1
|
Reimers JR, Li T, Birvé AP, Yang L, Aragonès AC, Fallon T, Kosov DS, Darwish N. Controlling piezoresistance in single molecules through the isomerisation of bullvalenes. Nat Commun 2023; 14:6089. [PMID: 37789027 PMCID: PMC10547723 DOI: 10.1038/s41467-023-41674-z] [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: 12/15/2022] [Accepted: 09/06/2023] [Indexed: 10/05/2023] Open
Abstract
Nanoscale electro-mechanical systems (NEMS) displaying piezoresistance offer unique measurement opportunities at the sub-cellular level, in detectors and sensors, and in emerging generations of integrated electronic devices. Here, we show a single-molecule NEMS piezoresistor that operates utilising constitutional and conformational isomerisation of individual diaryl-bullvalene molecules and can be switched at 850 Hz. Observations are made using scanning tunnelling microscopy break junction (STMBJ) techniques to characterise piezoresistance, combined with blinking (current-time) experiments that follow single-molecule reactions in real time. A kinetic Monte Carlo methodology (KMC) is developed to simulate isomerisation on the experimental timescale, parameterised using density-functional theory (DFT) combined with non-equilibrium Green's function (NEGF) calculations. Results indicate that piezoresistance is controlled by both constitutional and conformational isomerisation, occurring at rates that are either fast (equilibrium) or slow (non-equilibrium) compared to the experimental timescale. Two different types of STMBJ traces are observed, one typical of traditional experiments that are interpreted in terms of intramolecular isomerisation occurring on stable tipped-shaped metal-contact junctions, and another attributed to arise from junction‒interface restructuring induced by bullvalene isomerisation.
Collapse
Affiliation(s)
- Jeffrey R Reimers
- International Centre for Quantum and Molecular Structures and the Department of Physics, Shanghai University, Shanghai, 200444, China.
- School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW, 2007, Australia.
| | - Tiexin Li
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia
| | - André P Birvé
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Likun Yang
- International Centre for Quantum and Molecular Structures and the Department of Physics, Shanghai University, Shanghai, 200444, China
| | - Albert C Aragonès
- Department of Materials Science and Physical Chemistry, University of Barcelona, Marti i Franquès 1, 08028, Barcelona, Catalonia, Spain
- Institute of Theoretical and Computational Chemistry, University of Barcelona, Diagonal 645, 08028, Barcelona, Catalonia, Spain
| | - Thomas Fallon
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia.
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia.
| |
Collapse
|
2
|
Reimers JR, Yang J, Darwish N, Kosov DS. Silicon - single molecule - silicon circuits. Chem Sci 2021; 12:15870-15881. [PMID: 35024111 PMCID: PMC8672724 DOI: 10.1039/d1sc04943g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/28/2021] [Indexed: 12/23/2022] Open
Abstract
In 2020, silicon - molecule - silicon junctions were fabricated and shown to be on average one third as conductive as traditional junctions made using gold electrodes, but in some instances to be even more conductive, and significantly 3 times more extendable and 5 times more mechanically stable. Herein, calculations are performed of single-molecule junction structure and conductivity pertaining to blinking and scanning-tunnelling-microscopy (STM) break junction (STMBJ) experiments performed using chemisorbed 1,6-hexanedithiol linkers. Some strikingly different characteristics are found compared to analogous junctions formed using the metals which, to date, have dominated the field of molecular electronics. In the STMBJ experiment, following retraction of the STM tip after collision with the substrate, unterminated silicon surface dangling bonds are predicted to remain after reaction of the fresh tips with the dithiol solute. These dangling bonds occupy the silicon band gap and are predicted to facilitate extraordinary single-molecule conductivity. Enhanced junction extendibility is attributed to junction flexibility and the translation of adsorbed molecules between silicon dangling bonds. The calculations investigate a range of junction atomic-structural models using density-functional-theory (DFT) calculations of structure, often explored at 300 K using molecular dynamics (MD) simulations. These are aided by DFT calculations of barriers for passivation reactions of the dangling bonds. Thermally averaged conductivities are then evaluated using non-equilibrium Green's function (NEGF) methods. Countless applications through electronics, nanotechnology, photonics, and sensing are envisaged for this technology.
Collapse
Affiliation(s)
- Jeffrey R Reimers
- International Centre for Quantum and Molecular Structures and School of Physics, Shanghai University Shanghai 200444 China
- School of Mathematical and Physical Sciences, University of Technology Sydney NSW 2007 Australia
| | - Junhao Yang
- International Centre for Quantum and Molecular Structures and School of Physics, Shanghai University Shanghai 200444 China
| | - Nadim Darwish
- School of Molecular and Life Sciences, Curtin Institute of Functional Molecules and Interfaces, Curtin University Bentley WA 6102 Australia
| | - Daniel S Kosov
- College of Science and Engineering, James Cook University Townsville QLD 4811 Australia
| |
Collapse
|
3
|
Cuny J, Tarrat N, Spiegelman F, Huguenot A, Rapacioli M. Density-functional tight-binding approach for metal clusters, nanoparticles, surfaces and bulk: application to silver and gold. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:303001. [PMID: 29916820 DOI: 10.1088/1361-648x/aacd6c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Density-functional based tight-binding (DFTB) is an efficient quantum mechanical method that can describe a variety of systems, going from organic and inorganic compounds to metallic and hybrid materials. The present topical review addresses the ability and performance of DFTB to investigate energetic, structural, spectroscopic and dynamical properties of gold and silver materials. After a brief overview of the theoretical basis of DFTB, its parametrization and its transferability, we report its past and recent applications to gold and silver systems, including small clusters, nanoparticles, bulk and surfaces, bare and interacting with various organic and inorganic compounds. The range of applications covered by those studies goes from plasmonics and molecular electronics, to energy conversion and surface chemistry. Finally, perspectives of DFTB in the field of gold and silver surfaces and NPs are outlined.
Collapse
Affiliation(s)
- Jérôme Cuny
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Université de Toulouse III [UPS] and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | | | | | | | | |
Collapse
|
4
|
Kershaw VF, Kosov DS. Nonequilibrium Green’s function theory for nonadiabatic effects in quantum electron transport. J Chem Phys 2017; 147:224109. [DOI: 10.1063/1.5007071] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Vincent F. Kershaw
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Daniel S. Kosov
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| |
Collapse
|
5
|
Lykkebo J, Romano G, Gagliardi A, Pecchia A, Solomon GC. Single-molecule electronics: Cooling individual vibrational modes by the tunneling current. J Chem Phys 2016; 144:114310. [DOI: 10.1063/1.4943578] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Jacob Lykkebo
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Giuseppe Romano
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Alessio Gagliardi
- Technische Universität München, Electrical Engineering and Information Technology, Arcisstr. 21, 80333 München, Germany
| | - Alessandro Pecchia
- Consiglio Nazionale delle Ricerche, ISMN, Via Salaria Km 29.6, 00017 Monterotondo, Rome, Italy
| | - Gemma C. Solomon
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| |
Collapse
|
6
|
Gold surfaces and nanoparticles are protected by Au(0)-thiyl species and are destroyed when Au(I)-thiolates form. Proc Natl Acad Sci U S A 2016; 113:E1424-33. [PMID: 26929334 DOI: 10.1073/pnas.1600472113] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)-thiyl, with Au(I)-thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)-thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s-d hybridization and charge polarization effects that perturbatively mix in some Au(I)-thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)-thiolate involvement. Predictions that Brust-Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)-thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established.
Collapse
|
7
|
Villagómez CJ, Castanié F, Momblona C, Gauthier S, Zambelli T, Bouju X. Adsorption of single 1,8-octanedithiol molecules on Cu(100). Phys Chem Chem Phys 2016; 18:27521-27528. [DOI: 10.1039/c6cp04449b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
STM experiments and calculations have allowed identifying the most favorable conformation of a single octanedithiol molecule on a copper surface.
Collapse
Affiliation(s)
- Carlos J. Villagómez
- Instituto de Física
- Universidad Nacional Autónoma de México
- Mexico
- CEMES-CNRS
- 31055 Toulouse Cedex 4
| | - Fabien Castanié
- CEMES-CNRS
- 31055 Toulouse Cedex 4
- France
- Université de Toulouse
- UPS
| | - Cristina Momblona
- CEMES-CNRS
- 31055 Toulouse Cedex 4
- France
- Instituto de Nanociencia de Aragoń (INA)
- Edificio i+d
| | | | - Tomaso Zambelli
- CEMES-CNRS
- 31055 Toulouse Cedex 4
- France
- Swiss Fed. Inst. Technlo
- Inst. Biomed. Engn
| | | |
Collapse
|
8
|
Abstract
David Craig (1919–2015) left us with a lasting legacy concerning basic understanding of chemical spectroscopy and bonding. This is expressed in terms of some of the recent achievements of my own research career, with a focus on integration of Craig’s theories with those of Noel Hush to solve fundamental problems in photosynthesis, molecular electronics (particularly in regard to the molecules synthesized by Maxwell Crossley), and self-assembled monolayer structure and function. Reviewed in particular is the relation of Craig’s legacy to: the 50-year struggle to assign the visible absorption spectrum of arguably the world’s most significant chromophore, chlorophyll; general theories for chemical bonding and structure extending Hush’s adiabatic theory of electron-transfer processes; inelastic electron-tunnelling spectroscopy (IETS); chemical quantum entanglement and the Penrose–Hameroff model for quantum consciousness; synthetic design strategies for NMR quantum computing; Gibbs free-energy measurements and calculations for formation and polymorphism of organic self-assembled monolayers on graphite surfaces from organic solution; and understanding the basic chemical processes involved in the formation of gold surfaces and nanoparticles protected by sulfur-bound ligands, ligands whose form is that of Au0-thiyl rather than its commonly believed AuI-thiolate tautomer.
Collapse
|
9
|
Jiang Z, Wang H, Sanvito S, Hou S. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface. J Chem Phys 2015; 143:234709. [PMID: 26696072 DOI: 10.1063/1.4938087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4pz atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.
Collapse
Affiliation(s)
- Zhuoling Jiang
- Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Hao Wang
- Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Shimin Hou
- Centre for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| |
Collapse
|
10
|
Affiliation(s)
- Robert M. Metzger
- Laboratory for Molecular
Electronics, Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, Alabama 35487-0336, United States
| |
Collapse
|
11
|
Lu SY, Lin JS. A nano Ag 5 cluster tip probing the vertical transfer of CO (ads) adsorbed on Ag(110) with simulated inelastic electron tunneling spectroscopy. RSC Adv 2015. [DOI: 10.1039/c5ra06728f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A nano Ag5 tip probing the transfer of CO(ads) on Ag(110) surface is investigated with simulated inelastic electron tunneling spectroscopy generated by combining DFT-based MD simulations with a FT-ACF of the derivative of local density of states.
Collapse
Affiliation(s)
- Shao-Yu Lu
- Department of Chemistry
- Tamkang University
- Tamsui
- Taiwan 25137
| | - Jyh-Shing Lin
- Department of Chemistry
- Tamkang University
- Tamsui
- Taiwan 25137
| |
Collapse
|
12
|
Ding Z, Sun Z, Li G, Meng F, Wu M, Ma Y, Chen X. The inelastic electron tunneling spectroscopy of curved finite-sized graphene nanoribbon based molecular devices. RSC Adv 2015. [DOI: 10.1039/c5ra09727d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The inelastic electron scattering properties of the molecular devices of curved finite-sized graphene nanoribbon (GNR) slices have been studied by combining the density functional theory and Green's function method.
Collapse
Affiliation(s)
- Zongling Ding
- School of Physics and Material Science
- Anhui University
- Hefei, China
- Co-operative Innovation Research Center for Weak Signal-Detecting Materials and Devices Integration
- Anhui University
| | - Zhaoqi Sun
- School of Physics and Material Science
- Anhui University
- Hefei, China
| | - Guang Li
- School of Physics and Material Science
- Anhui University
- Hefei, China
| | - Fanming Meng
- School of Physics and Material Science
- Anhui University
- Hefei, China
| | - Mingzai Wu
- School of Physics and Material Science
- Anhui University
- Hefei, China
| | - Yongqing Ma
- School of Physics and Material Science
- Anhui University
- Hefei, China
| | - Xiaoshuang Chen
- National Lab. of Infrared Physics
- Shanghai Institute for Technical Physics
- Chinese Academy of Sciences
- Shanghai, China
| |
Collapse
|
13
|
Lykkebo J, Gagliardi A, Pecchia A, Solomon GC. IETS and quantum interference: Propensity rules in the presence of an interference feature. J Chem Phys 2014; 141:124119. [DOI: 10.1063/1.4896234] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jacob Lykkebo
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Alessio Gagliardi
- Technische Universität München, Electrical Engineering and Information Tech., Arcisstr. 21, 80333 München, Germany
| | - Alessandro Pecchia
- Consiglio Nazionale delle Ricerche, ISMN, Via Salaria km 29.6, 00017 Monterotondo (Rome), Italy
| | - Gemma C. Solomon
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| |
Collapse
|
14
|
Lykkebo J, Gagliardi A, Pecchia A, Solomon GC. Strong overtones modes in inelastic electron tunneling spectroscopy with cross-conjugated molecules: a prediction from theory. ACS NANO 2013; 7:9183-94. [PMID: 24067128 PMCID: PMC3807527 DOI: 10.1021/nn4037915] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/19/2013] [Indexed: 05/31/2023]
Abstract
Cross-conjugated molecules are known to exhibit destructive quantum interference, a property that has recently received considerable attention in single-molecule electronics. Destructive quantum interference can be understood as an antiresonance in the elastic transmission near the Fermi energy and leading to suppressed levels of elastic current. In most theoretical studies, only the elastic contributions to the current are taken into account. In this paper, we study the inelastic contributions to the current in cross-conjugated molecules and find that while the inelastic contribution to the current is larger than for molecules without interference, the overall behavior of the molecule is still dominated by the quantum interference feature. Second, an ongoing challenge for single molecule electronics is understanding and controlling the local geometry at the molecule-surface interface. With this in mind, we investigate a spectroscopic method capable of providing insight into these junctions for cross-conjugated molecules: inelastic electron tunneling spectroscopy (IETS). IETS has the advantage that the molecule interface is probed directly by the tunneling current. Previously, it has been thought that overtones are not observable in IETS. Here, overtones are predicted to be strong and, in some cases, the dominant spectroscopic features. We study the origin of the overtones and find that the interference features in these molecules are the key ingredient. The interference feature is a property of the transmission channels of the π system only, and consequently, in the vicinity of the interference feature, the transmission channels of the σ system and the π system become equally transmissive. This allows for scattering between the different transmission channels, which serves as a pathway to bypass the interference feature. A simple model calculation is able to reproduce the results obtained from atomistic calculations, and we use this to interpret these findings.
Collapse
Affiliation(s)
- Jacob Lykkebo
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Alessio Gagliardi
- Department of Electronic Engineering, Università di Roma “Tor Vergata”, Via del Politecnico 1, 00133 Rome, Italy
| | - Alessandro Pecchia
- Consiglio Nazionale delle Ricerche, ISMN, Via Salaria km 29.6, 00017 Monterotondo, Rome, Italy
| | - Gemma C. Solomon
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| |
Collapse
|
15
|
Feugmo CGT, Champagne B, Caudano Y, Cecchet F, Chabal YJ, Liégeois V. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:124111. [PMID: 22394578 DOI: 10.1088/0953-8984/24/12/124111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement.
Collapse
Affiliation(s)
- Conrard Giresse Tetsassi Feugmo
- Laboratory of Theoretical Chemistry (LCT), Unité de Chimie-Physique Théorique et Structurale (UCPTS), FUNDP, Rue de Bruxelles, 61, B-5000 Namur, Belgium
| | | | | | | | | | | |
Collapse
|
16
|
Hihath J, Bruot C, Nakamura H, Asai Y, Díez-Pérez I, Lee Y, Yu L, Tao N. Inelastic transport and low-bias rectification in a single-molecule diode. ACS NANO 2011; 5:8331-8339. [PMID: 21932824 DOI: 10.1021/nn2030644] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Designing, controlling, and understanding rectification behavior in molecular-scale devices has been a goal of the molecular electronics community for many years. Here we study the transport behavior of a single molecule diode, and its nonrectifying, symmetric counterpart at low temperatures, and at both low and high biases to help elucidate the electron-phonon interactions and transport mechanisms in the rectifying system. We find that the onset of current rectification occurs at low biases, indicating a significant change in the elastic transport pathway. However, the peaks in the inelastic electron tunneling (IET) spectrum are antisymmetric about zero bias and show no significant changes in energy or intensity in the forward or reverse bias directions, indicating that despite the change in the elastic transmission probability there is little impact on the inelastic pathway. These results agree with first principles calculations performed to evaluate the IETS, which also allow us to identify which modes are active in the single molecule junction.
Collapse
Affiliation(s)
- Joshua Hihath
- The Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University School of Electrical, Energy and Computer Engineering, 1001 S. McAllister Avenue, Tempe, Arizona 85281-5801, United States
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Molecular electronic junction transport: some pathways and some ideas. Top Curr Chem (Cham) 2011. [PMID: 21915776 DOI: 10.1007/128_2011_227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
When a single molecule, or a collection of molecules, is placed between two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and focuses on mechanism, structure/function relations, regimes and mechanisms of transport, some molecular regularities, and some substantial challenges facing the field. Because there are many regimes and mechanisms in transport junctions, we will discuss time scales, geometries, and inelastic scattering methods for trying to determine the properties of molecules within these junctions. Finally, we discuss some device applications, some outstanding problems, and some future directions.
Collapse
|
18
|
Renaud N, Hliwa M, Joachim C. Single molecule logical devices. Top Curr Chem (Cham) 2011; 313:217-68. [PMID: 21826604 DOI: 10.1007/128_2011_222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
After almost 40 years of development, molecular electronics has given birth to many exciting ideas that range from molecular wires to molecular qubit-based quantum computers. This chapter reviews our efforts to answer a simple question: how smart can a single molecule be? In our case a molecule able to perform a simple Boolean function is a child prodigy. Following the Aviram and Ratner approach, these molecules are inserted between several conducting electrodes. The electronic conduction of the resulting molecular junction is extremely sensitive to the chemical nature of the molecule. Therefore designing this latter correctly allows the implementation of a given function inside the molecular junction. Throughout the chapter different approaches are reviewed, from hybrid devices to quantum molecular logic gates. We particularly stress that one can implement an entire logic circuit in a single molecule, using either classical-like intramolecular connections, or a deformation of the molecular orbitals induced by a conformational change of the molecule. These approaches are radically different from the hybrid-device approach, where several molecules are connected together to build the circuit.
Collapse
Affiliation(s)
- Nicolas Renaud
- Department of Chemistry, Northwestern University, Evanston, IL 60208-3113, USA.
| | | | | |
Collapse
|
19
|
Kim Y, Hellmuth TJ, Bürkle M, Pauly F, Scheer E. Characteristics of amine-ended and thiol-ended alkane single-molecule junctions revealed by inelastic electron tunneling spectroscopy. ACS NANO 2011; 5:4104-11. [PMID: 21506567 DOI: 10.1021/nn200759s] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A combined experimental and theoretical analysis of the charge transport through single-molecule junctions is performed to define the influence of molecular end groups for increasing electrode separation. For both amine-ended and thiol-ended octanes contacted to gold electrodes, we study signatures of chain formation by analyzing kinks in conductance traces, the junction length, and inelastic electron tunneling spectroscopy. The results show that for amine-ended molecular junctions no atomic chains are pulled under stretching, whereas the Au electrodes strongly deform for thiol-ended molecular junctions. This advanced approach hence provides unambiguous evidence that the amine anchors bind only weakly to Au.
Collapse
Affiliation(s)
- Youngsang Kim
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | | | | | | | | |
Collapse
|
20
|
Kim Y, Song H, Strigl F, Pernau HF, Lee T, Scheer E. Conductance and vibrational states of single-molecule junctions controlled by mechanical stretching and material variation. PHYSICAL REVIEW LETTERS 2011; 106:196804. [PMID: 21668188 DOI: 10.1103/physrevlett.106.196804] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Indexed: 05/14/2023]
Abstract
The changes of molecular conformation, contact geometry, and metal-molecule bonding are revealed by inelastic-electron-tunneling spectroscopy measurements characterizing the molecular vibrational modes and the metal-phonon modes in alkanedithiol molecular junctions at low temperature. Combining inelastic-electron-tunneling spectroscopy with mechanical control and electrode material variation (Au or Pt) enables separating the influence of contact geometry and of molecular conformation. The mechanical strain of different electrode materials can be imposed onto the molecule, opening a new route for controlling the charge transport through individual molecules.
Collapse
Affiliation(s)
- Youngsang Kim
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
| | | | | | | | | | | |
Collapse
|
21
|
Gorjizadeh N, Farajian AA, Kawazoe Y. Non-coherent transport in carbon chains. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:075301. [PMID: 21411880 DOI: 10.1088/0953-8984/23/7/075301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The effect of electron-phonon (e-ph) interaction on the conductance of carbon chains is investigated by a non-equilibrium Green's function technique combined with a four-orbitals-per-atom tight-binding Hamiltonian. The optimized structure of the chain is found to be the semiconducting polyyne type (···-C≡C-C≡C-···). Our results show that the conductance of a carbon chain attached to two fixed contacts decreases due to e-ph interaction, and this reduction is stronger for longitudinal phonon modes which decrease the hopping energy between carbon atoms. Study of individual phonon modes reveals that emission of longitudinal phonons is stronger than that of transverse modes at room temperature, while absorption of transverse phonons is dominant. Conductance at finite temperature is also studied by considering the overall phonon effects; this shows that the reduction of the conductance is stronger at higher temperatures. The results are explained on the basis of the unique features of the carbon chain band structure.
Collapse
Affiliation(s)
- Narjes Gorjizadeh
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
| | | | | |
Collapse
|
22
|
Fock J, Sørensen JK, Lörtscher E, Vosch T, Martin CA, Riel H, Kilså K, Bjørnholm T, van der Zant H. A statistical approach to inelastic electron tunneling spectroscopy on fullerene-terminated molecules. Phys Chem Chem Phys 2011; 13:14325-32. [DOI: 10.1039/c1cp20861f] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
23
|
Okabayashi N, Paulsson M, Ueba H, Konda Y, Komeda T. Site selective inelastic electron tunneling spectroscopy probed by isotope labeling. NANO LETTERS 2010; 10:2950-2955. [PMID: 20698608 DOI: 10.1021/nl1011323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We study inelastic scattering in alkanethiol self-assembled monolayers using isotope labeling and unambiguously determine which molecular vibrations are active in the inelastic electron tunneling spectroscopy. The selective deuteration of the molecule also allows us to show that the different parts of the molecule contribute approximately equally to inelastic signal. Our first principles calculations confirm the experimental results and provide insights on electron transport through molecules.
Collapse
Affiliation(s)
- Norio Okabayashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | | | | | | | | |
Collapse
|
24
|
Okabayashi N, Komeda T. Identification of a deuterated alkanethiol inserted in a hydrogenated alkanethiol self-assembled monolayer by mapping of an inelastic tunneling signal. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:084101. [PMID: 20815615 DOI: 10.1063/1.3469777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We show an experimental technique for visualizing distributions of vibrational modes of molecules through mapping of an inelastic tunneling signal with a scanning tunneling microscope. A topographic information and d(2)I/dV(2) signal processed by a lock-in amplifier were simultaneously imaged, where the feedback loop for the tunneling gap was engaged and a modulation voltage was superimposed to the gap voltage. The current signal used for the tunneling gap control was tuned by the filtering in order to minimize the response of the feedback loop caused by the modulation voltage. The effectiveness of this technique was demonstrated for a self-assembled monolayer composed of a mixture of normal and deuterated hexanethiol molecules, where both molecules have the same molecular length and the former was embedded in the matrix of the latter. Two types of molecules were successfully discriminated by chemical properties.
Collapse
Affiliation(s)
- Norio Okabayashi
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1, Katahira, Aoba, Sendai 980-8577, Japan
| | | |
Collapse
|
25
|
Okabayashi N, Paulsson M, Ueba H, Konda Y, Komeda T. Inelastic tunneling spectroscopy of alkanethiol molecules: high-resolution spectroscopy and theoretical simulations. PHYSICAL REVIEW LETTERS 2010; 104:077801. [PMID: 20366914 DOI: 10.1103/physrevlett.104.077801] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Indexed: 05/29/2023]
Abstract
We investigate inelastic electron tunneling spectroscopy (IETS) for alkanethiol self-assembled monolayers (SAM) with a scanning tunneling microscope and compare it to first-principles calculations. Using a combination of partial deuteration of the molecule and high-resolution measurements, we identify and differentiate between methyl (CH3) and methylene (CH2) groups and their symmetric and asymmetric C-H stretch modes. The calculations agree quantitatively with the measured IETS in producing the weight of the symmetric and asymmetric C-H stretch modes while the methylene stretch mode is largely underestimated. We further show that inelastic intermolecular scattering is important in the SAM by plotting the theoretical current densities.
Collapse
Affiliation(s)
- Norio Okabayashi
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, 980-8577, Japan
| | | | | | | | | |
Collapse
|
26
|
Jorn R, Seideman T. Competition between current-induced excitation and bath-induced decoherence in molecular junctions. J Chem Phys 2009; 131:244114. [DOI: 10.1063/1.3276281] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
|
27
|
Whitesides R, Frenklach M. Detailed Kinetic Monte Carlo Simulations of Graphene-Edge Growth. J Phys Chem A 2009; 114:689-703. [DOI: 10.1021/jp906541a] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Russell Whitesides
- Department of Mechanical Engineering, University of California, and Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Michael Frenklach
- Department of Mechanical Engineering, University of California, and Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| |
Collapse
|
28
|
Xiao D, Skourtis SS, Rubtsov IV, Beratan DN. Turning charge transfer on and off in a molecular interferometer with vibronic pathways. NANO LETTERS 2009; 9:1818-1823. [PMID: 19435376 DOI: 10.1021/nl8037695] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Inelastic electron-transfer kinetics in molecules with electron donor and acceptor units connected by a bridge is expected to be sensitive to bridge-localized vibronic interactions. Here, we show how inelastic electron transfer may be turned on and off in a double-slit style experiment that uses the molecule as an interferometer. We describe donor-acceptor interactions in terms of interfering vibronic coupling pathways that can be actively selected ("labeled") when pathway-specific vibrations are excited by infrared radiation. Thus, inelastic tunneling may be actively controlled, and we suggest strategies for building molecular scale quantum interferometers and switches based on this phenomenon.
Collapse
Affiliation(s)
- Dequan Xiao
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | | | | | | |
Collapse
|
29
|
Troisi A. Inelastic electron tunnelling in saturated molecules with different functional groups: correlations and symmetry considerations from a computational study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:374111. [PMID: 21694418 DOI: 10.1088/0953-8984/20/37/374111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The inelastic electron tunnelling (IET) spectra of a series of molecules with the commonest functional groups are evaluated computationally. It is found that ether, secondary amine and thioether groups do not leave any characteristic signatures on the IET spectrum (in comparison with simple alkanes) and they cannot be used as 'tracers' for the tunnelling path of the electron. In contrast, carbonyl and ester groups modify the appearance of the IET spectrum considerably. The series of computations was also used to validate, for the case of saturated molecules, the propensity rules for IET spectroscopy proposed in the literature. It is found that totally symmetric vibrations give the largest contribution to the spectrum and that there is no correlation between IET and infrared or Raman absorption intensities.
Collapse
Affiliation(s)
- Alessandro Troisi
- Department of Chemistry and Centre of Scientific Computing, University of Warwick, Coventry CV4 7AL, UK
| |
Collapse
|
30
|
Hihath J, Arroyo CR, Rubio-Bollinger G, Tao N, Agraït N. Study of electron-phonon interactions in a single molecule covalently connected to two electrodes. NANO LETTERS 2008; 8:1673-1678. [PMID: 18457456 DOI: 10.1021/nl080580e] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Presented here is a study of electron-phonon interactions in a single molecule junction where the molecule is covalently connected to two electrodes. In this system, vibration modes in a single molecule junction are measured by sweeping the bias voltage between the two electrodes and recording the differential conductance while the strain in the junction is changed by separating the two electrodes. This unique approach allows changes in conductance to be compared to changes in the configuration of a single molecule junction. This system opens a new door for characterizing single molecule junctions and a better understanding of the relationship between molecular conductance, electron-phonon interactions, and configuration.
Collapse
Affiliation(s)
- Joshua Hihath
- Department of Electrical Engineering, Center for Solid State Electronics, Arizona State University, Tempe, AZ 85287-5706, USA
| | | | | | | | | |
Collapse
|
31
|
Galperin M, Tretiak S. Linear optical response of current-carrying molecular junction: A nonequilibrium Green’s function–time-dependent density functional theory approach. J Chem Phys 2008; 128:124705. [DOI: 10.1063/1.2876011] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
32
|
Wohlthat S, Pauly F, Reimers JR. The conduction properties of α,ω-diaminoalkanes and hydrazine bridging gold electrodes. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.02.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
33
|
Galperin M, Ratner MA, Nitzan A, Troisi A. Nuclear Coupling and Polarization in Molecular Transport Junctions: Beyond Tunneling to Function. Science 2008; 319:1056-60. [DOI: 10.1126/science.1146556] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
|
34
|
Kula M, Luo Y. Effects of intermolecular interaction on inelastic electron tunneling spectra. J Chem Phys 2008; 128:064705. [DOI: 10.1063/1.2832304] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
35
|
|
36
|
|
37
|
Long DP, Troisi A. Inelastic Electron Tunneling Spectroscopy of Alkane Monolayers with Dissimilar Attachment Chemistry to Gold. J Am Chem Soc 2007; 129:15303-10. [DOI: 10.1021/ja074970z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- David P. Long
- Contribution from the Research and Development Center, Science Applications International Corporation (SAIC), 9460 Innovation Drive, Manassas, Virginia 20110, and Department of Chemistry and Centre of Scientific Computing, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, U.K
| | - Alessandro Troisi
- Contribution from the Research and Development Center, Science Applications International Corporation (SAIC), 9460 Innovation Drive, Manassas, Virginia 20110, and Department of Chemistry and Centre of Scientific Computing, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, U.K
| |
Collapse
|
38
|
Huang Z, Chen F, D'agosta R, Bennett PA, Di Ventra M, Tao N. Local ionic and electron heating in single-molecule junctions. NATURE NANOTECHNOLOGY 2007; 2:698-703. [PMID: 18654408 DOI: 10.1038/nnano.2007.345] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 09/26/2007] [Indexed: 05/26/2023]
Abstract
A basic aim in molecular electronics is to understand transport through a single molecule connected to two electrodes. Substantial progress towards this goal has been made over the past decade as a result of advances in both experimental techniques and theoretical methods. Nonetheless, a fundamental and technologically important issue, current-induced local heating of molecules, has received much less attention. Here, we report on a combined experimental and theoretical study of local heating in single molecules (6-, 8- and 10-alkanedithiol) covalently attached to two gold electrodes as a function of applied bias and molecular length. We find that the effective local temperature of the molecular junction first increases with applied bias, and then decreases after reaching a maximum. At fixed bias, the effective temperature decreases with increasing molecular length. These experimental findings are in agreement with hydrodynamic predictions, which include both electron-phonon and electron-electron interactions.
Collapse
|
39
|
Troisi A, Beebe JM, Picraux LB, van Zee RD, Stewart DR, Ratner MA, Kushmerick JG. Tracing electronic pathways in molecules by using inelastic tunneling spectroscopy. Proc Natl Acad Sci U S A 2007; 104:14255-9. [PMID: 17726099 PMCID: PMC1964821 DOI: 10.1073/pnas.0704208104] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Using inelastic electron tunneling spectroscopy (IETS) to measure the vibronic structure of nonequilibrium molecular transport, aided by a quantitative interpretation scheme based on Green's function-density functional theory methods, we are able to characterize the actual pathways that the electrons traverse when moving through a molecule in a molecular transport junction. We show that the IETS observations directly index electron tunneling pathways along the given normal coordinates of the molecule. One can then interpret the maxima in the IETS spectrum in terms of the specific paths that the electrons follow as they traverse the molecular junction. Therefore, IETS measurements not only prove (by the appearance of molecular vibrational frequencies in the spectrum) that the tunneling charges, in fact, pass through the molecule, but also can be used to determine the transport pathways and how they change with the geometry and placement of molecules in junctions.
Collapse
Affiliation(s)
- Alessandro Troisi
- Department of Chemistry and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Jeremy M. Beebe
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Laura B. Picraux
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Roger D. van Zee
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | | | - Mark A. Ratner
- Department of Chemistry and Institute of Nanotechnology, Northwestern University, Evanston, IL 60208
- To whom correspondence should be addressed. E-mail:
| | | |
Collapse
|
40
|
Reimers JR, Solomon GC, Gagliardi A, Bilić A, Hush NS, Frauenheim T, Di Carlo A, Pecchia A. The Green's Function Density Functional Tight-Binding (gDFTB) Method for Molecular Electronic Conduction. J Phys Chem A 2007; 111:5692-702. [PMID: 17530826 DOI: 10.1021/jp070598y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A review is presented of the nonequilibrium Green's function (NEGF) method "gDFTB" for evaluating elastic and inelastic conduction through single molecules employing the density functional tight-binding (DFTB) electronic structure method. This focuses on the possible advantages that DFTB implementations of NEGF have over conventional methods based on density functional theory, including not only the ability to treat large irregular metal-molecule junctions with high nonequilibrium thermal distributions but perhaps also the ability to treat dispersive forces, bond breakage, and open-shell systems and to avoid large band lineup errors. New results are presented indicating that DFTB provides a useful depiction of simple gold-thiol interactions. Symmetry is implemented in DFTB, and the advantages it brings in terms of large savings of computational resources with significant increase in numerical stability are described. The power of DFTB is then harnessed to allow the use of gDFTB as a real-time tool to discover the nature of the forces that control inelastic charge transport through molecules and the role of molecular symmetry in determining both elastic and inelastic transport. Future directions for the development of the method are discussed.
Collapse
|
41
|
Yu LH, Zangmeister CD, Kushmerick JG. Origin of discrepancies in inelastic electron tunneling spectra of molecular junctions. PHYSICAL REVIEW LETTERS 2007; 98:206803. [PMID: 17677727 DOI: 10.1103/physrevlett.98.206803] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Indexed: 05/16/2023]
Abstract
We report inelastic electron tunneling spectroscopy (IETS) of multilayer molecular junctions with and without incorporated metal nanoparticles. The incorporation of metal nanoparticles into our devices leads to enhanced IET intensity and a modified line shape for some vibrational modes. The enhancement and line-shape modification are both the result of a low lying hybrid metal nanoparticle-molecule electronic level. These observations explain the apparent discrepancy between earlier IETS measurements of alkane thiolate junctions by Kushmerick et al. [Nano Lett. 4, 639 (2004)] and Wang et al. [Nano Lett. 4, 643 (2004)].
Collapse
Affiliation(s)
- Lam H Yu
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | | | | |
Collapse
|
42
|
Beebe JM, Moore HJ, Lee TR, Kushmerick JG. Vibronic coupling in semifluorinated alkanethiol junctions: implications for selection rules in inelastic electron tunneling spectroscopy. NANO LETTERS 2007; 7:1364-8. [PMID: 17430006 DOI: 10.1021/nl070460r] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Determining the selection rules for the interaction of tunneling charge carriers with molecular vibrational modes is important for a complete understanding of charge transport in molecular electronic junctions. Here, we report the low-temperature charge transport characteristics for junctions formed from hexadecanethiol molecules having varying degrees of fluorination. Our results demonstrate that C-F vibrations are not observed in inelastic electron tunneling spectroscopy (IETS). Because C-F vibrations are almost purely dipole transitions, the insensitivity to fluorine substitution implies that Raman modes are preferred over infrared modes. Further, the lack of attenuation of the C-H vibrational modes with fluorine substitution suggests that either the scattering cross section is not an additive quantity or the physical position of a vibrational mode within the junction influences whether the transition is observed in IETS.
Collapse
Affiliation(s)
- Jeremy M Beebe
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | | | | | | |
Collapse
|
43
|
Troisi A, Ratner MA. Inelastic insights for molecular tunneling pathways: Bypassing the terminal groups. Phys Chem Chem Phys 2007; 9:2421-7. [PMID: 17492106 DOI: 10.1039/b702377d] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
As an example of the use of inelastic transport to deduce structure in molecular transport junctions, we compute the orientation dependence of the Inelastic Electron Tunneling (IET) spectrum of the 1-pentane monothiolate. We find that upon increasing the tilting angle of the molecule with respect to the normal to the electrode the spectrum changes as the intensity of some vibrations is enhanced. These differences occur because for higher tilting angles the tunneling path that bypasses the terminal group grows in importance. IETS can therefore be used to establish the molecular orientation in junctions terminating with alkyl chains and to investigate experimentally the relative importance of the available tunneling paths.
Collapse
Affiliation(s)
- Alessandro Troisi
- Department of Chemistry and Centre of Scientific Computing, University of Warwick, Coventry, UK.
| | | |
Collapse
|
44
|
Troisi A, Ratner MA. Propensity rules for inelastic electron tunneling spectroscopy of single-molecule transport junctions. J Chem Phys 2006; 125:214709. [PMID: 17166042 DOI: 10.1063/1.2390698] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Using a perturbative approach to simple model systems, we derive useful propensity rules for inelastic electron tunneling spectroscopy (IETS) of molecular wire junctions. We examine the circumstances under which this spectroscopy (that has no rigorous selection rules) obeys well defined propensity rules based on the molecular symmetry and on the topology of the molecule in the junction. Focusing on conjugated molecules of C(2h) symmetry, semiquantitative arguments suggest that the IETS is dominated by a(g) vibrations in the high energy region and by out of plane modes (a(u) and b(g)) in the low energy region. Realistic computations verify that the proposed propensity rules are strictly obeyed by medium to large-sized conjugated molecules but are subject to some exceptions when small molecules are considered. The propensity rules facilitate the use of IETS to help characterize the molecular geometry within the junction.
Collapse
Affiliation(s)
- Alessandro Troisi
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
| | | |
Collapse
|
45
|
Abstract
We discuss the relationship between the inelastic electron tunneling spectroscopy (IETS) and vibronic coupling constant within the Green's function formalism at a level of perturbation theory approximation. We also compare our results with experimental measurements. Our results can provide insights into the mechanism of active vibronic modes for IETS.
Collapse
Affiliation(s)
- Liuming Yan
- Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, China.
| |
Collapse
|
46
|
Solomon GC, Gagliardi A, Pecchia A, Frauenheim T, Di Carlo A, Reimers JR, Hush NS. The symmetry of single-molecule conduction. J Chem Phys 2006; 125:184702. [PMID: 17115774 DOI: 10.1063/1.2363976] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We introduce the conductance point group which defines the symmetry of single-molecule conduction within the nonequilibrium Green's function formalism. It is shown, either rigorously or to within a very good approximation, to correspond to a molecular-conductance point group defined purely in terms of the properties of the conducting molecule. This enables single-molecule conductivity to be described in terms of key qualitative chemical descriptors that are independent of the nature of the molecule-conductor interfaces. We apply this to demonstrate how symmetry controls the conduction through 1,4-benzenedithiol chemisorbed to gold electrodes as an example system, listing also the molecular-conductance point groups for a range of molecules commonly used in molecular electronics research.
Collapse
Affiliation(s)
- Gemma C Solomon
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | | | | | | | | | | | | |
Collapse
|
47
|
Solomon GC, Gagliardi A, Pecchia A, Frauenheim T, Di Carlo A, Reimers JR, Hush NS. Molecular origins of conduction channels observed in shot-noise measurements. NANO LETTERS 2006; 6:2431-7. [PMID: 17090069 DOI: 10.1021/nl0614516] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Measurements of shot noise from single molecules have indicated the presence of various conduction channels. We present three descriptions of these channels in molecular terms showing that the number of conduction channels is limited by bottlenecks in the molecule and that the channels can be linked to transmission through different junction states. We introduce molecular-conductance orbitals, which allow the transmission to be separated into contributions from individual orbitals and contributions from interference between pairs of orbitals.
Collapse
Affiliation(s)
- Gemma C Solomon
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | | | | | | | | | | | | |
Collapse
|
48
|
Long DP, Lazorcik JL, Mantooth BA, Moore MH, Ratner MA, Troisi A, Yao Y, Ciszek JW, Tour JM, Shashidhar R. Effects of hydration on molecular junction transport. NATURE MATERIALS 2006; 5:901-8. [PMID: 17041584 DOI: 10.1038/nmat1754] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 09/01/2006] [Indexed: 05/09/2023]
Abstract
The study of charge transport through increasingly complex small molecules will benefit from a detailed understanding of how contaminants from the environment affect molecular conduction. This should provide a clearer picture of the electronic characteristics of molecules by eliminating interference from adsorbed species. Here we use magnetically assembled microsphere junctions incorporating thiol monolayers to provide insight into changing electron transport characteristics resulting from exposure to air. Using this technique, current-voltage analysis and inelastic electron tunnelling spectroscopy (IETS) demonstrate that the primary interaction affecting molecular conduction is rapid hydration at the gold-sulphur contacts. We use IETS to present evidence for changing mechanisms of charge transport as a result of this interaction. The detrimental effects on molecular conduction discussed here are important for understanding electron transport through gold-thiol molecular junctions once exposed to atmospheric conditions.
Collapse
Affiliation(s)
- David P Long
- Research and Development Center, Science Applications International Corporation (SAIC), 9460 Innovation Drive, Manassas, Virginia 20110, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Troisi A, Ratner MA. Molecular transport junctions: Propensity rules for inelastic electron tunneling spectra. NANO LETTERS 2006; 6:1784-8. [PMID: 16895374 DOI: 10.1021/nl0609394] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We develop a series of propensity rules for interpreting inelastic electron tunneling (IET) spectra of single-molecule transport junctions. IETS has no selection rules, such as those seen in optical, infrared, and Raman spectra, because IETS features arise not from the field-dipole interaction characterizing these other spectroscopies but from vibronic modification of the electronic levels. Expansion of the Landauer-Imry formula in Taylor series in molecular normal coordinates gives a convenient, accurate perturbation-type formula for calculating both frequency and intensity of the IETS spectrum. Expansion in a Dyson-like form permits derivation of propensity rules, both symmetry-based and pathway-deduced, allowing correlation of structure and coupling geometry with the IETS spectrum. These propensity rules work very well for the calculated spectrum of five typical molecular bridges.
Collapse
Affiliation(s)
- Alessandro Troisi
- Department of Chemistry and Centre of Scientific Computing, University of Warwick, CV4 7AL Coventry, UK
| | | |
Collapse
|
50
|
Kula M, Jiang J, Luo Y. Probing molecule-metal bonding in molecular junctions by inelastic electron tunneling spectroscopy. NANO LETTERS 2006; 6:1693-8. [PMID: 16895358 DOI: 10.1021/nl060951w] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We present first-principles calculations for the inelastic electron tunneling spectra (IETS) of three molecules, 1-undecane thiol (C11), alpha,omega-bis(thioacetyl)oligophenylenethynylene (OPE), and alpha,omega-bis(thioacetyl)oligophenylenevinylene (OPV), sandwiched between two gold electrodes. We have demonstrated that IETS is very sensitive to the bonding between the molecule and electrodes. In comparison with experiment of Kushmerick et al. (Nano Lett. 2004, 4, 639), it has been concluded that the C11 forms a strong chemical bond, while the bonding of the OPE and OPV systems are slightly weaker. All experimental spectral features have been correctly assigned.
Collapse
Affiliation(s)
- Mathias Kula
- Theoretical Chemistry, Royal Institute of Technology, AlbaNova, S-106 91 Stockholm, Sweden
| | | | | |
Collapse
|