1
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Yu L, Zhang M, Chen H, Xiao B, Chang S. Measurements of single-molecule electromechanical properties based on atomic force microscopy fixed-junction technique. NANOSCALE 2023; 15:4277-4281. [PMID: 36751974 DOI: 10.1039/d2nr06074d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
A hybrid technique combining atomic force microscopy and the fixed-junction technique is developed to simultaneously probe the electrical and mechanical characteristics of a single-molecule junction.
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Affiliation(s)
- Lei Yu
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China.
- The Institute of Advanced Materials and Nanotechnology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China
| | - Mingyang Zhang
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China.
- The Institute of Advanced Materials and Nanotechnology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China
| | - Haijian Chen
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China.
- The Institute of Advanced Materials and Nanotechnology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China
| | - Bohuai Xiao
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China.
- The Institute of Advanced Materials and Nanotechnology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China
| | - Shuai Chang
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China.
- The Institute of Advanced Materials and Nanotechnology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, China
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2
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Zhu Y, Tan Z, Hong W. Simultaneous Electrical and Mechanical Characterization of Single-Molecule Junctions Using AFM-BJ Technique. ACS OMEGA 2021; 6:30873-30888. [PMID: 34841131 PMCID: PMC8613807 DOI: 10.1021/acsomega.1c04785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/29/2021] [Indexed: 06/13/2023]
Abstract
The fabrication and characterization of single-molecule junctions provide a unique platform to study the physical phenomena of a single molecule, and the electrical characterization enables us to understand the electrical transport properties of a single molecule and guide the fabrication of molecular electronic devices. However, the electrical characterization of single-molecule junctions is sometimes insufficient to extract the structural information on single-molecule junctions, and an alternate method to address this problem is to characterize the mechanical properties of single-molecule junctions. Simultaneous measurement of mechanical and electrical properties can provide complementary information on single molecules to analyze the correlations of their electrical and mechanical properties in the evolution of single-molecule junctions. In this mini-review, we summarize the progress on the simultaneous characterizations of mechanical and electrical properties for single-molecule junctions, and discuss the challenges and perspectives of this research area.
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3
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Mezei G, Balogh Z, Magyarkuti A, Halbritter A. Voltage-Controlled Binary Conductance Switching in Gold-4,4'-Bipyridine-Gold Single-Molecule Nanowires. J Phys Chem Lett 2020; 11:8053-8059. [PMID: 32893638 PMCID: PMC7528405 DOI: 10.1021/acs.jpclett.0c02185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We investigate gold-4,4'-bipyridine-gold single-molecule junctions with the mechanically controllable break junction technique at cryogenic temperature (T = 4.2 K). We observe bistable probabilistic conductance switching between the two molecular binding configurations, influenced both by the mechanical actuation and by the applied voltage. We demonstrate that the relative dominance of the two conductance states is tunable by the electrode displacement, whereas the voltage manipulation induces an exponential speedup of both switching times. The detailed investigation of the voltage-tunable switching rates provides an insight into the possible switching mechanisms.
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Affiliation(s)
- G. Mezei
- Department
of Physics, Budapest University of Technology
and Economics, 1111 Budapest, Budafoki ut 8., Hungary
- MTA-BME
Condensed Matter Research Group, Budafoki
ut 8, 1111 Budapest, Hungary
| | - Z. Balogh
- Department
of Physics, Budapest University of Technology
and Economics, 1111 Budapest, Budafoki ut 8., Hungary
- MTA-BME
Condensed Matter Research Group, Budafoki
ut 8, 1111 Budapest, Hungary
| | - A. Magyarkuti
- Department
of Physics, Budapest University of Technology
and Economics, 1111 Budapest, Budafoki ut 8., Hungary
- MTA-BME
Condensed Matter Research Group, Budafoki
ut 8, 1111 Budapest, Hungary
| | - A. Halbritter
- Department
of Physics, Budapest University of Technology
and Economics, 1111 Budapest, Budafoki ut 8., Hungary
- MTA-BME
Condensed Matter Research Group, Budafoki
ut 8, 1111 Budapest, Hungary
- E-mail:
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4
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Lauritzen KP, Magyarkuti A, Balogh Z, Halbritter A, Solomon GC. Classification of conductance traces with recurrent neural networks. J Chem Phys 2018; 148:084111. [PMID: 29495782 DOI: 10.1063/1.5012514] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a new automated method for structural classification of the traces obtained in break junction experiments. Using recurrent neural networks trained on the traces of minimal cross-sectional area in molecular dynamics simulations, we successfully separate the traces into two classes: point contact or nanowire. This is done without any assumptions about the expected features of each class. The trained neural network is applied to experimental break junction conductance traces, and it separates the classes as well as the previously used experimental methods. The effect of using partial conductance traces is explored, and we show that the method performs equally well using full or partial traces (as long as the trace just prior to breaking is included). When only the initial part of the trace is included, the results are still better than random chance. Finally, we show that the neural network classification method can be used to classify experimental conductance traces without using simulated results for training, but instead training the network on a few representative experimental traces. This offers a tool to recognize some characteristic motifs of the traces, which can be hard to find by simple data selection algorithms.
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Affiliation(s)
- Kasper P Lauritzen
- Nano-Science Center and Department of Chemistry, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - András Magyarkuti
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Condensed Matter Research Group, Budafoki ut 8, 1111 Budapest, Hungary
| | - Zoltán Balogh
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Condensed Matter Research Group, Budafoki ut 8, 1111 Budapest, Hungary
| | - András Halbritter
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Condensed Matter Research Group, Budafoki ut 8, 1111 Budapest, Hungary
| | - Gemma C Solomon
- Nano-Science Center and Department of Chemistry, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
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5
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Moreno Ostertag L, Utzig T, Klinger C, Valtiner M. Tether-Length Dependence of Bias in Equilibrium Free-Energy Estimates for Surface-to-Molecule Unbinding Experiments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:766-772. [PMID: 29087720 PMCID: PMC6398919 DOI: 10.1021/acs.langmuir.7b02844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/30/2017] [Indexed: 06/07/2023]
Abstract
The capabilities of atomic force microscopes and optical tweezers to probe unfolding or surface-to-molecule bond rupture at a single-molecular level are widely appreciated. These measurements are typically carried out unidirectionally under nonequilibrium conditions. Jarzynski's equality has proven useful to relate the work obtained along these nonequilibrium trajectories to the underlying free energy of the unfolding or unbinding process. Here, we quantify biases that arise from the molecular design of the bond rupture experiment for probing surface-to-molecule bonds. In particular, we probe the well-studied amine/gold bond as a function of the linker's length which is used to anchor the specific amine functionality during a single molecule unbinding experiment. With increasing linker length, we observe a significant increase in the average work spent on polymer stretching and a strongly biased estimated interaction free energy. Our data demonstrate that free energy estimates converge well for linker lengths below 20 nm, where the bias is <10-15%. With longer linkers severe methodical limits of the method are reached, and convergence within a reasonable number of realizations of the bond rupture is not feasible. Our results also provide new insights into stability and work dissipation mechanisms at adhesive interfaces at the single-molecular level, and offer important design and analysis aspects for single-molecular surface-to-molecule experiments.
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Affiliation(s)
- Laila Moreno Ostertag
- Interaction
Forces and Functional Materials, Department of Interface Chemistry
and Surface Engineering, Max-Planck-Institut
für Eisenforschung GmbH, 40237 Düsseldorf, Germany
| | - Thomas Utzig
- Interaction
Forces and Functional Materials, Department of Interface Chemistry
and Surface Engineering, Max-Planck-Institut
für Eisenforschung GmbH, 40237 Düsseldorf, Germany
| | - Christine Klinger
- Institut
für Physikalische Chemie II, TU Bergakademie
Freiberg, 09599 Freiberg, Germany
| | - Markus Valtiner
- Interaction
Forces and Functional Materials, Department of Interface Chemistry
and Surface Engineering, Max-Planck-Institut
für Eisenforschung GmbH, 40237 Düsseldorf, Germany
- Institute
for Applied Physics, Applied Interface Physics, Technical University of Vienna, 1040 Vienna, Austria
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6
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Wang M, Wang Y, Sanvito S, Hou S. The low-bias conducting mechanism of single-molecule junctions constructed with methylsulfide linker groups and gold electrodes. J Chem Phys 2017; 147:054702. [PMID: 28789544 DOI: 10.1063/1.4996745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Minglang Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
| | - Yongfeng Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
- Beida Information Research (BIR), Tianjin 300457, China
| | - Stefano Sanvito
- School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
| | - Shimin Hou
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China
- Beida Information Research (BIR), Tianjin 300457, China
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7
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Hybertsen MS. Modeling single molecule junction mechanics as a probe of interface bonding. J Chem Phys 2017. [DOI: 10.1063/1.4975769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mark S. Hybertsen
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
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8
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Wang L, Gong ZL, Li SY, Hong W, Zhong YW, Wang D, Wan LJ. Molecular Conductance through a Quadruple-Hydrogen-Bond-Bridged Supramolecular Junction. Angew Chem Int Ed Engl 2016; 55:12393-7. [PMID: 27576570 DOI: 10.1002/anie.201605622] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Indexed: 11/06/2022]
Abstract
A series of self-complementary ureido pyrimidinedione (UPy) derivatives modified with different aurophilic anchoring groups were synthesized. Their electron transport properties through the quadruple hydrogen bonds in apolar solvent were probed employing the scanning tunneling microscopy break junction (STMBJ) technique. The molecule terminated with a thiol shows the optimal electron transport properties, with a statistical conductance value that approaches 10(-3) G0 . The (1) H NMR spectra and control experiments verify the formation of quadruple hydrogen bonds, which can be effectively modulated by the polarity of the solvent environment. These findings provide a new design strategy for supramolecular circuit elements in molecular electronics.
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Affiliation(s)
- Lin Wang
- Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P.R. China.,University of the Chinese Academy of Sciences, Beijing, 100049, P.R. China.,Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Zhong-Liang Gong
- CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences and, Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P.R. China.,University of the Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Shu-Ying Li
- Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P.R. China.,University of the Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Wenjing Hong
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland. .,Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P.R. China.
| | - Yu-Wu Zhong
- CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences and, Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P.R. China. .,University of the Chinese Academy of Sciences, Beijing, 100049, P.R. China.
| | - Dong Wang
- Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P.R. China. .,University of the Chinese Academy of Sciences, Beijing, 100049, P.R. China.
| | - Li-Jun Wan
- Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences, Beijing, 100190, P.R. China.,University of the Chinese Academy of Sciences, Beijing, 100049, P.R. China
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9
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Wang L, Gong ZL, Li SY, Hong W, Zhong YW, Wang D, Wan LJ. Molecular Conductance through a Quadruple-Hydrogen-Bond-Bridged Supramolecular Junction. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201605622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Lin Wang
- Key Laboratory of Molecular Nanostructure and Nanotechnology; Institute of Chemistry; Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences; Beijing 100190 P.R. China
- University of the Chinese Academy of Sciences; Beijing 100049 P.R. China
- Department of Chemistry and Biochemistry; University of Bern; Freiestrasse 3 3012 Bern Switzerland
| | - Zhong-Liang Gong
- CAS Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences and; Beijing National Laboratory for Molecular Sciences; Beijing 100190 P.R. China
- University of the Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Shu-Ying Li
- Key Laboratory of Molecular Nanostructure and Nanotechnology; Institute of Chemistry; Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences; Beijing 100190 P.R. China
- University of the Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Wenjing Hong
- Department of Chemistry and Biochemistry; University of Bern; Freiestrasse 3 3012 Bern Switzerland
- Department of Chemical and Biochemical Engineering; College of Chemistry and Chemical Engineering; Xiamen University; Xiamen 361005 P.R. China
| | - Yu-Wu Zhong
- CAS Key Laboratory of Photochemistry; Institute of Chemistry; Chinese Academy of Sciences and; Beijing National Laboratory for Molecular Sciences; Beijing 100190 P.R. China
- University of the Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Dong Wang
- Key Laboratory of Molecular Nanostructure and Nanotechnology; Institute of Chemistry; Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences; Beijing 100190 P.R. China
- University of the Chinese Academy of Sciences; Beijing 100049 P.R. China
| | - Li-Jun Wan
- Key Laboratory of Molecular Nanostructure and Nanotechnology; Institute of Chemistry; Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences; Beijing 100190 P.R. China
- University of the Chinese Academy of Sciences; Beijing 100049 P.R. China
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10
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Hybertsen MS, Venkataraman L. Structure-Property Relationships in Atomic-Scale Junctions: Histograms and Beyond. Acc Chem Res 2016; 49:452-60. [PMID: 26938931 DOI: 10.1021/acs.accounts.6b00004] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Over the past 10 years, there has been tremendous progress in the measurement, modeling and understanding of structure-function relationships in single molecule junctions. Numerous research groups have addressed significant scientific questions, directed both to conductance phenomena at the single molecule level and to the fundamental chemistry that controls junction functionality. Many different functionalities have been demonstrated, including single-molecule diodes, optically and mechanically activated switches, and, significantly, physical phenomena with no classical analogues, such as those based on quantum interference effects. Experimental techniques for reliable and reproducible single molecule junction formation and characterization have led to this progress. In particular, the scanning tunneling microscope based break-junction (STM-BJ) technique has enabled rapid, sequential measurement of large numbers of nanoscale junctions allowing a statistical analysis to readily distinguish reproducible characteristics. Harnessing fundamental link chemistry has provided the necessary chemical control over junction formation, enabling measurements that revealed clear relationships between molecular structure and conductance characteristics. Such link groups (amines, methylsuflides, pyridines, etc.) maintain a stable lone pair configuration that selectively bonds to specific, undercoordinated transition metal atoms available following rupture of a metal point contact in the STM-BJ experiments. This basic chemical principle rationalizes the observation of highly reproducible conductance signatures. Subsequently, the method has been extended to probe a variety of physical phenomena ranging from basic I-V characteristics to more complex properties such as thermopower and electrochemical response. By adapting the technique to a conducting cantilever atomic force microscope (AFM-BJ), simultaneous measurement of the mechanical characteristics of nanoscale junctions as they are pulled apart has given complementary information such as the stiffness and rupture force of the molecule-metal link bond. Overall, while the BJ technique does not produce a single molecule circuit for practical applications, it has proved remarkably versatile for fundamental studies. Measured data and analysis have been combined with atomic-scale theory and calculations, typically performed for representative junction structures, to provide fundamental physical understanding of structure-function relationships. This Account integrates across an extensive series of our specific nanoscale junction studies which were carried out with the STM- and AFM-BJ techniques and supported by theoretical analysis and density functional theory based calculations, with emphasis on the physical characteristics of the measurement process and the rich data sets that emerge. Several examples illustrate the impact of measured trends based on the most probable values for key characteristics (obtained from ensembles of order 1000-10 000 individual junctions) to build a solid picture of conductance phenomena as well as attributes of the link bond chemistry. The key forward-looking question posed here is the extent to which the full data sets represented by the individual trajectories can be analyzed to address structure-function questions at the level of individual junctions. Initial progress toward physical modeling of conductance of individual junctions indicates trends consistent with physical junction structures. Analysis of junction mechanics reveals a scaling procedure that collapses existing data onto a universal force-extension curve. This research directed to understanding the distribution of structures and physical characteristics addresses fundamental questions concerning the interplay between chemical control and stochastically driven diversity.
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Affiliation(s)
- Mark S. Hybertsen
- Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Latha Venkataraman
- Department
of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
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11
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Utzig T, Raman S, Valtiner M. Scaling from single molecule to macroscopic adhesion at polymer/metal interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2722-2729. [PMID: 25668596 DOI: 10.1021/la504542f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding the evolution of macroscopic adhesion based on fundamental molecular interactions is crucial to designing strong and smart polymer/metal interfaces that play an important role in many industrial and biomedical applications. Here we show how macroscopic adhesion can be predicted on the basis of single molecular interactions. In particular, we carry out dynamic single molecule-force spectroscopy (SM-AFM) in the framework of Bell-Evans' theory to gain information about the energy barrier between the bound and unbound states of an amine/gold junction. Furthermore, we use Jarzynski's equality to obtain the equilibrium ground-state energy difference of the amine/gold bond from these nonequilibrium force measurements. In addition, we perform surface forces apparatus (SFA) experiments to measure macroscopic adhesion forces at contacts where approximately 10(7) amine/gold bonds are formed simultaneously. The SFA approach provides an amine/gold interaction energy (normalized by the number of interacting molecules) of (36 ± 1)k(B)T, which is in excellent agreement with the interaction free energy of (35 ± 3)k(B)T calculated using Jarzynski's equality and single-molecule AFM experiments. Our results validate Jarzynski's equality for the field of polymer/metal interactions by measuring both sides of the equation. Furthermore, the comparison of SFA and AFM shows how macroscopic interaction energies can be predicted on the basis of single molecular interactions, providing a new strategy to potentially predict adhesive properties of novel glues or coatings as well as bio- and wet adhesion.
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Affiliation(s)
- Thomas Utzig
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck Straße 1, 40237 Düsseldorf, Germany
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12
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Frisenda R, Tarkuç S, Galán E, Perrin ML, Eelkema R, Grozema FC, van der Zant HSJ. Electrical properties and mechanical stability of anchoring groups for single-molecule electronics. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1558-67. [PMID: 26425407 PMCID: PMC4578406 DOI: 10.3762/bjnano.6.159] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/29/2015] [Indexed: 05/04/2023]
Abstract
We report on an experimental investigation of transport through single molecules, trapped between two gold nano-electrodes fabricated with the mechanically controlled break junction (MCBJ) technique. The four molecules studied share the same core structure, namely oligo(phenylene ethynylene) (OPE3), while having different aurophilic anchoring groups: thiol (SAc), methyl sulfide (SMe), pyridyl (Py) and amine (NH2). The focus of this paper is on the combined characterization of the electrical and mechanical properties determined by the anchoring groups. From conductance histograms we find that thiol anchored molecules provide the highest conductance; a single-level model fit to current-voltage characteristics suggests that SAc groups exhibit a higher electronic coupling to the electrodes, together with better level alignment than the other three groups. An analysis of the mechanical stability, recording the lifetime in a self-breaking method, shows that Py and SAc yield the most stable junctions while SMe form short-lived junctions. Density functional theory combined with non-equlibrium Green's function calculations help in elucidating the experimental findings.
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Affiliation(s)
- Riccardo Frisenda
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Simge Tarkuç
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
- Current address: Arcelik A.S.Central R&D Department, 34950 Tuzla/Istanbul, Turkey
| | - Elena Galán
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Mickael L Perrin
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Rienk Eelkema
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Ferdinand C Grozema
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Herre S J van der Zant
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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