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Freeman M, Applestone R, Behn W, Brar V. Haptic sensation-based scanning probe microscopy: Exploring perceived forces for optimal intuition-driven control. Ultramicroscopy 2024; 255:113856. [PMID: 37783064 DOI: 10.1016/j.ultramic.2023.113856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 07/10/2023] [Accepted: 09/14/2023] [Indexed: 10/04/2023]
Abstract
We demonstrate a cryogenic scanning probe microscope (SPM) that has been modified to be controlled with a haptic device, such that the operator can 'feel' the surface of a sample under investigation. This system allows for direct tactile sensation of the atoms in and on top of a crystal, and allows the operator to perceive, by using different SPM modalities, sensations that are representative of the relevant atomic forces and tunneling processes controlling the SPM. In particular, we operate the microscope in modes of (1) conventional STM feedback, (2) energy-dependent electron density imaging, (3) q-plus AFM frequency shift based force sensing, and (4) atomic manipulation/sliding. We also use software to modify the haptic feedback sensation to mimic different interatomic forces, including covalent bonding, Coulomb repulsion, Van der Waals repulsion and a full Lennard-Jones potential. This manner of SPM control creates new opportunities for human-based intuition scanning, and also acts as a novel educational tool to aid in understanding materials at an atomic level.
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Affiliation(s)
- M Freeman
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - R Applestone
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - W Behn
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - V Brar
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States.
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2
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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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3
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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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Hazan Z, Averbukh M, Manassen Y. ESR-STM on diamagnetic molecule: C 60 on graphene. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 348:107377. [PMID: 36709618 DOI: 10.1016/j.jmr.2023.107377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 06/18/2023]
Abstract
Electron Spin Resonance-Scanning Tunneling Microscopy (ESR-STM) of C60 radical ion on graphene is a first demonstration of ESR-STM on diamagnetic molecules. ESR-STM signal at gaverage=2.0±0.1 was measured in accordance with macroscopic ESR of C60 radical ion. The ESR-STM signal was bias voltage dependent, as it reflects the charge state of the molecule. The signal appears in the bias voltage which enables the ionization of the lowest unoccupied molecular orbital (LUMO) - creation of radical anion, and the highest occupied molecular orbital (HOMO) - creation of a radical cation of the C60 molecule when it deposited on graphene. In parallel, ESR-STM signal at gaverage=1.7±0.1 was ascribed to Tungsten oxide (WO3) at the tip apex. In several experiments, triplet spectrum was observed, and we ascribed their origin to zero-field splitting of doubly ionized C120O-2 dimer, as argued in previous ESR experiments of C60 samples. Second possibility is hyperfine coupling with two 13C nuclei. In addition, we further validate the interference mechanism previously suggested for ESR-STM noise spectroscopy. The ability of ESR-STM to observe ESR of diamagnetic molecules in parallel with observing their electronic structure, provides a general single molecule identification technique.
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Affiliation(s)
- Zion Hazan
- Department of Physics, Ben Gurion University, P.O. Box 653, Beer Sheva 84105, Israel
| | - Michael Averbukh
- Department of Physics, Ben Gurion University, P.O. Box 653, Beer Sheva 84105, Israel
| | - Yishay Manassen
- Department of Physics, Ben Gurion University, P.O. Box 653, Beer Sheva 84105, Israel.
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5
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Benhnia A, Watanabe S, Tuerhong R, Nakaya M, Onoe J, Bucher JP. Resolving Site-Specific Energy Levels of Small-Molecule Donor-Acceptor Heterostructures Close to Metal Contacts. NANOMATERIALS 2021; 11:nano11061618. [PMID: 34203037 PMCID: PMC8234413 DOI: 10.3390/nano11061618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 11/16/2022]
Abstract
The active material of optoelectronic devices must accommodate for contacts which serve to collect or inject the charge carriers. It is the purpose of this work to find out to which extent properties of organic optoelectronic layers change close to metal contacts compared to known properties of bulk materials. Bottom-up fabrication capabilities of model interfaces under ultrahigh vacuum and single-atom low temperature (LT)-STM spectroscopy with density functional theory (DFT) calculations are used to detect the spatial modifications of electronic states such as frontier-orbitals at interfaces. The system under consideration is made of a silver substrate covered with a blend of C60 and ZnPc molecules of a few monolayers. When C60 and ZnPc are separately adsorbed on Ag(111), they show distinct spectroscopic features in STM. However, when C60 is added to the ZnPc monolayer, it shows scanning tunneling spectra similar to ZnPc, revealing a strong interaction of C60 with the ZnPc induced by the substrate. DFT calculations on a model complex confirm the strong hybridization of C60 with ZnPc layer upon adsorption on Ag(111), thus highlighting the role of boundary layers where the donor-acceptor character is strongly perturbed. The calculation also reveals a significant charge transfer from the Ag to the complex that is likely responsible for a downward shift of the molecular LUMO in agreement with the experiment.
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Affiliation(s)
- Amani Benhnia
- Institutde Physiqueet Chimiedes Matériaux de Strasbourg (IPCMS), Université de Strasbourg, CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France; (A.B.); (R.T.)
| | - Shinta Watanabe
- Department of Energy Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan; (S.W.); (M.N.); (J.O.)
| | - Rouzhaji Tuerhong
- Institutde Physiqueet Chimiedes Matériaux de Strasbourg (IPCMS), Université de Strasbourg, CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France; (A.B.); (R.T.)
| | - Masato Nakaya
- Department of Energy Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan; (S.W.); (M.N.); (J.O.)
| | - Jun Onoe
- Department of Energy Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan; (S.W.); (M.N.); (J.O.)
| | - Jean-Pierre Bucher
- Institutde Physiqueet Chimiedes Matériaux de Strasbourg (IPCMS), Université de Strasbourg, CNRS, IPCMS UMR 7504, F-67034 Strasbourg, France; (A.B.); (R.T.)
- Correspondence:
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Guo H, Martínez-Galera AJ, Gómez-Rodríguez JM. C 60 self-orientation on hexagonal boron nitride induced by intermolecular coupling. NANOTECHNOLOGY 2020; 32:025711. [PMID: 33073772 DOI: 10.1088/1361-6528/abbbb2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A deep grasp of the properties of the interface between organic molecules and hexagonal boron nitride (h-BN) is essential for the full implementation of these two building blocks in the next generation of electronic devices. Here, using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), we report on the geometric and electronic features of C60 evaporated on a single layer of h-BN grown on a Rh(110) surface under ultra-high vacuum. Two different molecular assemblies of C60 on the h-BN/Rh(110) surface were observed. The first STM study at room temperature (RT) and at low temperatures (40 K) looked at the molecular orientation of C60 on a two-dimensional layered material. Intramolecular-resolution images demonstrate the existence of a phase transition of C60 over the h-BN/Rh(110) surface similar to that found on bulk solid C60. At RT molecules exhibit random orientations, while at 40 K such rotational disorder vanishes and they adopt a common orientation over the h-BN/Rh(110) surface. The decrease in thermal energy allows recognition between C60 molecules, and they become equally oriented in the configuration at which the van der Waals intermolecular interactions are optimized. Bias-dependent submolecular features obtained by means of high-resolution STM images are interpreted as the highest occupied and lowest unoccupied molecular orbitals. STS data showed that fullerenes are electronically decoupled from the substrate, with a negligible charge transfer effect if any. Finally, the very early stages of multilayer growth were also investigated.
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Affiliation(s)
- Haojie Guo
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049, Spain
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Castillo-Chará J. Density functional calculation of the molecular properties of the [Au20-C60-Au20]− (n = 0, 1, 2, 3) model complexes. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Shang Y, Wang Z, Yang D, Wang Y, Ma C, Tao M, Sun K, Yang J, Wang J. Orientation Ordering and Chiral Superstructures in Fullerene Monolayer on Cd (0001). NANOMATERIALS 2020; 10:nano10071305. [PMID: 32635309 PMCID: PMC7407170 DOI: 10.3390/nano10071305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/21/2020] [Accepted: 06/30/2020] [Indexed: 12/11/2022]
Abstract
The structure of C60 thin films grown on Cd (0001) surface has been investigated from submonolayer to second monolayer regimes with a low-temperature scanning tunneling microscopy (STM). There are different C60 domains with various misorientation angles relative to the lattice directions of Cd (0001). In the (2√3 × 2√3) R30° domain, orientational disorder of the individual C60 molecules with either pentagon, hexagon, or 6:6 bond facing up has been observed. However, orientation ordering appeared in the R26° domain such that all the C60 molecules adopt the same orientation with the 6:6 bond facing up. In particular, complex chiral motifs composed of seven C60 molecules with clockwise or anticlockwise handedness have been observed in the R4° and R8° domains, respectively. Scanning tunneling spectroscopy (STS) measurements reveal a reduced HOMO–LOMO gap of 2.1 eV for the C60 molecules adsorbed on Cd (0001) due to the substrate screening and charge transfer from Cd to C60 molecules.
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Lin CL, Kawakami N, Arafune R, Minamitani E, Takagi N. Scanning tunneling spectroscopy studies of topological materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:243001. [PMID: 32069440 DOI: 10.1088/1361-648x/ab777d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Topological materials have become promising materials for next-generation devices by utilizing their exotic electronic states. Their exotic states caused by spin-orbital coupling usually locate on the surfaces or at the edges. Scanning tunneling spectroscopy (STS) is a powerful tool to reveal the local electronic structures of condensed matters. Therefore, STS provides us with an almost perfect method to access the exotic states of topological materials. In this topical review, we report the current investigations by several methods based on the STS technique for layered topological material from transition metal dichalcogenide Weyl semimetals (WTe2 and MoTe2) to two dimensional topological insulators (layered bismuth and silicene). The electronic characteristics of these layered topological materials are experimentally identified.
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Affiliation(s)
- Chun-Liang Lin
- Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan, Republic of China
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10
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Perroni CA, Cataudella V. On the Role of Local Many-Body Interactions on the Thermoelectric Properties of Fullerene Junctions. ENTROPY 2019; 21:e21080754. [PMID: 33267468 PMCID: PMC7515282 DOI: 10.3390/e21080754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/23/2019] [Accepted: 07/31/2019] [Indexed: 11/16/2022]
Abstract
The role of local electron–vibration and electron–electron interactions on the thermoelectric properties of molecular junctions is theoretically analyzed focusing on devices based on fullerene molecules. A self-consistent adiabatic approach is used in order to obtain a non-perturbative treatment of the electron coupling to low frequency vibrational modes, such as those of the molecule center of mass between metallic leads. The approach also incorporates the effects of strong electron–electron interactions between molecular degrees of freedom within the Coulomb blockade regime. The analysis is based on a one-level model which takes into account the relevant transport level of fullerene and its alignment to the chemical potential of the leads. We demonstrate that only the combined effect of local electron–vibration and electron–electron interactions is able to predict the correct behavior of both the charge conductance and the Seebeck coefficient in very good agreement with available experimental data.
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11
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Park M, Kang DG, Yoon WJ, Choi YJ, Koo J, Lim SI, Jeong KU. Programmed Hierarchical Hybrid Nanostructures from Fullerene-Dendrons and Pyrene-Dendrons. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1803291. [PMID: 30303613 DOI: 10.1002/smll.201803291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/14/2018] [Indexed: 06/08/2023]
Abstract
The construction of fullerene (C60 ) hierarchical nanostructures with the help of amphiphilic molecules remains a challenging task in nanoscience and nanotechnology. Utilizing the host-guest complex concept, sub-10 nm layered superstructures are constructed from a monofunctionalized C60 dendron (C60 D, guest) and tweezer-like pyrene dendron (PD, host). Since C60 D and PD are asymmetric shape amphiphiles having liquid crystal (LC) dendrons, both C60 D and PD construct head-to-head bilayer superstructures by themselves. From fluorescence titration experiments, it is realized that the host-guest complex shows 1:1 stoichiometric binding with a binding constant (Ksv = 2.45 × 105 m-1 ). Based on the morphological observations and scattering analyses, it is found that buckle-like asymmetric building blocks (C60 D·PD) are self-assembled by the host-guest complex and construct multilayer hybrid nanostructures. The hierarchical hybrid nanostructures consist of the self-assembled C60 D·PD bilayer with a 2D C60 ·P nanoarray sandwiched between LC dendrons. This advanced strategy is expected to be a practicable and rational guideline for the fabrication of programmed hierarchical hybrid nanostructures.
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Affiliation(s)
- Minwook Park
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
| | - Dong-Gue Kang
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
| | - Won-Jin Yoon
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
| | - Yu-Jin Choi
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
| | - Jahyeon Koo
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
| | - Seok-In Lim
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
| | - Kwang-Un Jeong
- BK21 Plus Haptic Polymer Composite Research Team and Department of Polymer-Nano Science and Technology Chonbuk National University, Jeonju, 54896, South Korea
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12
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Kröger J, Doppagne B, Scheurer F, Schull G. Fano Description of Single-Hydrocarbon Fluorescence Excited by a Scanning Tunneling Microscope. NANO LETTERS 2018; 18:3407-3413. [PMID: 29719154 DOI: 10.1021/acs.nanolett.8b00304] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The detection of fluorescence with submolecular resolution enables the exploration of spatially varying photon yields and vibronic properties at the single-molecule level. By placing individual polycyclic aromatic hydrocarbon molecules into the plasmon cavity formed by the tip of a scanning tunneling microscope and a NaCl-covered Ag(111) surface, molecular light emission spectra are obtained that unravel vibrational progression. In addition, light spectra unveil a signature of the molecule even when the tunneling current is injected well separated from the molecular emitter. This signature exhibits a distance-dependent Fano profile that reflects the subtle interplay between inelastic tunneling electrons, the molecular exciton and localized plasmons in at-distance as well as on-molecule fluorescence. The presented findings open the path to luminescence of a different class of molecules than investigated before and contribute to the understanding of single-molecule luminescence at surfaces in a unified picture.
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Affiliation(s)
- Jörg Kröger
- Institut de Physique et Chimie des Matériaux de Strasbourg , Université de Strasbourg, CNRS, IPCMS, UMR 7504 , F-67000 Strasbourg , France
| | - Benjamin Doppagne
- Institut de Physique et Chimie des Matériaux de Strasbourg , Université de Strasbourg, CNRS, IPCMS, UMR 7504 , F-67000 Strasbourg , France
| | - Fabrice Scheurer
- Institut de Physique et Chimie des Matériaux de Strasbourg , Université de Strasbourg, CNRS, IPCMS, UMR 7504 , F-67000 Strasbourg , France
| | - Guillaume Schull
- Institut de Physique et Chimie des Matériaux de Strasbourg , Université de Strasbourg, CNRS, IPCMS, UMR 7504 , F-67000 Strasbourg , France
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13
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Jena P, Sun Q. Super Atomic Clusters: Design Rules and Potential for Building Blocks of Materials. Chem Rev 2018; 118:5755-5870. [DOI: 10.1021/acs.chemrev.7b00524] [Citation(s) in RCA: 302] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Puru Jena
- Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
| | - Qiang Sun
- Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000, United States
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14
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Luft M, Groß B, Schulz M, Lützen A, Schiek M, Nilius N. Adsorption of squaraine molecules to Au(111) and Ag(001) surfaces. J Chem Phys 2018; 148:074702. [DOI: 10.1063/1.5017826] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Maike Luft
- Carl von Ossietzky Universität, Institut für Physik, D-26111 Oldenburg, Germany
| | - Boris Groß
- Carl von Ossietzky Universität, Institut für Physik, D-26111 Oldenburg, Germany
| | - Matthias Schulz
- University of Bonn, Kekulé Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany
| | - Arne Lützen
- University of Bonn, Kekulé Institute of Organic Chemistry and Biochemistry, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany
| | - Manuela Schiek
- Carl von Ossietzky Universität, Institut für Physik, D-26111 Oldenburg, Germany
| | - Niklas Nilius
- Carl von Ossietzky Universität, Institut für Physik, D-26111 Oldenburg, Germany
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15
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Kuhnke K, Große C, Merino P, Kern K. Atomic-Scale Imaging and Spectroscopy of Electroluminescence at Molecular Interfaces. Chem Rev 2017; 117:5174-5222. [DOI: 10.1021/acs.chemrev.6b00645] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Klaus Kuhnke
- Max-Planck-Institut für Festkörperforschung, Stuttgart 70569, Germany
| | - Christoph Große
- Max-Planck-Institut für Festkörperforschung, Stuttgart 70569, Germany
| | - Pablo Merino
- Max-Planck-Institut für Festkörperforschung, Stuttgart 70569, Germany
| | - Klaus Kern
- Max-Planck-Institut für Festkörperforschung, Stuttgart 70569, Germany
- Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
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16
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Zhou CS, Shan H, Li B, Zhao AD. Imaging Molecular Orbitals of Single Picene Molecules Adsorbed on Cu(111) Surface: a Combined Experimental and Theoretical Study. CHINESE J CHEM PHYS 2017. [DOI: 10.1063/1674-0068/30/cjcp1606123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Chun-sheng Zhou
- 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 230026, China
- Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - Huan Shan
- 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 230026, China
| | - Bin Li
- 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 230026, China
| | - Ai-di Zhao
- 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 230026, China
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17
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Rauschenbach S, Ternes M, Harnau L, Kern K. Mass Spectrometry as a Preparative Tool for the Surface Science of Large Molecules. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2016; 9:473-98. [PMID: 27089378 DOI: 10.1146/annurev-anchem-071015-041633] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Measuring and understanding the complexity that arises when nanostructures interact with their environment are one of the major current challenges of nanoscale science and technology. High-resolution microscopy methods such as scanning probe microscopy have the capacity to investigate nanoscale systems with ultimate precision, for which, however, atomic scale precise preparation methods of surface science are a necessity. Preparative mass spectrometry (pMS), defined as the controlled deposition of m/z filtered ion beams, with soft ionization sources links the world of large, biological molecules and surface science, enabling atomic scale chemical control of molecular deposition in ultrahigh vacuum (UHV). Here we explore the application of high-resolution scanning probe microscopy and spectroscopy to the characterization of structure and properties of large molecules. We introduce the fundamental principles of the combined experiments electrospray ion beam deposition and scanning tunneling microscopy. Examples for the deposition and investigation of single particles, for layer and film growth, and for the investigation of electronic properties of individual nonvolatile molecules show that state-of-the-art pMS technology provides a platform analog to thermal evaporation in conventional molecular beam epitaxy. Additionally, it offers additional, unique features due to the use of charged polyatomic particles. This new field is an enormous sandbox for novel molecular materials research and demands the development of advanced molecular ion beam technology.
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Affiliation(s)
| | - Markus Ternes
- Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany;
| | | | - Klaus Kern
- Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany;
- Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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18
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Zhang Y, Luo Y, Zhang Y, Yu YJ, Kuang YM, Zhang L, Meng QS, Luo Y, Yang JL, Dong ZC, Hou JG. Visualizing coherent intermolecular dipole–dipole coupling in real space. Nature 2016; 531:623-7. [DOI: 10.1038/nature17428] [Citation(s) in RCA: 223] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 02/11/2016] [Indexed: 12/29/2022]
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Nocera A, Perroni CA, Ramaglia VM, Cataudella V. Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:439-64. [PMID: 27335736 PMCID: PMC4901550 DOI: 10.3762/bjnano.7.39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 02/08/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Soft nanosystems are electronic nanodevices, such as suspended carbon nanotubes or molecular junctions, whose transport properties are modulated by soft internal degrees of freedom, for example slow vibrational modes. Effects of the electron-vibration coupling on the charge and heat transport of soft nanoscopic systems are theoretically investigated in the presence of time-dependent perturbations, such as a forcing antenna or pumping terms between the leads and the nanosystem. A well-established approach valid for non-equilibrium adiabatic regimes is generalized to the case where external time-dependent perturbations are present. Then, a number of relevant applications of the method are reviewed for systems composed by a quantum dot (or molecule) described by a single electronic level coupled to a vibrational mode. RESULTS Before introducing time-dependent perturbations, the range of validity of the adiabatic approach is discussed showing that a very good agreement with the results of an exact quantum calculation is obtained in the limit of low level occupation. Then, we show that the interplay between the low frequency vibrational modes and the electronic degrees of freedom affects the thermoelectric properties within the linear response regime finding out that the phonon thermal conductance provides an important contribution to the figure of merit at room temperature. Our work has been stimulated by recent experimental results on carbon nanotube electromechanical devices working in the semiclassical regime (resonator frequencies in the megahertz range compared to an electronic hopping frequency of the order of tens of gigahertz) with extremely high quality factors. The nonlinear vibrational regime induced by the external antenna in such systems has been discussed within the non-perturbative adiabatic approach reproducing quantitatively the characteristic asymmetric shape of the current-frequency curves. Within the same set-up, we have proved that the antenna is able to pump sufficient charge close to the mechanical resonance making single-parameter adiabatic charge pumping feasible in carbon nanotube resonators. The pumping mechanism that we observe is different from that acting in the two parameter pumping and, instead, it is based on an important dynamic adjustment of the mechanical motion of the nanotube to the external drive in the weakly nonlinear regime. Finally, stochastic forces induced by quantum and thermal fluctuations due to the electron charging of the quantum dot are shown to affect in a significant way a Thouless charge pump realized with an elastically deformable quantum dot. In this case, the pumping mechanism is also shown to be magnified when the frequency of the external drive is resonant with the proper frequency of the deformable quantum dot. In this regime, the pumping current is not strongly reduced by the temperature, giving a measurable effect. CONCLUSION Aim of this review has been to discuss common features of different soft nanosystems under external drive. The most interesting effects induced by time-dependent perturbations are obtained when the external forcing is nearly resonant with the slow vibrational modes. Indeed, not only the external forcing can enhance the electronic response, but it also induces nonlinear regimes where the interplay between electronic and vibrational degrees of freedom plays a major role.
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Affiliation(s)
- Alberto Nocera
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Carmine Antonio Perroni
- CNR-SPIN and Department of Physics “Ettore Pancini”, Universita’ degli Studi di Napoli Federico II, Complesso Universitario Monte Sant’Angelo, Via Cintia, I-80126 Napoli, Italy
| | - Vincenzo Marigliano Ramaglia
- CNR-SPIN and Department of Physics “Ettore Pancini”, Universita’ degli Studi di Napoli Federico II, Complesso Universitario Monte Sant’Angelo, Via Cintia, I-80126 Napoli, Italy
| | - Vittorio Cataudella
- CNR-SPIN and Department of Physics “Ettore Pancini”, Universita’ degli Studi di Napoli Federico II, Complesso Universitario Monte Sant’Angelo, Via Cintia, I-80126 Napoli, Italy
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20
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Große C, Gunnarsson O, Merino P, Kuhnke K, Kern K. Nanoscale Imaging of Charge Carrier and Exciton Trapping at Structural Defects in Organic Semiconductors. NANO LETTERS 2016; 16:2084-2089. [PMID: 26871739 DOI: 10.1021/acs.nanolett.6b00190] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Charge carrier and exciton trapping in organic semiconductors crucially determine the performance of organic (opto-)electronic devices such as organic field-effect transistors, light-emitting diodes, or solar cells. However, the microscopic origin of the relevant traps generally remains unclear, as most spectroscopic techniques are unable to simultaneously probe the electronic and morphological structure of individual traps. Here, we employ low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) as well as tight-binding calculations derived from ab initio calculations to image the localized electronic states arising at structural defects in thin C60 films (<10 ML). The spatially and spectrally resolved STM-induced luminescence at these states reveals an enhanced radiative decay of excitons, which is interpreted in terms of the local symmetry lowering and the trapping of excitons by an X-trap. The combined mapping of the STM-induced luminescence, electronic structure, and morphology thus provides new insights into the origin and characteristics of individual exciton traps in organic semiconductors and offers new avenues to study charge carrier and exciton dynamics on molecular scales.
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Affiliation(s)
- Christoph Große
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Olle Gunnarsson
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Pablo Merino
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Klaus Kuhnke
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
- École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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21
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Zhang Y, Zhang Y, Li G, Lu J, Lin X, Tan Y, Feng X, Du S, Müllen K, Gao HJ. Construction of single-crystalline supramolecular networks of perchlorinated hexa-peri-hexabenzocoronene on Au(111). J Chem Phys 2015; 142:101911. [DOI: 10.1063/1.4907369] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yi Zhang
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Yanfang Zhang
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Geng Li
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Jianchen Lu
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiao Lin
- University of Chinese Academy of Sciences and Institute of Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanzhi Tan
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xinliang Feng
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Shixuan Du
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Klaus Müllen
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Hong-Jun Gao
- Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
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22
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Ewen PR, Sanning J, Koch T, Doltsinis NL, Strassert CA, Wegner D. Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes - a new strategy for OLED materials. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:2248-2258. [PMID: 25551053 PMCID: PMC4273280 DOI: 10.3762/bjnano.5.234] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 10/24/2014] [Indexed: 05/30/2023]
Abstract
The improvement of molecular electronic devices such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS) are powerful tools to correlate the electronic properties of phosphorescent complexes (i.e., triplet emitters) with their molecular structure as well as the local environment around a single molecule. We used spectroscopic mapping to visualize several occupied and unoccupied molecular frontier orbitals of Pt(II) complexes adsorbed on Au(111). The analysis showed that the molecules exhibit a peculiar localized strong hybridization that leads to partial depopulation of a dz² orbital, while the ligand orbitals are almost unchanged. We further found that substitution of functional groups at well-defined positions can alter specific molecular orbitals without influencing the others. The results open a path toward the tailored design of electronic and optical properties of triplet emitters by smart ligand substitution, which may improve the performance of future OLED devices.
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Affiliation(s)
- Pascal R Ewen
- Institut for Molecules and Materials, Radboud Universiteit Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
| | - Jan Sanning
- Physikalisches Institut, Westfälische Wilhelms Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Tobias Koch
- Institut für Festkörpertheorie and Center for Multiscale Theory and Computation, Westfälische Wilhelms Universität Münster, Wilhem-Klemm-Straße 10 and Corrensstraße 40, 48149 Münster, Germany
| | - Nikos L Doltsinis
- Institut für Festkörpertheorie and Center for Multiscale Theory and Computation, Westfälische Wilhelms Universität Münster, Wilhem-Klemm-Straße 10 and Corrensstraße 40, 48149 Münster, Germany
| | - Cristian A Strassert
- Physikalisches Institut, Westfälische Wilhelms Universität Münster, Wilhelm-Klemm-Straße 10, 48149 Münster, Germany
| | - Daniel Wegner
- Institut for Molecules and Materials, Radboud Universiteit Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
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23
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Yang Z, Corso M, Robles R, Lotze C, Fitzner R, Mena-Osteritz E, Bäuerle P, Franke KJ, Pascual JI. Orbital redistribution in molecular nanostructures mediated by metal-organic bonds. ACS NANO 2014; 8:10715-10722. [PMID: 25244124 DOI: 10.1021/nn504431e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Dicyanovinyl-quinquethiophene (DCV5T-Me2) is a prototype conjugated oligomer for highly efficient organic solar cells. This class of oligothiophenes are built up by an electron-rich donor (D) backbone and terminal electron-deficient acceptor (A) moieties. Here, we investigated its structural and electronic properties when it is adsorbed on a Au(111) surface using low temperature scanning tunneling microscopy/spectroscopy (STM/STS) and atomic force microscopy (AFM). We find that DCV5T-Me2 self-assembles in extended chains, stabilized by intercalated Au atoms. The effect of metal-ligand hybridization with Au adatoms causes an energetic downshift of the DCV5T-Me2 lowest unoccupied molecular orbital (LUMO) with respect to the uncoordinated molecules on the surface. The asymmetric coordination of a gold atom to only one molecular end group leads to an asymmetric localization of the LUMO and LUMO+1 states at opposite sides. Using model density functional theory (DFT) calculations, we explain such orbital reshaping as a consequence of linear combinations of the original LUMO and LUMO+1 orbitals, mixed by the attachment of a bridging Au adatom. Our study shows that the alignment of molecular orbitals and their distribution within individual molecules can be modified by contacting them to metal atoms in specific sites.
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Affiliation(s)
- Zechao Yang
- Institut für Experimentalphysik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
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24
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Jung M, Shin D, Sohn SD, Kwon SY, Park N, Shin HJ. Atomically resolved orientational ordering of C60 molecules on epitaxial graphene on Cu(111). NANOSCALE 2014; 6:11835-11840. [PMID: 25169153 DOI: 10.1039/c4nr03249g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A detailed understanding of interactions between molecules and graphene is one of the key issues for tailoring the properties of graphene-based molecular devices, because the electronic and structural properties of molecular layers on surfaces are determined by intermolecular and molecule-substrate interactions. Here, we present the atomically resolved experimental measurements of the self-assembled fullerene molecules on single-layer graphene on Cu(111). Fullerene molecules form a (4 × 4) superstructure on graphene/Cu(111), revealing only single molecular orientation. We can resolve the exact adsorption site and the configuration of fullerene by means of low-temperature scanning tunnelling microscopy (LT-STM) and density functional theory (DFT) calculations. The adsorption orientation can be explained in terms of the competition between intermolecular interactions and molecule-substrate interactions, where strong Coulomb interactions among the fullerenes determine the in-plane orientation of the fullerene. Our results provide important implications for developing carbon-based organic devices using a graphene template in the future.
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Affiliation(s)
- Minbok Jung
- School of Materials Science and Engineering, Center for Multidimensional Carbon Materials and Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 689-798, Republic of Korea.
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25
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Pinardi AL, Biddau G, van De Ruit K, Otero-Irurueta G, Gardonio S, Lizzit S, Schennach R, Flipse CFJ, López MF, Méndez J, Pérez R, Martín-Gago JA. Vacancy formation on C60/Pt (111): unraveling the complex atomistic mechanism. NANOTECHNOLOGY 2014; 25:385602. [PMID: 25180864 DOI: 10.1088/0957-4484/25/38/385602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The interaction of fullerenes with transition metal surfaces leads to the development of an atomic network of ordered vacancies on the metal. However, the structure and formation mechanism of this intricate surface reconstruction is not yet understood at an atomic level. We combine scanning tunneling microscopy, high resolution and temperature programmed-x-ray photoelectrons spectroscopy, and density functional theory calculations to show that the vacancy formation in C60/Pt(111) is a complex process in which fullerenes undergo two significant structural rearrangements upon thermal annealing. At first, the molecules are physisorbed on the surface; next, they chemisorb inducing the formation of an adatom-vacancy pair on the side of the fullerene. Finally, this metastable state relaxes when the adatom migrates away and the vacancy moves under the molecule. The evolution from a weakly-bound fullerene to a chemisorbed state with a vacancy underneath could be triggered by residual H atoms on the surface which prevent a strong surface-adsorbate bonding right after deposition. Upon annealing at about 440 K, when all H has desorbed, the C60 interacts with the Pt surface atoms forming the vacancy-adatom pair. This metastable state induces a small charge transfer and precedes the final adsorption structure.
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Affiliation(s)
- Anna L Pinardi
- ESISNA Group Instituto de Ciencia de Materiales de Madrid (CSIC), c/ Sor Juana Inés de la Cruz, E-28049 Madrid, Spain
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26
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Géranton G, Seiler C, Bagrets A, Venkataraman L, Evers F. Transport properties of individual C60-molecules. J Chem Phys 2014; 139:234701. [PMID: 24359380 DOI: 10.1063/1.4840535] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Electrical and thermal transport properties of C60 molecules are investigated with density-functional-theory based calculations. These calculations suggest that the optimum contact geometry for an electrode terminated with a single-Au atom is through binding to one or two C-atoms of C60 with a tendency to promote the sp(2)-hybridization into an sp(3)-type one. Transport in these junctions is primarily through an unoccupied molecular orbital that is partly hybridized with the Au, which results in splitting the degeneracy of the lowest unoccupied molecular orbital triplet. The transmission through these junctions, however, cannot be modeled by a single Lorentzian resonance, as our results show evidence of quantum interference between an occupied and an unoccupied orbital. The interference results in a suppression of conductance around the Fermi energy. Our numerical findings are readily analyzed analytically within a simple two-level model.
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Affiliation(s)
- G Géranton
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| | - C Seiler
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| | - A Bagrets
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
| | - L Venkataraman
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
| | - F Evers
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Campus North, D-76128 Karlsruhe, Germany
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27
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Li G, Huang L, Xu W, Que Y, Zhang Y, Lu J, Du S, Liu Y, Gao HJ. Constructing molecular structures on periodic superstructure of graphene/Ru(0001). PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:20130015. [PMID: 24615151 PMCID: PMC3949362 DOI: 10.1098/rsta.2013.0015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We review the way to fabricate large-scale, high-quality and single crystalline graphene epitaxially grown on Ru(0001) substrate. A moiré pattern of the graphene/Ru(0001) is formed due to the lattice mismatch between graphene and Ru(0001). This superstructure gives rise to surface charge redistribution and could behave as an ordered quantum dot array, which results in a perfect template to guide the assembly of organic molecular structures. Molecules, for example iron phthalocyanine and C60, on this template show how the molecule-substrate interaction makes different superstructures. These results show the possibility of constructing ordered molecular structures on graphene/Ru(0001), which is helpful for practical applications in the future.
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Affiliation(s)
- Geng Li
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Li Huang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Wenyan Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yande Que
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yi Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Jianchen Lu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Shixuan Du
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yunqi Liu
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Hong-Jun Gao
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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Abstract
Vibrational modes of molecules are fundamental properties determined by intramolecular bonding, atomic masses, and molecular geometry, and often serve as important channels for dissipation in nanoscale processes. Although single-molecule junctions have been used to manipulate electronic structure and related functional properties of molecules, electrical control of vibrational mode energies has remained elusive. Here we use simultaneous transport and surface-enhanced Raman spectroscopy measurements to demonstrate large, reversible, voltage-driven shifts of vibrational mode energies of C60 molecules in gold junctions. C60 mode energies are found to vary approximately quadratically with bias, but in a manner inconsistent with a simple vibrational Stark effect. Our theoretical model instead suggests that the mode shifts are a signature of bias-driven addition of electronic charge to the molecule. These results imply that voltage-controlled tuning of vibrational modes is a general phenomenon at metal-molecule interfaces and is a means of achieving significant shifts in vibrational energies relative to a pure Stark effect.
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29
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Sun L, Diaz-Fernandez YA, Gschneidtner TA, Westerlund F, Lara-Avila S, Moth-Poulsen K. Single-molecule electronics: from chemical design to functional devices. Chem Soc Rev 2014; 43:7378-411. [DOI: 10.1039/c4cs00143e] [Citation(s) in RCA: 361] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The use of single molecules in electronics represents the next limit of miniaturisation of electronic devices, which would enable to continue the trend of aggressive downscaling of silicon-based electronic devices.
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Affiliation(s)
- Lanlan Sun
- Department of Chemical and Biological Engineering
- Chalmers University of Technology
- , Sweden
| | - Yuri A. Diaz-Fernandez
- Department of Chemical and Biological Engineering
- Chalmers University of Technology
- , Sweden
| | - Tina A. Gschneidtner
- Department of Chemical and Biological Engineering
- Chalmers University of Technology
- , Sweden
| | - Fredrik Westerlund
- Department of Chemical and Biological Engineering
- Chalmers University of Technology
- , Sweden
| | - Samuel Lara-Avila
- Department of Micro and Nanotechnology
- MC2
- Chalmers University of Technology
- , Sweden
| | - Kasper Moth-Poulsen
- Department of Chemical and Biological Engineering
- Chalmers University of Technology
- , Sweden
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30
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Ewen PR, Sanning J, Doltsinis NL, Mauro M, Strassert CA, Wegner D. Unraveling orbital hybridization of triplet emitters at the metal-organic interface. PHYSICAL REVIEW LETTERS 2013; 111:267401. [PMID: 24483812 DOI: 10.1103/physrevlett.111.267401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Indexed: 05/11/2023]
Abstract
We have investigated the structural and electronic properties of phosphorescent planar platinum(II) complexes at the interface of Au(111) with submolecular resolution using combined scanning tunneling microscopy and spectroscopy as well as density functional theory. Our analysis shows that molecule-substrate coupling and lateral intermolecular interactions are weak. While the ligand orbitals remain essentially unchanged upon contact with the substrate, we found modified electronic behavior at the Pt atom due to local hybridization and charge transfer to the substrate. Thus, this novel class of phosphorescent molecules exhibits well-defined and tunable interaction with its local environment.
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Affiliation(s)
- Pascal R Ewen
- Physikalisches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Jan Sanning
- Physikalisches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Nikos L Doltsinis
- Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Matteo Mauro
- Laboratoire de Chimie et des Biomatériaux Supramoléculaires, Institut de Science et d'Ingénierie Supramoléculaires (ISIS), Université de Strasbourg, 67083 Strasbourg, France
| | - Cristian A Strassert
- Physikalisches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
| | - Daniel Wegner
- Physikalisches Institut and Center for Nanotechnology (CeNTech), Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
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31
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Zhu G, Li Y, Lü K, Sun Q. Phthalocyanine-based organometallic nanocages: properties and gas storage. Chemphyschem 2013; 15:126-31. [PMID: 24288296 DOI: 10.1002/cphc.201300830] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Indexed: 11/09/2022]
Abstract
Phthalocyanine (Pc) molecules are well-known flexible structural units for 1D nanotubes and 2D nanosheets. First-principles calculations combined with grand canonical Monte Carlo simulations are used to obtain the geometries, electronic structures, optical properties, and hydrogen-storage capacities of nanocages consisting of six Pc molecules with six Mg or Ca atoms. The primitive Pc cage has Th symmetry with twofold degeneracy in the highest occupied molecular orbital (HOMO), and threefold degeneracy in the lowest unoccupied molecular orbital (LUMO); the corresponding HOMO-LUMO gap is found to be 0.97 eV. The MgPc and CaPc cages have Oh symmetry with a HOMO-LUMO gap of 1.24 and 1.13 eV, respectively. Optical absorption spectra suggest that the Pc-based cages can absorb infrared light, which is different from the visible-light absorption in Pc molecules. We further show that the excess uptake of hydrogen on MgPc and CaPc cages at 298 K and 100 bar (1 bar=0.1 MPa) is about 3.49 and 4.74 wt%, respectively. The present study provides new insight into Pc-based nanostructures with potential applications.
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Affiliation(s)
- Guizhi Zhu
- Department of Materials Science and Engineering, Peking University, Beijing 100871 (PR China)
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Chen M, Zhou H, Yu F, Yang H, Wang G, He J, Sun L. Tuning the layer-dependent doping effect of graphenes by C60. NANOSCALE 2013; 5:8359-8362. [PMID: 23832097 DOI: 10.1039/c3nr02055j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this work, the doping of n-layer graphenes with C60 is investigated via Raman spectroscopy. The results indicate that C60 can induce hole doping in graphenes, and that the doping level is closely related to the layer number of the graphenes. Moreover, the level of doping in the hybrid of C60 on graphene (C60/G) is more significant than that in the hybrid of graphene on C60 (G/C60).
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Affiliation(s)
- Minjiang Chen
- National Centre for Nanoscience and Technology, Beijing 100190, China
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33
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Lutz T, Grosse C, Dette C, Kabakchiev A, Schramm F, Ruben M, Gutzler R, Kuhnke K, Schlickum U, Kern K. Molecular orbital gates for plasmon excitation. NANO LETTERS 2013; 13:2846-2850. [PMID: 23688309 DOI: 10.1021/nl401177b] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Future combinations of plasmonics with nanometer-sized electronic circuits require strategies to control the electrical excitation of plasmons at the length scale of individual molecules. A unique tool to study the electrical plasmon excitation with ultimate resolution is scanning tunneling microscopy (STM). Inelastic tunnel processes generate plasmons in the tunnel gap that partially radiate into the far field where they are detectable as photons. Here we employ STM to study individual tris-(phenylpyridine)-iridium complexes on a C60 monolayer, and investigate the influence of their electronic structure on the plasmon excitation between the Ag(111) substrate and an Ag-covered Au tip. We demonstrate that the highest occupied molecular orbital serves as a spatially and energetically confined nanogate for plasmon excitation. This opens the way for using molecular tunnel junctions as electrically controlled plasmon sources.
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Affiliation(s)
- Theresa Lutz
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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34
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Smerdon JA, Rankin RB, Greeley JP, Guisinger NP, Guest JR. Chiral "pinwheel" heterojunctions self-assembled from C60 and pentacene. ACS NANO 2013; 7:3086-3094. [PMID: 23488794 DOI: 10.1021/nn304992c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate the self-assembly of C60 and pentacene (Pn) molecules into acceptor-donor heterostructures which are well-ordered and--despite the high degree of symmetry of the constituent molecules--chiral. Pn was deposited on Cu(111) to monolayer coverage, producing the random-tiling (R) phase as previously described. Atop R-phase Pn, postdeposited C60 molecules cause rearrangement of the Pn molecules into domains based on chiral supramolecular "pinwheels". These two molecules are the highest-symmetry achiral molecules so far observed to coalesce into chiral heterostructures. Also, the chiral pinwheels (composed of 1 C60 and 6 Pn each) may share Pn molecules in different ways to produce structures with different lattice parameters and degree of chirality. High-resolution scanning tunneling microscopy results and knowledge of adsorption sites allow the determination of these structures to a high degree of confidence. The measurement of chiral angles identical to those predicted is a further demonstration of the accuracy of the models. van der Waals density functional theory calculations reveal that the Pn molecules around each C60 are torsionally flexed around their long molecular axes and that there is charge transfer from C60 to Pn in each pinwheel.
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Affiliation(s)
- Joseph A Smerdon
- Department of Physics, University of Liverpool, Liverpool L69 3BX, United Kingdom
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35
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Karunakaran C, Jayabharathi J, Venkatesh Perumal M, Thanikachalam V, Kumar Thakur P. Electronic properties of phenanthrimidazoles as hole transport materials in organic light emitting devices and in photoelectron transfer to ZnO nanoparticles. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3100] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | | | | | - Prasoon Kumar Thakur
- Division of Nematology; Indian Agricultural Research Institute; New Delhi-12; India
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36
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Bajales N, Schmaus S, Miyamashi T, Wulfhekel W, Wilhelm J, Walz M, Stendel M, Bagrets A, Evers F, Ulas S, Kern B, Böttcher A, Kappes MM. C58 on Au(111): A scanning tunneling microscopy study. J Chem Phys 2013; 138:104703. [DOI: 10.1063/1.4793761] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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37
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Zhao A, Tan S, Li B, Wang B, Yang J, Hou JG. STM tip-assisted single molecule chemistry. Phys Chem Chem Phys 2013; 15:12428-41. [PMID: 23788046 DOI: 10.1039/c3cp51446c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Aidi Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale (HFNL), University of Science and Technology of China (USTC), Hefei, Anhui 230026, P R China
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38
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Franke KJ, Pascual JI. Effects of electron-vibration coupling in transport through single molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:394002. [PMID: 22964796 DOI: 10.1088/0953-8984/24/39/394002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Using scanning tunneling spectroscopy, we study the transport of electrons through C(60) molecules on different metal surfaces. When electrons tunnel through a molecule, they may excite molecular vibrations. A fingerprint of these processes is a characteristic sub-structure in the differential conductance spectra of the molecular junction reflecting the onset of vibrational excitation. Although the intensity of these processes is generally weak, they become more important as the resonant character of the transport mechanism increases. The detection of single vibrational levels crucially depends on the energy level alignment and lifetimes of excited states. In the limit of large current densities, resonant electron-vibration coupling leads to an energy accumulation in the molecule, which eventually leads to its decomposition. With our experiments on C(60) we are able to depict a molecular scale picture of how electrons interact with the vibrational degrees of freedom of single molecules in different transport regimes. This understanding helps in the development of stable molecular devices, which may also carry a switchable functionality.
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Affiliation(s)
- Katharina J Franke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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39
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Vijayaraghavan S, Écija D, Auwärter W, Joshi S, Seufert K, Seitsonen AP, Tashiro K, Barth JV. Selective supramolecular fullerene-porphyrin interactions and switching in surface-confined C60-Ce(TPP)2 dyads. NANO LETTERS 2012; 12:4077-4083. [PMID: 22765649 DOI: 10.1021/nl301534p] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The control of organic molecules, supramolecular complexes and donor-acceptor systems at interfaces is a key issue in the development of novel hybrid architectures for regulation of charge-carrier transport pathways in nanoelectronics or organic photovoltaics. However, at present little is known regarding the intricate features of stacked molecular nanostructures stabilized by noncovalent interactions. Here we explore at the single molecule level the geometry and electronic properties of model donor-acceptor dyads stabilized by van der Waals interactions on a single crystal Ag(111) support. Our combined scanning tunneling microscopy/spectroscopy (STM/STS) and first-principles computational modeling study reveals site-selective positioning of C(60) molecules on Ce(TPP)(2) porphyrin double-decker arrays with the fullerene centered on the π-system of the top bowl-shaped tetrapyrrole macrocycle. Three specific orientations of the C(60) cage in the van der Waals complex are identified that can be reversibly switched by STM manipulation protocols. Each configuration presents a distinct conductivity, which accounts for a tristable molecular switch and the tunability of the intradyad coupling. In addition, STS data evidence electronic decoupling of the hovering C(60) units from the metal substrate, a prerequisite for photophysical applications.
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40
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Pawlak R, Kawai S, Fremy S, Glatzel T, Meyer E. High-resolution imaging of C60 molecules using tuning-fork-based non-contact atomic force microscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:084005. [PMID: 22310075 DOI: 10.1088/0953-8984/24/8/084005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent advances in non-contact atomic force microscopy (nc-AFM) have led to the possibility of achieving unprecedented resolution within molecular structures, accomplished by probing short-range repulsive interaction forces. Here we investigate C(60) molecules adsorbed on KBr(111) and Cu(111) by tuning-fork-based nc-AFM. First, measurements of C(60) deposited on KBr(001) were conducted in cryogenic conditions revealing highly resolved nc-AFM images of the self-assembly. Using constant-frequency shift mode as well as three-dimensional spectroscopic measurements, we observe that the relatively weak molecule-substrate interaction generally leads to the disruption of molecular assembled structures when the tip is probing the short-range force regime. This particular issue hindered us in resolving the chemical structure of this molecule on the KBr surface. To obtain a better anchoring of C(60) molecules, nc-AFM measurements were performed on Cu(111). Sub-molecular resolutions within the molecules was achieved which allowed a direct and unambiguous visualization of their orientations on the supporting substrate. Furthermore, three-dimensional spectroscopic measurements of simultaneous force and current have been performed above the single molecules giving information of the C(60) molecular orientation as well as its local conductivity. We further discuss the different imaging modes in nc-AFM such as constant-frequency shift nc-AFM, constant-height nc-AFM and constant-current nc-AFM as well as three-dimensional spectroscopic measurement (3D-DFS) employed to achieve such resolution at the sub-molecular scale.
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Affiliation(s)
- R Pawlak
- Department of Physics, University of Basel, Basel, Switzerland.
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41
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Heinrich BW, Rastei MV, Choi DJ, Frederiksen T, Limot L. Engineering negative differential conductance with the Cu(111) surface state. PHYSICAL REVIEW LETTERS 2011; 107:246801. [PMID: 22243018 DOI: 10.1103/physrevlett.107.246801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Indexed: 05/31/2023]
Abstract
Low-temperature scanning tunneling microscopy and spectroscopy are employed to investigate electron tunneling from a C60-terminated tip into a Cu(111) surface. Tunneling between a C60 orbital and the Shockley surface states of copper is shown to produce negative differential conductance (NDC) contrary to conventional expectations. NDC can be tuned through barrier thickness or C60 orientation up to complete extinction. The orientation dependence of NDC is a result of a symmetry matching between the molecular tip and the surface states.
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Affiliation(s)
- B W Heinrich
- Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS Université de Strasbourg, F-67034 Strasbourg, France
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42
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Yee SK, Malen JA, Majumdar A, Segalman RA. Thermoelectricity in fullerene-metal heterojunctions. NANO LETTERS 2011; 11:4089-94. [PMID: 21882860 DOI: 10.1021/nl2014839] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Thermoelectricty in heterojunctions, where a single-molecule is trapped between metal electrodes, has been used to understand transport properties at organic-inorganic interfaces. (1) The transport in these systems is highly dependent on the energy level alignment between the molecular orbitals and the Fermi level (or work function) of the metal contacts. To date, the majority of single-molecule measurements have focused on simple small molecules where transport is dominated through the highest occupied molecular orbital. (2, 3) In these systems, energy level alignment is limited by the absence of electrode materials with low Fermi levels (i.e., large work functions). Alternatively, more controllable alignment between molecular orbitals and the Fermi level can be achieved with molecules whose transport is dominated by the lowest unoccupied molecular orbital (LUMO) because of readily available metals with lower work functions. Herein, we report molecular junction thermoelectric measurements of fullerene molecules (i.e., C(60), PCBM, and C(70)) trapped between metallic electrodes (i.e., Pt, Au, Ag). Fullerene junctions demonstrate the first strongly n-type molecular thermopower corresponding to transport through the LUMO, and the highest measured magnitude of molecular thermopower to date. While the electronic conductance of fullerenes is highly variable, due to fullerene's variable bonding geometries with the electrodes, the thermopower shows predictable trends based on the alignment of the LUMO with the work function of the electrodes. Both the magnitude and trend of the thermopower suggest that heterostructuring organic and inorganic materials at the nanoscale can further enhance thermoelectric performance, therein providing a new pathway for designing thermoelectric materials.
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Affiliation(s)
- Shannon K Yee
- Department of Mechanical Engineering, University of California, Berkeley, California 94720, United States
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43
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Néel N, Kröger J, Berndt R. Two-level conductance fluctuations of a single-molecule junction. NANO LETTERS 2011; 11:3593-3596. [PMID: 21854026 DOI: 10.1021/nl201327c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The conductance of a single-molecule junction in a low-temperature scanning tunneling microscope has been measured at nanosecond time resolution. In a transition region between tunneling and contact the conductance exhibits rapid two-level fluctuations which are attributed to different geometries of the junction. The voltage dependence of the fluctuations indicates that electrons injected into the lowest unoccupied molecular orbital may efficiently couple to molecular vibrations.
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Affiliation(s)
- N Néel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany.
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44
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Henzl J, Morgenstern K. The frontier orbitals of a push-pull azobenzene adsorbed on a metal surface in different bonding geometries investigated by scanning tunneling spectroscopy and spectroscopy mapping. J Chem Phys 2011; 135:094702. [PMID: 21913778 DOI: 10.1063/1.3631340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The electronic structure of 4-anilino-4'-nitroazobenzene superstructures formed on Au(111) at 250 K is investigated by low temperature scanning tunneling microscopy, scanning tunneling spectroscopy, and dI/dV mapping at 5 K. Changes in the dI/dV maps of this push-pull molecule reflect the spatial distribution of the frontier orbitals on the molecular scale. Spectra of the trans- and the cis∗-isomer differ between themselves and in different parts of supramolecular assemblies. The relative importance of these differences is discussed.
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Affiliation(s)
- Jörg Henzl
- Institut für Festkörperphysik, Abteilung für atomare und molekulare Strukturen (ATMOS), Leibniz Universität Hannover, Appelstr. 2, D-30167 Hannover, Germany
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45
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Meyer J, Wadewitz A, Lokamani, Toher C, Gresser R, Leo K, Riede M, Moresco F, Cuniberti G. Molecules for organic electronics studied one by one. Phys Chem Chem Phys 2011; 13:14421-6. [PMID: 21796307 DOI: 10.1039/c1cp20999j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electronic and geometrical structure of single difluoro-bora-1,3,5,7-tetraphenyl-aza-dipyrromethene (aza-BODIPY) molecules adsorbed on the Au(111) surface is investigated by low temperature scanning tunneling microscopy and spectroscopy in conjunction with ab initio density functional theory simulations of the density of states and of the interaction with the substrate. Our DFT calculations indicate that the aza-bodipy molecule forms a chemical bond with the Au(111) substrate, with distortion of the molecular geometry and significant charge transfer between the molecule and the substrate. Nevertheless, most likely due to the low corrugation of the Au(111) surface, diffusion of the molecule is observed for applied bias in excess of 1 V.
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Affiliation(s)
- Jörg Meyer
- Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, 01062 Dresden, Germany
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46
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Feng M, Zhao J, Huang T, Zhu X, Petek H. The electronic properties of superatom states of hollow molecules. Acc Chem Res 2011; 44:360-8. [PMID: 21413734 DOI: 10.1021/ar1001445] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electronic and optical properties of molecules and molecular solids are traditionally considered from the perspective of the frontier orbitals and their intermolecular interactions. How molecules condense into crystalline solids, however, is mainly attributed to the long-range polarization interaction. In this Account, we show that long-range polarization also introduces a distinctive set of diffuse molecular electronic states, which in quantum structures or solids can combine into nearly-free-electron (NFE) bands. These NFE properties, which are usually associated with good metals, are vividly evident in sp(2) hybridized carbon materials, specifically graphene and its derivatives. The polarization interaction is primarily manifested in the screening of an external charge at a solid/vacuum interface. It is responsible for the universal image potential and the associated unoccupied image potential (IP) states, which are observed even at the He liquid/vacuum interface. The molecular electronic properties that we describe are derived from the IP states of graphene, which float above and below the molecular plane and undergo free motion parallel to it. Rolling or wrapping a graphene sheet into a nanotube or a fullerene transforms the IP states into diffuse atom-like orbitals that are bound primarily to hollow molecular cores, rather than the component atoms. Therefore, we named them the superatom molecular orbitals (SAMOs). Like the excitonic states of semiconductor nanostructures or the plasmonic resonances of metallic nanoparticles, SAMOs of fullerene molecules, separated by their van der Waals distance, can combine to form diatomic molecule-like orbitals of C(60) dimers. For larger aggregates, they form NFE bands of superatomic quantum structures and solids. The overlap of the diffuse SAMO wavefunctions in van der Waals solids provides a different paradigm for band formation than the valence or conduction bands formed by interaction of the more tightly bound, directional highest occupied molecular orbitals (HOMOs) or the lowest unoccupied molecular orbitals (LUMOs). Therefore, SAMO wavefunctions provide insights into the design of molecular materials with potentially superior properties for electronics. Physicists and chemists have thought of fullerenes as atom-like building blocks of electronic materials, and superatom properties have been attributed to other elemental gas-phase clusters based on their size-dependent electronic structure and reactivity. Only in the case of fullerenes, however, do the superatom properties survive as delocalized electronic bands even in the condensed phase. We emphasize, however, that the superatom states and their bands are usually unoccupied and therefore do not contribute to intermolecular bonding. Instead, their significance lies in the electronic properties they confer when electrons are introduced, such as when they are excited optically or probed by the atomically sharp tip of a scanning tunneling microscope. We describe the IP states of graphene as the primary manifestation of the universal polarization response of a molecular sheet and how these states in turn define the NFE properties of materials derived from graphene, such as graphite, fullerenes, and nanotubes. Through low-temperature scanning tunneling microscopy (LT-STM), time-resolved two-photon photoemission spectroscopy (TR-2PP), and density functional theory (DFT), we describe the real and reciprocal space electronic properties of SAMOs for single C(60) molecules and their self-assembled 1D and 2D quantum structures on single-crystal metal surfaces.
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Affiliation(s)
- Min Feng
- Department of Physics and Astronomy and Petersen Institute of NanoScience and Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jin Zhao
- Department of Physics and Astronomy and Petersen Institute of NanoScience and Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui, China
| | - Tian Huang
- Department of Physics and Astronomy and Petersen Institute of NanoScience and Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Xiaoyang Zhu
- Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712, United States
| | - Hrvoje Petek
- Department of Physics and Astronomy and Petersen Institute of NanoScience and Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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47
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Gross L. Recent advances in submolecular resolution with scanning probe microscopy. Nat Chem 2011; 3:273-8. [DOI: 10.1038/nchem.1008] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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48
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Li B, Li Z, Yang J, Hou JG. STM studies of single molecules: molecular orbital aspects. Chem Commun (Camb) 2011; 47:2747-62. [DOI: 10.1039/c0cc03021j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Sørensen JK, Fock J, Pedersen AH, Petersen AB, Jennum K, Bechgaard K, Kilså K, Geskin V, Cornil J, Bjørnholm T, Nielsen MB. Fulleropyrrolidine End-Capped Molecular Wires for Molecular Electronics—Synthesis, Spectroscopic, Electrochemical, and Theoretical Characterization. J Org Chem 2010; 76:245-63. [PMID: 21133403 DOI: 10.1021/jo102066x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jakob Kryger Sørensen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Jeppe Fock
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Anders Holmen Pedersen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Asger B. Petersen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Karsten Jennum
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Klaus Bechgaard
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Kristine Kilså
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Victor Geskin
- Service de Chimie des Matériaux Nouveaux, University of Mons, Place du Parc 20, B-7000 Mons, Belgium
| | - Jérôme Cornil
- Service de Chimie des Matériaux Nouveaux, University of Mons, Place du Parc 20, B-7000 Mons, Belgium
| | - Thomas Bjørnholm
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Mogens Brøndsted Nielsen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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50
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Lu Y, Quardokus R, Lent CS, Justaud F, Lapinte C, Kandel SA. Charge Localization in Isolated Mixed-Valence Complexes: An STM and Theoretical Study. J Am Chem Soc 2010; 132:13519-24. [DOI: 10.1021/ja105958p] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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