Identification of vibration modes in single-molecule junctions by strong inelastic signals in noise

We study single-molecule oligo(phenylene ethynylene)dithiol junctions by means of inelastic electron tunneling spectroscopy (IETS). The molecule is contacted with gold nano-electrodes formed with the mechanically controllable break junction technique. We record the IETS spectrum of the molecule from direct current measurements, both as a function of time and electrode separation. We find that for fixed electrode separation the molecule switches between various configurations, which are characterized by different IETS spectra. Similar variations in the IETS signal are observed during atomic rearrangements upon stretching of the molecular junction. Using quantum chemistry calculations, we identity some of the vibrational modes which constitute a chemical fingerprint of the molecule. In addition, changes can be attributed to rearrangements of the local molecular environment, in particular at the molecule–electrode interface. This study shows the importance of taking into account the interaction with the electrodes when describing inelastic contributions to transport through single-molecule junctions.

Download Full-text

Line shapes in inelastic electron tunneling spectroscopy of single-molecule junctions

Physical Review B ◽

10.1103/physrevb.96.205437 ◽

2017 ◽

Vol 96 (20) ◽

Cited By ~ 4

Author(s):

S. Meierott ◽

N. Néel ◽

J. Kröger

Keyword(s):

Single Molecule ◽

Electron Tunneling ◽

Tunneling Spectroscopy ◽

Inelastic Electron ◽

Inelastic Electron Tunneling Spectroscopy ◽

Line Shapes ◽

Single Molecule Junctions ◽

Inelastic Electron Tunneling ◽

Electron Tunneling Spectroscopy

Download Full-text

Inelastic electron tunneling spectroscopy of difurylethene-based photochromic single-molecule junctions

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.8.261 ◽

2017 ◽

Vol 8 ◽

pp. 2606-2614 ◽

Cited By ~ 1

Author(s):

Youngsang Kim ◽

Safa G Bahoosh ◽

Dmytro Sysoiev ◽

Thomas Huhn ◽

Fabian Pauly ◽

...

Keyword(s):

Single Molecule ◽

Electron Tunneling ◽

Electrical Conductance ◽

Inelastic Electron ◽

First Principles Calculations ◽

Inelastic Electron Tunneling Spectroscopy ◽

Single Molecule Junctions ◽

Inelastic Electron Tunneling ◽

Electron Tunneling Spectroscopy ◽

Vibrational Features

Diarylethene-derived molecules alter their electronic structure upon transformation between the open and closed forms of the diarylethene core, when exposed to ultraviolet (UV) or visible light. This transformation results in a significant variation of electrical conductance and vibrational properties of corresponding molecular junctions. We report here a combined experimental and theoretical analysis of charge transport through diarylethene-derived single-molecule devices, which are created using the mechanically controlled break-junction technique. Inelastic electron tunneling (IET) spectroscopy measurements performed at 4.2 K are compared with first-principles calculations in the two distinct forms of diarylethenes connected to gold electrodes. The combined approach clearly demonstrates that the IET spectra of single-molecule junctions show specific vibrational features that can be used to identify different isomeric molecular states by transport experiments.

Download Full-text

Shot Noise of 1,4-Benzenedithiol Single-Molecule Junctions

Nano Letters ◽

10.1021/acs.nanolett.5b04848 ◽

2016 ◽

Vol 16 (3) ◽

pp. 1803-1807 ◽

Cited By ~ 26

Author(s):

M. A. Karimi ◽

S. G. Bahoosh ◽

M. Herz ◽

R. Hayakawa ◽

F. Pauly ◽

...

Keyword(s):

Single Molecule ◽

Shot Noise ◽

Single Molecule Junctions

Download Full-text

Characteristics of Amine-Ended and Thiol-Ended Alkane Single-Molecule Junctions Revealed by Inelastic Electron Tunneling Spectroscopy

ACS Nano ◽

10.1021/nn200759s ◽

2011 ◽

Vol 5 (5) ◽

pp. 4104-4111 ◽

Cited By ~ 76

Author(s):

Youngsang Kim ◽

Thomas Julian Hellmuth ◽

Marius Bürkle ◽

Fabian Pauly ◽

Elke Scheer

Keyword(s):

Single Molecule ◽

Electron Tunneling ◽

Tunneling Spectroscopy ◽

Inelastic Electron ◽

Inelastic Electron Tunneling Spectroscopy ◽

Single Molecule Junctions ◽

Inelastic Electron Tunneling ◽

Electron Tunneling Spectroscopy

Download Full-text

Electronic conduction during the formation stages of a single-molecule junction

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.9.138 ◽

2018 ◽

Vol 9 ◽

pp. 1471-1477 ◽

Cited By ~ 3

Author(s):

Atindra Nath Pal ◽

Tal Klein ◽

Ayelet Vilan ◽

Oren Tal

Keyword(s):

Single Molecule ◽

Electronic Transport ◽

Noise Analysis ◽

Atomic Scale ◽

Single Atom ◽

Inelastic Electron ◽

Single Molecule Junctions ◽

Molecule Junction ◽

Single Molecule Junction ◽

Silver Electrodes

Single-molecule junctions are versatile test beds for electronic transport at the atomic scale. However, not much is known about the early formation steps of such junctions. Here, we study the electronic transport properties of premature junction configurations before the realization of a single-molecule bridge based on vanadocene molecules and silver electrodes. With the aid of conductance measurements, inelastic electron spectroscopy and shot noise analysis, we identify the formation of a single-molecule junction in parallel to a single-atom junction and examine the interplay between these two conductance pathways. Furthermore, the role of this structure in the formation of single-molecule junctions is studied. Our findings reveal the conductance and structural properties of premature molecular junction configurations and uncover the different scenarios in which a single-molecule junction is formed. Future control over such processes may pave the way for directed formation of preferred junction structures.

Download Full-text

Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions

10.26434/chemrxiv.12252059 ◽

2020 ◽

Author(s):

María Camarasa-Gómez ◽

Daniel Hernangómez-Pérez ◽

Michael S. Inkpen ◽

Giacomo Lovat ◽

E-Dean Fung ◽

...

Keyword(s):

Single Molecule ◽

Quantum Interference ◽

Degrees Of Freedom ◽

Building Blocks ◽

Ferrocene Derivative ◽

Single Molecule Junctions ◽

Molecule Junction ◽

Single Molecule Junction ◽

The Impact ◽

D Orbitals

Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted some interest as functional elements of molecular-scale devices. Here we investigate the impact of the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction conductance. Measurements indicate that the conductance of the ferrocene derivative, which is suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.

Download Full-text

Charge Transfer Complexation Boosts Molecular Conductance Through Fermi Level Pinning

10.26434/chemrxiv.7110788 ◽

2018 ◽

Author(s):

Kun Wang ◽

Andrea Vezzoli ◽

Iain Grace ◽

Maeve McLaughlin ◽

Richard Nichols ◽

...

Keyword(s):

Charge Transfer ◽

Single Molecule ◽

Quantum Interference ◽

Transmission Function ◽

Scanning Tunneling ◽

Charge Transfer Complexes ◽

Tunneling Microscopy ◽

Quantum Interference Effect ◽

Single Molecule Junctions ◽

Charge Transfer Complexation

We have used scanning tunneling microscopy to create and study single molecule junctions with thioether-terminated oligothiophene molecules. We find that the conductance of these junctions increases upon formation of charge transfer complexes of the molecules with tetracyanoethene, and that the extent of the conductance increase is greater the longer is the oligothiophene, i.e. the lower is the conductance of the uncomplexed molecule in the junction. We use non-equilibrium Green's function transport calculations to explore the reasons for this theoretically, and find that new resonances appear in the transmission function, pinned close to the Fermi energy of the contacts, as a consequence of the charge transfer interaction. This is an example of a room temperature quantum interference effect, which in this case boosts junction conductance in contrast to earlier observations of QI that result in diminished conductance.

Download Full-text