Synchrotron Soleil, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Andrew J Mayne
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), Bât. 520, F-91405 Orsay, France
| | - Gérald Dujardin
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), Bât. 520, F-91405 Orsay, France
| | - Abdallah El Kenz
- LaMCScI, Faculté des Sciences, Université Mohammed V-Agdal, 10100, Rabat, Morocco
| | - Abdelilah Benyoussef
- LaMCScI, Faculté des Sciences, Université Mohammed V-Agdal, 10100, Rabat, Morocco
- Hassan II Academy of Sciences and Technology, Rabat, Morocco
| | - Yannick J Dappe
- Université Paris-Saclay, CEA, CNRS, SPEC, F-91191 Gif-sur-Yvette Cedex, France
| | - Abdelkader Kara
- Department of Physics, University of Central Florida, Orlando, FL 32816, United States of America
| | - Hamid Oughaddou
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), Bât. 520, F-91405 Orsay, France
- Département de Physique, CY, Cergy Paris Université, F-95031 Cergy-Pontoise Cedex, France
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8
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Yan L, Silveira OJ, Alldritt B, Kezilebieke S, Foster AS, Liljeroth P. Two-Dimensional Metal-Organic Framework on Superconducting NbSe 2. ACS NANO 2021; 15:17813-17819. [PMID: 34730941 PMCID: PMC8613900 DOI: 10.1021/acsnano.1c05986] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
The combination of two-dimensional (2D) materials into vertical heterostructures has emerged as a promising path to designer quantum materials with exotic properties. Here, we extend this concept from inorganic 2D materials to 2D metal-organic frameworks (MOFs) that offer additional flexibility in realizing designer heterostructures. We successfully fabricate a monolayer 2D Cu-dicyanoanthracene MOF on a 2D van der Waals NbSe2 superconducting substrate. The structural and electronic properties of two different phases of the 2D MOF are characterized by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), complemented by density-functional theory (DFT) calculations. These experiments allow us to follow the formation of the kagome band structure from Star of David-shaped building blocks. This work extends the synthesis and electronic tunability of 2D MOFs beyond the electronically less relevant metal and semiconducting surfaces to superconducting substrates, which are needed for the development of emerging quantum materials such as topological superconductors.
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Affiliation(s)
- Linghao Yan
- Department
of Applied Physics, Aalto University, 00076 Aalto, Finland
| | | | - Benjamin Alldritt
- Department
of Applied Physics, Aalto University, 00076 Aalto, Finland
| | | | - Adam S. Foster
- Department
of Applied Physics, Aalto University, 00076 Aalto, Finland
- Nano
Life Science Institute (WPI-NanoLSI), Kanazawa
University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Peter Liljeroth
- Department
of Applied Physics, Aalto University, 00076 Aalto, Finland
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9
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Fatayer S, Albrecht F, Tavernelli I, Persson M, Moll N, Gross L. Probing Molecular Excited States by Atomic Force Microscopy. PHYSICAL REVIEW LETTERS 2021; 126:176801. [PMID: 33988431 DOI: 10.1103/physrevlett.126.176801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 10/12/2020] [Accepted: 03/24/2021] [Indexed: 06/12/2023]
Abstract
By employing single charge injections with an atomic force microscope, we investigated redox reactions of a molecule on a multilayer insulating film. First, we charged the molecule positively by attaching a single hole. Then we neutralized it by attaching an electron and observed three channels for the neutralization. We rationalize that the three channels correspond to transitions to the neutral ground state, to the lowest energy triplet excited states and to the lowest energy singlet excited states. By single-electron tunneling spectroscopy we measured the energy differences between the transitions obtaining triplet and singlet excited state energies. The experimental values are compared with density functional theory calculations of the excited state energies. Our results show that molecules in excited states can be prepared and that energies of optical gaps can be quantified by controlled single-charge injections. Our work demonstrates the access to, and provides insight into, ubiquitous electron-attachment processes related to excited-state transitions important in electron transfer and molecular optoelectronics phenomena on surfaces.
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Affiliation(s)
- Shadi Fatayer
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Florian Albrecht
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Ivano Tavernelli
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Mats Persson
- Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool L693BX, United Kingdom
| | - Nikolaj Moll
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Leo Gross
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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10
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Luo Y, Kong FF, Tian XJ, Yu YJ, Zhang L, Chen G, Zhang Y, Zhang Y, Dong ZC. What can single-molecule Fano resonance tell? J Chem Phys 2021; 154:044309. [PMID: 33514086 DOI: 10.1063/5.0033200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In this work, we showcase applications of single-molecule Fano resonance (SMFR) measurements beyond the determination of molecular excitonic energy and associated dipole orientation. We use the SMFR measurement to probe the local influence of a man-made single chlorine vacancy on the molecular transition of a single zinc phthalocyanine, which clearly reveals the lifting-up of the double degeneracy of the excited states due to defect-induced configurational changes. Furthermore, time-trace SMFR measurements at different excitation voltages are used to track the tautomerization process in a free-base phthalocyanine. Different behaviors in switching between two inner-hydrogen configurations are observed with decreasing voltages, which helps to reveal the underlying tautomerization mechanism involving both the molecular electronic excited states and vibrational excited states in the ground state.
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Affiliation(s)
- Yang Luo
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Fan-Fang Kong
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiao-Jun Tian
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yun-Jie Yu
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Li Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Gong Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yao Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yang Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhen-Chao Dong
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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11
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Liu J, Feng X. Maßgeschneiderte Synthese von Graphennanostrukturen mit Zickzack‐Rändern. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008838] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Junzhi Liu
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry The University of Hong Kong Pokfulam Road Hong Kong China
- Center for Advancing Electronics Dresden (cfaed), und Fakultät für Chemie und Lebensmittelchemie Technische Universität Dresden 01062 Dresden Deutschland
| | - Xinliang Feng
- Center for Advancing Electronics Dresden (cfaed), und Fakultät für Chemie und Lebensmittelchemie Technische Universität Dresden 01062 Dresden Deutschland
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12
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Liu J, Feng X. Synthetic Tailoring of Graphene Nanostructures with Zigzag-Edged Topologies: Progress and Perspectives. Angew Chem Int Ed Engl 2020; 59:23386-23401. [PMID: 32720441 PMCID: PMC7756885 DOI: 10.1002/anie.202008838] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Indexed: 01/01/2023]
Abstract
Experimental and theoretical investigations have revealed that the chemical and physical properties of graphene are crucially determined by their topological structures. Therefore, the atomically precise synthesis of graphene nanostructures is essential. A particular example is graphene nanostructures with zigzag-edged structures, which exhibit unique (opto)electronic and magnetic properties owing to their spin-polarized edge state. Recent progress in the development of synthetic methods and strategies as well as characterization methods has given access to this class of unprecedented graphene nanostructures, which used to be purely molecular objectives in theoretical chemistry. Thus, clear insight into the structure-property relationships has become possible as well as new applications in organic carbon-based electronic and spintronic devices. In this Minireview, we discuss the recent progress in the controlled synthesis of zigzag-edged graphene nanostructures with different topologies through a bottom-up synthetic strategy.
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Affiliation(s)
- Junzhi Liu
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.,Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
| | - Xinliang Feng
- Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
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13
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Rothe K, Mehler A, Néel N, Kröger J. Scanning tunneling microscopy and spectroscopy of rubrene on clean and graphene-covered metal surfaces. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1157-1167. [PMID: 32821640 PMCID: PMC7418095 DOI: 10.3762/bjnano.11.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Rubrene (C42H28) was adsorbed with submonolayer coverage on Pt(111), Au(111), and graphene-covered Pt(111). Adsorption phases and vibronic properties of C42H28 consistently reflect the progressive reduction of the molecule-substrate hybridization. Separate C42H28 clusters are observed on Pt(111) as well as broad molecular resonances. On Au(111) and graphene-covered Pt(111) compact molecular islands with similar unit cells of the superstructure characterize the adsorption phase. The highest occupied molecular orbital of C42H28 on Au(111) exhibits weak vibronic progression while unoccupied molecular resonances appear with a broad line shape. In contrast, vibronic subbands are present for both frontier orbitals of C42H28 on graphene. They are due to different molecular vibrational quanta with distinct Huang-Rhys factors.
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Affiliation(s)
- Karl Rothe
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Alexander Mehler
- 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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14
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Yousofnejad A, Reecht G, Krane N, Lotze C, Franke KJ. Monolayers of MoS 2 on Ag(111) as decoupling layers for organic molecules: resolution of electronic and vibronic states of TCNQ. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1062-1071. [PMID: 32766091 PMCID: PMC7385352 DOI: 10.3762/bjnano.11.91] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/03/2020] [Indexed: 06/11/2023]
Abstract
The electronic structure of molecules on metal surfaces is largely determined by hybridization and screening by the substrate electrons. As a result, the energy levels are significantly broadened and molecular properties, such as vibrations are hidden within the spectral line shapes. Insertion of thin decoupling layers reduces the line widths and may give access to the resolution of electronic and vibronic states of an almost isolated molecule. Here, we use scanning tunneling microscopy and spectroscopy to show that a single layer of MoS2 on Ag(111) exhibits a semiconducting bandgap, which may prevent molecular states from strong interactions with the metal substrate. We show that the lowest unoccupied molecular orbital (LUMO) of tetracyanoquinodimethane (TCNQ) molecules is significantly narrower than on the bare substrate and that it is accompanied by a characteristic satellite structure. Employing simple calculations within the Franck-Condon model, we reveal their vibronic origin and identify the modes with strong electron-phonon coupling.
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Affiliation(s)
- Asieh Yousofnejad
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Gaël Reecht
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Nils Krane
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Christian Lotze
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Katharina J Franke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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15
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Tikhomirova KA, Tantardini C, Sukhanova EV, Popov ZI, Evlashin SA, Tarkhov MA, Zhdanov VL, Dudin AA, Oganov AR, Kvashnin DG, Kvashnin AG. Exotic Two-Dimensional Structure: The First Case of Hexagonal NaCl. J Phys Chem Lett 2020; 11:3821-3827. [PMID: 32330050 DOI: 10.1021/acs.jpclett.0c00874] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
NaCl is one of the simplest compounds and was thought to be well-understood, and yet, unexpected complexities related to it were uncovered at high pressure and in low-dimensional states. Here, exotic hexagonal NaCl thin films on the (110) diamond surface were crystallized in the experiment following a theoretical prediction based on ab initio evolutionary algorithm USPEX. State-of-the-art calculations and experiments showed the existence of a hexagonal NaCl thin film, which is due to the strong chemical interaction of the NaCl film with the diamond substrate.
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Affiliation(s)
- Kseniya A Tikhomirova
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
| | - Christian Tantardini
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
| | - Ekaterina V Sukhanova
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow 119334, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny 141700, Russia
| | - Zakhar I Popov
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow 119334, Russia
| | - Stanislav A Evlashin
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
| | - Mikhail A Tarkhov
- Institute of Nanotechnologies of Microelectronics of the Russian Academy of Sciences, 32 A Leninsky Prospekt, Moscow 119991, Russia
| | | | - Alexander A Dudin
- Institute of Nanotechnologies of Microelectronics of the Russian Academy of Sciences, 32 A Leninsky Prospekt, Moscow 119991, Russia
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny 141700, Russia
- International Center for Materials Discovery, Northwestern Polytechnical University, Xi'an 710072, China
| | - Dmitry G Kvashnin
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow 119334, Russia
- Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny 141700, Russia
| | - Alexander G Kvashnin
- Skolkovo Institute of Science and Technology, 30, bld. 1 Bolshoy Boulevard, Moscow 121205, Russia
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16
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Fatayer S, Albrecht F, Zhang Y, Urbonas D, Peña D, Moll N, Gross L. Molecular structure elucidation with charge-state control. SCIENCE (NEW YORK, N.Y.) 2020; 365:142-145. [PMID: 31296763 DOI: 10.1126/science.aax5895] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/12/2019] [Indexed: 11/02/2022]
Abstract
The charge state of a molecule governs its physicochemical properties, such as conformation, reactivity, and aromaticity, with implications for on-surface synthesis, catalysis, photoconversion, and applications in molecular electronics. On insulating, multilayer sodium chloride (NaCl) films, we controlled the charge state of organic molecules and resolved their structures in neutral, cationic, anionic, and dianionic states by atomic force microscopy, obtaining atomic resolution and bond-order discrimination using carbon monoxide (CO)-functionalized tips. We detected changes in conformation, adsorption geometry, and bond-order relations for azobenzene, tetracyanoquinodimethane, and pentacene in multiple charge states. Moreover, for porphine, we investigate the charge state-dependent change of aromaticity and conjugation pathway in the macrocycle. This work opens the way to studying chemical-structural changes of individual molecules for a wide range of charge states.
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Affiliation(s)
| | | | - Yunlong Zhang
- ExxonMobil Research and Engineering Company, Annandale, NJ 08801, USA
| | | | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Nikolaj Moll
- IBM Research-Zurich, Rueschlikon 8803, Switzerland
| | - Leo Gross
- IBM Research-Zurich, Rueschlikon 8803, Switzerland.
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17
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Reecht G, Krane N, Lotze C, Zhang L, Briseno AL, Franke KJ. Vibrational Excitation Mechanism in Tunneling Spectroscopy beyond the Franck-Condon Model. PHYSICAL REVIEW LETTERS 2020; 124:116804. [PMID: 32242680 DOI: 10.1103/physrevlett.124.116804] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 01/22/2020] [Accepted: 02/21/2020] [Indexed: 06/11/2023]
Abstract
Vibronic spectra of molecules are typically described within the Franck-Condon model. Here, we show that highly resolved vibronic spectra of large organic molecules on a single layer of MoS_{2} on Au(111) show spatial variations in their intensities, which cannot be captured within this picture. We explain that vibrationally mediated perturbations of the molecular wave functions need to be included into the Franck-Condon model. Our simple model calculations reproduce the experimental spectra at arbitrary position of the scanning tunneling microscope's tip over the molecule in great detail.
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Affiliation(s)
- Gaël Reecht
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Nils Krane
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Christian Lotze
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Lei Zhang
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Alejandro L Briseno
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Katharina J Franke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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18
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Kvashnin AG, Kvashnin DG, Oganov AR. Novel Unexpected Reconstructions of (100) and (111) Surfaces of NaCl: Theoretical Prediction. Sci Rep 2019; 9:14267. [PMID: 31582761 PMCID: PMC6776646 DOI: 10.1038/s41598-019-50548-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 09/12/2019] [Indexed: 11/09/2022] Open
Abstract
We have predicted stable reconstructions of the (100) and (111) surfaces of NaCl using the global optimization algorithm USPEX. Several new reconstructions, together with the previously reported ones, are found. For the cleaved bare (100) surface, pure Na and pure Cl are the only stable surface phases. Our study of the (111) surface shows that a newly predicted Na3Cl-(1 × 1) reconstruction is thermodynamically stable in a wide range of chlorine chemical potentials. It has a sawtooth-like profile where each facet reproduces the (100) surface of rock-salt NaCl, hinting on the preferred growth of the (100) surface. We used Bader charge analysis to explain the preferable formation of this sawtooth-like Na3Cl-(1 × 1) reconstruction of the (111) surface of NaCl. We find that at a very high chemical potential of Na, the polar (and normally absent) (111) surface becomes part of the equilibrium crystal morphology. At both very high and very low chemical potentials of Cl, we predict a large decrease of surface energy and fracture toughness (the Rehbinder effect).
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Affiliation(s)
- Alexander G Kvashnin
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 121205, Russia.,Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny, 141700, Russia
| | - Dmitry G Kvashnin
- Emanuel Institute of Biochemical Physics RAS, 4 Kosigina Street, Moscow, 119334, Russia. .,National University of Science and Technology MISIS, 4 Leninskiy Prospekt, Moscow, 119049, Russia.
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow, 121205, Russia.,Moscow Institute of Physics and Technology, 9 Institutsky Pereulok, Dolgoprudny, 141700, Russia.,International Center for Materials Discovery, Northwestern Polytechnical University, Xi'an, 710072, China
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19
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Schuler B, Qiu DY, Refaely-Abramson S, Kastl C, Chen CT, Barja S, Koch RJ, Ogletree DF, Aloni S, Schwartzberg AM, Neaton JB, Louie SG, Weber-Bargioni A. Large Spin-Orbit Splitting of Deep In-Gap Defect States of Engineered Sulfur Vacancies in Monolayer WS_{2}. PHYSICAL REVIEW LETTERS 2019; 123:076801. [PMID: 31491121 DOI: 10.1103/physrevlett.123.076801] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 05/29/2019] [Indexed: 06/10/2023]
Abstract
Structural defects in 2D materials offer an effective way to engineer new material functionalities beyond conventional doping. We report on the direct experimental correlation of the atomic and electronic structure of a sulfur vacancy in monolayer WS_{2} by a combination of CO-tip noncontact atomic force microscopy and scanning tunneling microscopy. Sulfur vacancies, which are absent in as-grown samples, were deliberately created by annealing in vacuum. Two energetically narrow unoccupied defect states followed by vibronic sidebands provide a unique fingerprint of this defect. Direct imaging of the defect orbitals, together with ab initio GW calculations, reveal that the large splitting of 252±4 meV between these defect states is induced by spin-orbit coupling.
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Affiliation(s)
- Bruno Schuler
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Diana Y Qiu
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sivan Refaely-Abramson
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Christoph Kastl
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Walter Schottky Institute and Physics Department, Technical University of Munich, 85748 Garching, Germany
| | - Christopher T Chen
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sara Barja
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Departamento de Física de Materiales, Centro de Física de Materiales, University of the Basque Country UPV/EHU-CSIC, Donostia-San Sebastián 20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao 48013, Spain
- Donostia International Physics Center, Donostia-San Sebastin 20018, Spain
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - D Frank Ogletree
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Adam M Schwartzberg
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey B Neaton
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Kavli Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, USA
| | - Steven G Louie
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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20
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Kaiser K, Scriven LM, Schulz F, Gawel P, Gross L, Anderson HL. An sp-hybridized molecular carbon allotrope, cyclo[18]carbon. Science 2019; 365:1299-1301. [DOI: 10.1126/science.aay1914] [Citation(s) in RCA: 277] [Impact Index Per Article: 55.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/02/2019] [Indexed: 01/25/2023]
Abstract
Carbon allotropes built from rings of two-coordinate atoms, known as cyclo[n]carbons, have fascinated chemists for many years, but until now they could not be isolated or structurally characterized because of their high reactivity. We generated cyclo[18]carbon (C18) using atom manipulation on bilayer NaCl on Cu(111) at 5 kelvin by eliminating carbon monoxide from a cyclocarbon oxide molecule, C24O6. Characterization of cyclo[18]carbon by high-resolution atomic force microscopy revealed a polyynic structure with defined positions of alternating triple and single bonds. The high reactivity of cyclocarbon and cyclocarbon oxides allows covalent coupling between molecules to be induced by atom manipulation, opening an avenue for the synthesis of other carbon allotropes and carbon-rich materials from the coalescence of cyclocarbon molecules.
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21
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Selective triplet exciton formation in a single molecule. Nature 2019; 570:210-213. [DOI: 10.1038/s41586-019-1284-2] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 04/02/2019] [Indexed: 11/08/2022]
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22
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Miwa K, Imada H, Imai-Imada M, Kimura K, Galperin M, Kim Y. Many-Body State Description of Single-Molecule Electroluminescence Driven by a Scanning Tunneling Microscope. NANO LETTERS 2019; 19:2803-2811. [PMID: 30694065 DOI: 10.1021/acs.nanolett.8b04484] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention because of their scientific importance and potential applications. With the recent progress in experimental techniques, especially by virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it has become possible to investigate single-molecule properties at subnanometer spatial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission has yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body state representation of the molecule. The effects of intramolecular Coulomb interaction on conductance and luminescence spectra are investigated using the nonequilibrium Hubbard Green's function technique combined with first-principles calculations. We compare simulation results with experimental data and find that the intramolecular Coulomb interaction is crucial for reproducing recent experiments for a single phthalocyanine molecule. The developed theory provides a unified description of the electron transport and optical properties of a single molecule in contact with metal electrodes driven out of equilibrium, and thereby, it contributes to a microscopic understanding of optoelectronic conversion in single molecules on solid surfaces and in nanometer-scale junctions.
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Affiliation(s)
- Kuniyuki Miwa
- Surface and Interface Science Laboratory , RIKEN , Wako , Saitama 351-0198 , Japan
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Hiroshi Imada
- Surface and Interface Science Laboratory , RIKEN , Wako , Saitama 351-0198 , Japan
| | - Miyabi Imai-Imada
- Surface and Interface Science Laboratory , RIKEN , Wako , Saitama 351-0198 , Japan
- Department of Advanced Materials Science, Graduate School of Frontier Science , The University of Tokyo , Kashiwa , Chiba 277-8651 , Japan
| | - Kensuke Kimura
- Surface and Interface Science Laboratory , RIKEN , Wako , Saitama 351-0198 , Japan
- Department of Advanced Materials Science, Graduate School of Frontier Science , The University of Tokyo , Kashiwa , Chiba 277-8651 , Japan
| | - Michael Galperin
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Yousoo Kim
- Surface and Interface Science Laboratory , RIKEN , Wako , Saitama 351-0198 , Japan
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23
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Ren J, Wang Y, Zhao J, Tan S, Petek H. K Atom Promotion of O2 Chemisorption on Au(111) Surface. J Am Chem Soc 2019; 141:4438-4444. [DOI: 10.1021/jacs.8b13843] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Jindong Ren
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Yanan Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Materials for Energy Conversion and Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026, P. R. China
| | - Jin Zhao
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Materials for Energy Conversion and Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026, P. R. China
| | - Shijing Tan
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Hrvoje Petek
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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24
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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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25
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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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26
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Gross L, Schuler B, Pavliček N, Fatayer S, Majzik Z, Moll N, Peña D, Meyer G. Rasterkraftmikroskopie für die molekulare Strukturaufklärung. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201703509] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Leo Gross
- IBM Research - Zürich; 8803 Rüschlikon Schweiz
| | - Bruno Schuler
- IBM Research - Zürich; 8803 Rüschlikon Schweiz
- Molecular Foundry; Lawrence Berkeley National Laboratory; Berkeley CA 94720 USA
| | | | | | | | | | - 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 Spanien
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27
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Gross L, Schuler B, Pavliček N, Fatayer S, Majzik Z, Moll N, Peña D, Meyer G. Atomic Force Microscopy for Molecular Structure Elucidation. Angew Chem Int Ed Engl 2018; 57:3888-3908. [DOI: 10.1002/anie.201703509] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/14/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Leo Gross
- IBM Research-Zurich; 8803 Rüschlikon Switzerland
| | - Bruno Schuler
- IBM Research-Zurich; 8803 Rüschlikon Switzerland
- Current address: Molecular Foundry; Lawrence Berkeley National Laboratory; Berkeley CA 94720 USA
| | | | | | - Zsolt Majzik
- IBM Research-Zurich; 8803 Rüschlikon Switzerland
| | - Nikolaj Moll
- IBM Research-Zurich; 8803 Rüschlikon Switzerland
| | - 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
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28
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Xu C, Que Y, Zhuang Y, Lin Z, Wu X, Wang K, Xiao X. Growth Behavior of Pristine and Potassium Doped Coronene Thin Films on Substrates with Tuned Coupling Strength. J Phys Chem B 2018; 122:601-611. [PMID: 28862462 DOI: 10.1021/acs.jpcb.7b05140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The growth of polycyclic aromatic hydrocarbon (PAH) molecular coronene film on various substrates and the subsequent doping of potassium under ultrahigh vacuum (UHV) conditions have been systematically investigated by low-temperature scanning tunneling microscopy and spectroscopy (STM/STS). The crystalline structures and molecular orientations of coronene thin films are both thickness-dependent and substrate-sensitive due to the competition between molecule-substrate interaction and intermolecular interaction. In mono- or bilayer films, coronene molecules are flat-lying on the surface with hexagonal lattice, whereas in multilayer films, the topmost molecules are in a standing-up but tilted configuration with rectangular lattice. In particular, a 2 × 1 superstructure with respect to that of bulk coronene is formed on thick KCl film. Furthermore, we have studied the potassium doped coronene monolayer and multilayer on Ag(100) and KCl/Ag(100) surface. For K-doped coronene monolayer, at certain doping ratio x = 3, the lowest unoccupied molecular orbital (LUMO) of coronene film moves to the Fermi level, and a splitting of the LUMO state is observed. Increased potassium doping would result in a filled LUMO state below the Fermi level. By contrast, no well-ordered structures are obtained in the K-doped coronene multilayers which are vulnerable to rather moderate annealing processes owing to their relatively weak bonding with the supporting substrates, implying a big challenge of growth of PAH thick films in vacuum. The differences in the crystal structures of coronene thin films compared with that in bulk crystals might shed insight on the controversies in the experimental results on the electronic properties of alkali-metal-doped PAHs.
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Affiliation(s)
- Chaoqiang Xu
- Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong China
| | - Yande Que
- Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong China
| | - Yuan Zhuang
- Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong China
| | - Zhijun Lin
- Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong China
| | - Xuefeng Wu
- Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong China.,Department of Physics, Southern University of Science and Technology , Shenzhen, Guangdong 518055, People's Republic of China
| | - Kedong Wang
- Department of Physics, Southern University of Science and Technology , Shenzhen, Guangdong 518055, People's Republic of China
| | - Xudong Xiao
- Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong China
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29
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Folkertsma E, van der Lit J, Di Cicco F, Lutz M, Klein Gebbink RJM, Swart I, Moret ME. Combination of Scanning Probe Microscopy and Coordination Chemistry: Structural and Electronic Study of Bis(methylbenzimidazolyl)ketone and Its Iron Complex. ACS OMEGA 2017; 2:1372-1379. [PMID: 28474011 PMCID: PMC5410654 DOI: 10.1021/acsomega.6b00510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/23/2017] [Indexed: 06/07/2023]
Abstract
Here, we report the bulk synthesis of [FeII(BMBIK)Cl2] bearing the redox noninnocent bis(methylbenzimidazolyl)ketone (BMBIK) ligand and the synthesis of the similar complex [FeI(BMBIK)]+ on a Au(111) surface using lateral manipulation at the atomic level. Cyclic voltammetry and scanning tunneling spectroscopy are shown to be useful techniques to compare the coordination compound in solution with the one on the surface. The total charge, as well as the oxidation and spin state of [FeI(BMBIK)]+, are investigated by comparison of the shape of the lowest unoccupied molecular orbital (LUMO), visualized by tunneling through the LUMO, with theoretical models. The similar reduction potentials found for the solution and surface compounds indicate that the major effect of lowering the LUMO upon coordination of BMBIK to the iron center is conserved on the surface. The synthesis and analysis of [FeI(BMBIK)]+ using scanning tunneling microscopy, scanning tunneling spectroscopy, and atomic force microscopy are the first steps toward mechanistic studies of homogeneous catalysts with redox noninnocent ligands at the single molecule level.
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Affiliation(s)
- Emma Folkertsma
- Organic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Joost van der Lit
- Condensed
Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O.
Box 80000, 3508 TA Utrecht, The Netherlands
| | - Francesca Di Cicco
- Condensed
Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O.
Box 80000, 3508 TA Utrecht, The Netherlands
| | - Martin Lutz
- Crystal
and Structural Chemistry, Bijvoet Center for Biomolecular Research,
Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Robertus J. M. Klein Gebbink
- Organic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Ingmar Swart
- Condensed
Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, P.O.
Box 80000, 3508 TA Utrecht, The Netherlands
| | - Marc-Etienne Moret
- Organic
Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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30
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Guo J, Bian K, Lin Z, Jiang Y. Perspective: Structure and dynamics of water at surfaces probed by scanning tunneling microscopy and spectroscopy. J Chem Phys 2017; 145:160901. [PMID: 27802647 DOI: 10.1063/1.4964668] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The detailed and precise understanding of water-solid interaction largely relies on the development of atomic-scale experimental techniques, among which scanning tunneling microscopy (STM) has proven to be a noteworthy example. In this perspective, we review the recent advances of STM techniques in imaging, spectroscopy, and manipulation of water molecules. We discuss how those newly developed techniques are applied to probe the structure and dynamics of water at solid surfaces with single-molecule and even submolecular resolution, paying particular attention to the ability of accessing the degree of freedom of hydrogen. In the end, we present an outlook on the directions of future STM studies of water-solid interfaces as well as the challenges faced by this field. Some new scanning probe techniques beyond STM are also envisaged.
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Affiliation(s)
- Jing Guo
- International Center for Quantum Materials, 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
| | - Zeren Lin
- 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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31
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Nanographenes and Graphene Nanoribbons with Zigzag-Edged Structures. ADVANCES IN POLYMER SCIENCE 2017. [DOI: 10.1007/12_2017_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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32
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Li Z, Chen HYT, Schouteden K, Picot T, Houben K, Liao TW, Van Haesendonck C, Pacchioni G, Lievens P, Janssens E. Size-Dependent Penetration of Gold Nanoclusters through a Defect-Free, Nonporous NaCl Membrane. NANO LETTERS 2016; 16:3063-3070. [PMID: 27074132 DOI: 10.1021/acs.nanolett.6b00126] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Membranes and their size-selective filtering properties are universal in nature and their behavior is exploited to design artificial membranes suited for, e.g., molecule or nanoparticle filtering and separation. Exploring and understanding penetration and transmission mechanisms of nanoparticles in thin-film systems may provide new opportunities for size selective deposition or embedding of the nanoparticles. Here, we demonstrate an unexpected finding that the sieving of metal nanoparticles through atomically thin nonporous alkali halide films on a metal support is size dependent and that this sieving effect can be tuned via the film thickness. Specifically, relying on scanning tunneling microscopy and spectroscopy techniques, combined with density functional theory calculations, we find that defect-free NaCl films on a Au(111) support act as size-dependent membranes for deposited Au nanoclusters. The observed sieving ability is found to originate from a driving force toward the metal support and from the dynamics of both the nanoparticles and the alkali halide films.
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Affiliation(s)
- Zhe Li
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Hsin-Yi Tiffany Chen
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
| | - Koen Schouteden
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Thomas Picot
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Kelly Houben
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Ting-Wei Liao
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Chris Van Haesendonck
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Gianfranco Pacchioni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca , Via Cozzi 55, I-20125 Milano, Italy
| | - Peter Lievens
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
| | - Ewald Janssens
- Laboratory of Solid-State Physics and Magnetism, KU Leuven , Celestijnenlaan 200 d, box 2414, BE-3001 Leuven, Belgium
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33
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Ellner M, Pavliček N, Pou P, Schuler B, Moll N, Meyer G, Gross L, Peréz R. The Electric Field of CO Tips and Its Relevance for Atomic Force Microscopy. NANO LETTERS 2016; 16:1974-1980. [PMID: 26840626 DOI: 10.1021/acs.nanolett.5b05251] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Metal tips decorated with CO molecules have paved the way for an impressively high resolution in atomic force microscopy (AFM). Although Pauli repulsion and the associated CO tilting play a dominant role at short distances, experiments on polar and metallic systems show that electrostatic interactions are necessary to understand the complex contrast observed and its distance evolution. Attempts to describe those interactions in terms of a single electrostatic dipole replacing the tip have led to contradictory statements about its nature and strength. Here, we solve this puzzle with a comprehensive experimental and theoretical characterization of the AFM contrast on Cl vacancies. Our model, based on density functional theory (DFT) calculations, reproduces the complex evolution of the contrast between both the Na cation and Cl anion sites, and the positively charged vacancy as a function of tip height, and highlights the key contribution of electrostatic interactions for tip-sample distances larger than 500 pm. For smaller separations, Pauli repulsion and the associated CO tilting start to dominate the contrast. The electrostatic field of the CO-metal tip can be represented by the superposition of the fields from the metal tip and the CO molecule. The long-range behavior is defined by the metal tip that contributes the field of a dipole with its positive pole at the apex. At short-range, the CO exhibits an opposite field that prevails. The interplay of these fields, with opposite sign and rather different spatial extension, is crucial to describe the contrast evolution as a function of the tip height.
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Affiliation(s)
- Michael Ellner
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid , E-28049 Madrid, Spain
| | | | - Pablo Pou
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid , E-28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , E-28049 Madrid, Spain
| | | | - Nikolaj Moll
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
| | | | - Leo Gross
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
| | - Rubén Peréz
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid , E-28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , E-28049 Madrid, Spain
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34
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Néel N, Lattelais M, Bocquet ML, Kröger J. Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene. ACS NANO 2016; 10:2010-6. [PMID: 26812093 DOI: 10.1021/acsnano.5b06153] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Single-molecule chemistry with a scanning tunneling microscope has preponderantly been performed on metal surfaces. The molecule-metal hybridization, however, is often detrimental to genuine molecular properties and obscures their changes upon chemical reactions. We used graphene on Ir(111) to reduce the coupling between Ir(111) and adsorbed phthalocyanine molecules. By local electron injection from the tip of a scanning tunneling microscope the two pyrrolic H atoms were removed from single phthalocyanines. The detachment of the H atom pair induced a strong modification of the molecular electronic structure, albeit with no change in the adsorption geometry. Spectra and maps of the differential conductance combined with density functional calculations unveiled the entire depopulation of the highest occupied molecular orbital upon H abstraction. Occupied π states of intact molecules are proposed to be emptied via intramolecular electron transfer to dangling σ states of H-free N atoms.
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Affiliation(s)
- Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - Marie Lattelais
- Department of Chemistry, UMR ENS-CNRS-UPMC 8640, Ecole Normale Supérieure , F-75005 Paris, France
| | - Marie-Laure Bocquet
- Department of Chemistry, UMR ENS-CNRS-UPMC 8640, Ecole Normale Supérieure , F-75005 Paris, France
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
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35
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Wong D, Velasco J, Ju L, Lee J, Kahn S, Tsai HZ, Germany C, Taniguchi T, Watanabe K, Zettl A, Wang F, Crommie MF. Characterization and manipulation of individual defects in insulating hexagonal boron nitride using scanning tunnelling microscopy. NATURE NANOTECHNOLOGY 2015; 10:949-53. [PMID: 26301901 DOI: 10.1038/nnano.2015.188] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 07/21/2015] [Indexed: 05/24/2023]
Abstract
Defects play a key role in determining the properties and technological applications of nanoscale materials and, because they tend to be highly localized, characterizing them at the single-defect level is of particular importance. Scanning tunnelling microscopy has long been used to image the electronic structure of individual point defects in conductors, semiconductors and ultrathin films, but such single-defect electronic characterization remains an elusive goal for intrinsic bulk insulators. Here, we show that individual native defects in an intrinsic bulk hexagonal boron nitride insulator can be characterized and manipulated using a scanning tunnelling microscope. This would typically be impossible due to the lack of a conducting drain path for electrical current. We overcome this problem by using a graphene/boron nitride heterostructure, which exploits the atomically thin nature of graphene to allow the visualization of defect phenomena in the underlying bulk boron nitride. We observe three different defect structures that we attribute to defects within the bulk insulating boron nitride. Using scanning tunnelling spectroscopy we obtain charge and energy-level information for these boron nitride defect structures. We also show that it is possible to manipulate the defects through voltage pulses applied to the scanning tunnelling microscope tip.
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Affiliation(s)
- Dillon Wong
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Jairo Velasco
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Long Ju
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Juwon Lee
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Salman Kahn
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Hsin-Zon Tsai
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Chad Germany
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Alex Zettl
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Feng Wang
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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36
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Steurer W, Fatayer S, Gross L, Meyer G. Probe-based measurement of lateral single-electron transfer between individual molecules. Nat Commun 2015; 6:8353. [PMID: 26387533 PMCID: PMC4595756 DOI: 10.1038/ncomms9353] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 08/14/2015] [Indexed: 11/09/2022] Open
Abstract
The field of molecular electronics aims at using single molecules as functional building blocks for electronics components, such as switches, rectifiers or transistors. A key challenge is to perform measurements with atomistic control over the alignment of the molecule and its contacting electrodes. Here we use atomic force microscopy to examine charge transfer between weakly coupled pentacene molecules on insulating films with single-electron sensitivity and control over the atomistic details. We show that, in addition to the imaging capability, the probe tip can be used to control the charge state of individual molecules and to detect charge transfers to/from the tip, as well as between individual molecules. Our approach represents a novel route for molecular charge transfer studies with a host of opportunities, especially in combination with single atom/molecule manipulation and nanopatterning techniques.
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Affiliation(s)
| | | | - Leo Gross
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
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37
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Stiehler C, Calaza F, Schneider WD, Nilius N, Freund HJ. Molecular Adsorption Changes the Quantum Structure of Oxide-Supported Gold Nanoparticles: Chemisorption versus Physisorption. PHYSICAL REVIEW LETTERS 2015; 115:036804. [PMID: 26230817 DOI: 10.1103/physrevlett.115.036804] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Indexed: 06/04/2023]
Abstract
STM conductance spectroscopy and mapping has been used to analyze the impact of molecular adsorption on the quantized electronic structure of individual metal nanoparticles. For this purpose, isophorone and CO2, as prototype molecules for physisorptive and chemisorptive binding, were dosed onto monolayer Au islands grown on MgO thin films. The molecules attach exclusively to the metal-oxide boundary, while the interior of the islands remains pristine. The Au quantum well states are perturbed due to the adsorption process and increase their mutual energy spacing in the CO2 case but move together in isophorone-covered islands. The shifts disclose the nature of the molecule-Au interaction, which relies on electron exchange for the CO2 ligands but on dispersive forces for the organic species. Our experiments reveal how molecular adsorption affects individual quantum systems, a topic of utmost relevance for heterogeneous catalysis.
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Affiliation(s)
| | - Florencia Calaza
- Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany
| | - Wolf-Dieter Schneider
- Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany
- Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Niklas Nilius
- Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany
- Carl von Ossietzky Universität, 26111 Oldenburg, Germany
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38
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Li Z, Chen HYT, Schouteden K, Lauwaet K, Janssens E, Van Haesendonck C, Pacchioni G, Lievens P. Lateral manipulation of atomic vacancies in ultrathin insulating films. ACS NANO 2015; 9:5318-5325. [PMID: 25769024 DOI: 10.1021/acsnano.5b00840] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
During the last 20 years, using scanning tunneling microscopy (STM) and atomic force microscopy, scientists have successfully achieved vertical and lateral repositioning of individual atoms on and in different types of surfaces. Such atom manipulation allows the bottom-up assembly of novel nanostructures that can otherwise not be fabricated. It is therefore surprising that controlled repositioning of virtual atoms, i.e., atomic vacancies, across atomic lattices has not yet been achieved experimentally. Here we use STM at liquid helium temperature (4.5 K) to create individual Cl vacancies and subsequently to laterally manipulate them across the surface of ultrathin sodium chloride films. This allows monitoring the interactions between two neighboring vacancies with different separations. Our findings are corroborated by density functional theory calculations and STM image simulations. The lateral manipulation of atomic vacancies opens up a new playground for the investigation of fundamental physical properties of vacancy nanostructures of any size and shape and their coupling with the supporting substrate, and of the interaction of various deposits with charged vacancies.
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Affiliation(s)
- Zhe Li
- †Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 d, Box 2414, BE-3001 Leuven, Belgium
| | - Hsin-Yi Tiffany Chen
- ‡Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 55, I-20125 Milano, Italy
| | - Koen Schouteden
- †Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 d, Box 2414, BE-3001 Leuven, Belgium
| | - Koen Lauwaet
- †Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 d, Box 2414, BE-3001 Leuven, Belgium
| | - Ewald Janssens
- †Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 d, Box 2414, BE-3001 Leuven, Belgium
| | - Chris Van Haesendonck
- †Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 d, Box 2414, BE-3001 Leuven, Belgium
| | - Gianfranco Pacchioni
- ‡Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 55, I-20125 Milano, Italy
| | - Peter Lievens
- †Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200 d, Box 2414, BE-3001 Leuven, Belgium
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39
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Gross L, Schuler B, Mohn F, Moll N, Repp J, Meyer G. Atomic Resolution on Molecules with Functionalized Tips. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/978-3-319-15588-3_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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40
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Cui Y, Tosoni S, Schneider WD, Pacchioni G, Nilius N, Freund HJ. Phonon-mediated electron transport through CaO thin films. PHYSICAL REVIEW LETTERS 2015; 114:016804. [PMID: 25615494 DOI: 10.1103/physrevlett.114.016804] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Indexed: 06/04/2023]
Abstract
Scanning tunneling microscopy has developed into a powerful tool for the characterization of conductive surfaces, for which the overlap of tip and sample wave functions determines the image contrast. On insulating layers, as the CaO thin film grown on Mo(001) investigated here, direct overlap between initial and final states is not enabled anymore and electrons are transported via hopping through the conduction-band states of the oxide. Carrier transport is accompanied by strong phonon excitations in this case, imprinting an oscillatory signature on the differential conductance spectra of the system. The phonons show a characteristic spatial dependence and become softer around lattice irregularities in the oxide film, such as dislocation lines.
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Affiliation(s)
- Yi Cui
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - Sergio Tosoni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 53, 20125 Milano, Italy
| | - Wolf-Dieter Schneider
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany and Ecole Polytechnique Fédérale de Lausanne, Institute of Physics, CH-1015 Lausanne, Switzerland
| | - Gianfranco Pacchioni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via Cozzi 53, 20125 Milano, Italy
| | - Niklas Nilius
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany and Carl von Ossietzky Universität Oldenburg, Institut für Physik, D-26111 Oldenburg, Germany
| | - Hans-Joachim Freund
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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41
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Sumpter BG, Liang L, Nicolaï A, Meunier V. Interfacial properties and design of functional energy materials. Acc Chem Res 2014; 47:3395-405. [PMID: 24963787 DOI: 10.1021/ar500180h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
CONSPECTUS: The vital importance of energy to society continues to demand a relentless pursuit of energy responsive materials that can bridge fundamental chemical structures at the molecular level and achieve improved functionality and performance. This demand can potentially be realized by harnessing the power of self-assembly, a spontaneous process where molecules or much larger entities form ordered aggregates as a consequence of predominately noncovalent (weak) interactions. Self-assembly is the key to bottom-up design of molecular devices, because the nearly atomic-level control is very difficult to realize in a top-down, for example, lithographic, approach. However, while function in simple systems such as single crystals can often be evaluated a priori, predicting the function of the great variety of self-assembled molecular architectures is complicated by the lack of understanding and control over nanoscale interactions, mesoscale architectures, and macroscale order. To establish a foundation toward delivering practical solutions, it is critical to develop an understanding of the chemical and physical mechanisms responsible for the self-assembly of molecular and hybrid materials on various support substrates. Typical molecular self-assembly involves noncovalent intermolecular and substrate-molecule interactions. These interactions remain poorly understood, due to the combination of many-body interactions compounded by local or collective influences from the substrate atomic lattice and electronic structure. Progress toward unraveling the underlying physicochemical processes that control the structure and macroscopic physical, chemical, mechanical, electrical, and transport properties of materials increasingly requires tight integration of theory, modeling, and simulation with precision synthesis, advanced experimental characterization, and device measurements. Theory, modeling, and simulation can accelerate the process of materials understanding and design by providing atomic level understanding of the underlying physicochemical phenomena (illuminating connections between experiments). It can also provide the ability to explore new materials and conditions before they are realized in the laboratory. With tight integration and feedback with experiment, it becomes feasible to identify promising materials or processes for targeted energy applications. In this Account, we highlight recent advances and success in using an integrated approach based on electronic structure simulations and scanning probe microscopy techniques to study and design functional materials formed from the self-assembly of molecules into supramolecular or polymeric architectures on substrates.
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Affiliation(s)
- Bobby G. Sumpter
- Center for Nanophase Materials Sciences and Computer Science & Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Liangbo Liang
- Department
of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Adrien Nicolaï
- Department
of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Vincent Meunier
- Department
of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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42
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Suich DE, Caplins BW, Shearer AJ, Harris CB. Femtosecond Trapping of Free Electrons in Ultrathin Films of NaCl on Ag(100). J Phys Chem Lett 2014; 5:3073-3077. [PMID: 26278263 DOI: 10.1021/jz501572z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the excited-state electron dynamics for ultrathin films of NaCl on Ag(100). The first three image potential states (IPSs) were initially observed following excitation. The electrons in the spatially delocalized n = 1 IPS decayed on the ultrafast time scale into multiple spatially localized states lower in energy. The localized electronic states are proposed to correspond to electrons trapped at defects in the NaCl islands. Coverage and temperature dependence of the localized states support the assignment to surface trap states existing at the NaCl/vacuum interface. These results highlight the importance of electron trapping in ultrathin insulating layers.
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Affiliation(s)
- David E Suich
- Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States
| | - Benjamin W Caplins
- Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States
| | - Alex J Shearer
- Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States
| | - Charles B Harris
- Department of Chemistry, University of California at Berkeley, 419 Latimer Hall, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States
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43
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Vonau F, Shokri R, Aubel D, Bouteiller L, Guskova O, Sommer JU, Reiter G, Simon L. Tunneling spectroscopy measurements on hydrogen-bonded supramolecular polymers. NANOSCALE 2014; 6:8250-8256. [PMID: 24930672 DOI: 10.1039/c4nr00539b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We studied the formation of hydrogen-bonded supramolecular polymers of Ethyl Hexyl Urea Toluene (EHUT) on a gold (111) surface by low temperature scanning tunneling microscopy. Tunneling spectroscopy performed along an individual molecule embedded in a self-assembled layer revealed strong changes in the value of the HOMO-LUMO gap. A variation of the LUMO state is attributed to the effect of space charge accumulation resulting from anisotropic adhesion of the molecule. In addition, for specific tunneling conditions, changes induced through the formation of hydrogen bonds became visible in the differential conductance (dI/dV) maps; isolated molecules, hydrogen bonded dimers and supramolecular polymers of EHUT were distinguishable through their electronic properties.
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Affiliation(s)
- François Vonau
- Institut des Sciences de Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace, 3B, rue Alfred Werner, 68093 Mulhouse, France.
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44
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Tahir M, MacKinnon A, Schwingenschlögl U. Novel spectral features of nanoelectromechanical systems. Sci Rep 2014; 4:4035. [PMID: 24531805 PMCID: PMC3925967 DOI: 10.1038/srep04035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/24/2014] [Indexed: 12/03/2022] Open
Abstract
Electron transport through a quantum dot or single molecule coupled to a quantum oscillator is studied by the Keldysh nonequilibrium Green's function formalism to obtain insight into the quantum dynamics of the electronic and oscillator degrees of freedom. We tune the electronic level of the quantum dot by a gate voltage, where the leads are kept at zero temperature. Due to the nonequilibrium distribution of the electrons in the quantum dot, the spectral function becomes a function of the gate voltage. Novel spectral features are identified for the ground and excited states of nanomechanical oscillators that can be used to enhance the measurement sensitivity.
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Affiliation(s)
- M. Tahir
- PSE Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - A. MacKinnon
- Department of Physics, The Blackett Laboratory, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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45
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Wang H, Amsalem P, Heimel G, Salzmann I, Koch N, Oehzelt M. Band-bending in organic semiconductors: the role of alkali-halide interlayers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:925-930. [PMID: 24338797 DOI: 10.1002/adma.201303467] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/25/2013] [Indexed: 05/28/2023]
Abstract
Band-bending in organic semiconductors, occurring at metal/alkali-halide cathodes in organic-electronic devices, is experimentally revealed and electrostatically modeled. Metal-to-organic charge transfer through the insulator, rather than doping of the organic by alkali-metal ions, is identified as the origin of the observed band-bending, which is in contrast to the localized interface dipole occurring without the insulating buffer layer.
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Affiliation(s)
- Haibo Wang
- Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489, Berlin, Germany
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46
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Shibuta M, Hirata N, Eguchi T, Nakajima A. Probing of an adsorbate-specific excited state on an organic insulating surface by two-photon photoemission spectroscopy. J Am Chem Soc 2014; 136:1825-31. [PMID: 24451024 DOI: 10.1021/ja4088456] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we investigate the photoexcited electronic states of ferrocene (Fc) molecules adsorbed on an organic insulating surface by two-photon photoemission spectroscopy. This insulating layer, composed of a decanethiolate self-assembled monolayer formed on an Au(111) substrate, enables us to probe the electronically excited states localized at the adsorbed Fc molecules. The adsorbate-specific state is resonantly excited by photons at 4.57 eV, which is 0.5 eV smaller than the energy of the first molecular Rydberg state of free Fc in the gas phase. This result indicates that the electrons are bound to both the excited hole formed in the adsorbate and the positive image charge induced in the substrate. The hybridized electronic characteristics of the adsorbate-specific state are responsible for the strong transition selectivity and short lifetime of the excited state.
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Affiliation(s)
- Masahiro Shibuta
- ERATO, Nakajima Designer Nanocluster Assembly Project, Japan Science and Technology Agency, 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012, Japan
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47
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Li Z, Chen HYT, Schouteden K, Lauwaet K, Giordano L, Trioni MI, Janssens E, Iancu V, Van Haesendonck C, Lievens P, Pacchioni G. Self-doping of ultrathin insulating films by transition metal atoms. PHYSICAL REVIEW LETTERS 2014; 112:026102. [PMID: 24484029 DOI: 10.1103/physrevlett.112.026102] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Indexed: 06/03/2023]
Abstract
Single magnetic Co atoms are deposited on atomically thin NaCl films on Au(111). Two different adsorption sites are revealed by high-resolution scanning tunneling microscopy (STM), i.e., at Na and at Cl locations. Using density functional based simulations of the STM images, we show that the Co atoms substitute with either a Na or Cl atom of the NaCl surface, resulting in cationic and anionic Co dopants with a high thermal stability. The dependence of the magnetic coupling between neighboring Co atoms on their separation is investigated via spatially resolved measurement of the local density of states.
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Affiliation(s)
- Z Li
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - H-Y T Chen
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, I-20125 Milano, Italy
| | - K Schouteden
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - K Lauwaet
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - L Giordano
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, I-20125 Milano, Italy
| | - M I Trioni
- CNR-National Research Council of Italy, ISTM, Via Golgi 19, I-20133 Milano, Italy
| | - E Janssens
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - V Iancu
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - C Van Haesendonck
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - P Lievens
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, BE-3001 Leuven, Belgium
| | - G Pacchioni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, I-20125 Milano, Italy
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48
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Chen HYT, Pacchioni G. Properties of two-dimensional insulators: a DFT study of Co adsorption on NaCl and MgO ultrathin films. Phys Chem Chem Phys 2014; 16:21838-45. [PMID: 25199958 DOI: 10.1039/c4cp03470h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interaction of TM atoms like Co with two-dimensional NaCl/Au(111) and MgO/Ag(001) ultrathin films is completely different.
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Affiliation(s)
- Hsin-Yi Tiffany Chen
- Dipartimento di Scienza dei Materiali
- Università di Milano- Bicocca
- 20125 Milano, Italy
| | - Gianfranco Pacchioni
- Dipartimento di Scienza dei Materiali
- Università di Milano- Bicocca
- 20125 Milano, Italy
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49
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Schulz F, Drost R, Hämäläinen SK, Liljeroth P. Templated self-assembly and local doping of molecules on epitaxial hexagonal boron nitride. ACS NANO 2013; 7:11121-8. [PMID: 24152095 DOI: 10.1021/nn404840h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Using low-temperature scanning tunneling microscopy, we show that monolayer hexagonal boron nitride (h-BN) on Ir(111) acts as ultrathin insulating layer for organic molecules, while simultaneously templating their self-assembly. Tunneling spectroscopy experiments on cobalt phthalocyanine (CoPC) reveal narrow molecular resonances and indicate that the charge state of CoPC is periodically modulated by the h-BN moiré superstructure. Molecules in the second layer show site-selective adsorption behavior, allowing the synthesis of molecular dimers that are spatially ordered and inaccessible by usual chemical means.
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Affiliation(s)
- Fabian Schulz
- Department of Applied Physics, Aalto University School of Science , P.O. Box 15100, 00076 Aalto, Finland
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50
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Scivetti I, Persson M. The electrostatic interaction of an external charged system with a metal surface: a simplified density functional theory approach. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:355006. [PMID: 23896868 DOI: 10.1088/0953-8984/25/35/355006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
As a first step to meet the challenge to calculate the electronic structure and total energy of charged states of atoms and molecules adsorbed on ultrathin insulating films supported by a metallic substrate using density functional theory (DFT), we have developed a simplified new DFT scheme that only describes the electrostatic interaction of an external charged system with a metal surface. This purely electrostatic interaction is obtained from the assumption that the electron densities of the two fragments (charged system and metal surface) are non-overlapping and by neglecting non-local exchange-correlation effects such as the van der Waals interactions between the two fragments. In addition, the response of the metal surface to the electrostatic potential from the charged system is treated to linear order, whereas the charged system is treated fully within DFT. In particular, we consider the classical perfect conductor model for the metal response, although our formalism is not limited to this approximation. To test the computational implementation of this new scheme, we have considered the case of a Na(+) cation interacting with a perfect conductor. The application of this new methodology to realistic problems involving charged systems adsorbed on insulating films supported by a metal surface are deferred to a separate following publication.
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Affiliation(s)
- Iván Scivetti
- Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool L69 3BX, UK.
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