Conductance and Vibrational States of Single-Molecule Junctions Controlled by Mechanical Stretching and Material Variation

Kim, Young-Sang; Song, Hyunwook; Strigl, Florian; Pernau, Hans‐Fridtjof; Lee, Takhee; Scheer, Elke

doi:10.1103/physrevlett.106.196804

Cited by 123 publications

(141 citation statements)

References 30 publications

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“…therefore in good agreement with previous results on ADT from the literature [13,[27][28][29][30][31]. With a broadening of V rms = 5 mV one identifies nine main peaks in the energy range above 40 meV as summarized in Table I.…”

Section: Fig 2 (Color Online) Plots Of the K-averaged Transmission supporting

confidence: 80%

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Role ofk-point sampling in the supercell approach to inelastic electron tunneling spectroscopy simulations of molecular monolayers

2015

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While the role of sampling of the electron momentum k in supercell calculations of the elastic electron transmission is well understood, its influence in the case of inelastic electron tunneling (IET) has not yet been systematically explored. Here we compare ab initio IET spectra of molecular monolayers in the commonly used -point approximation to rigorously k-converged results. We study four idealized molecular junctions with either alkanedithiolates or benzenedithiolates, and explore variations due to varying molecular tilt angle, density, as well as chemical identity of the monolayer. We show that the -point approximation is reasonable for a range of systems, but that a rigorous convergence is needed for accurate signal amplitudes. We also describe an approximative scheme which reduces the computational cost of the k-averaged calculation in our implementation.

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Section: Fig 2 (Color Online) Plots Of the K-averaged Transmission supporting

confidence: 80%

“…Alkanedithiolates (ADT) represent a prototype tunnel junction [16][17][18][19][20] and their IETS spectra are among the best characterized [21][22][23][24][25][26][27][28][29][30][31]. From a theoretical point of view they thus provide a good reference for testing new computational strategies.…”

Section: Introductionmentioning

confidence: 99%

Role ofk-point sampling in the supercell approach to inelastic electron tunneling spectroscopy simulations of molecular monolayers

2015

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“…By comparing Tables I and II common modes between IETS and IR spectra can be recognized in the energy range 100 meV < E < 200 meV. In particular, we find common signatures of the =C-H in-plane and outof-plane deformations in the energy range 100-130 meV (890-1050 cm −1 ) [34,35,42,43,[46][47][48], where signatures of the N-H deformation or C-C stretching are also predicted [21,37,42,48,49]. Common signatures of the stretching of different carbon based bonds are also detectable, such as C-N, C=C, and C=O in the energy range 160-210 meV (1290-1690 cm −1 ) [21,35,42,43,[47][48][49].…”

Section: Comparison To Aq Layer Infrared Spectroscopymentioning

confidence: 84%

“…For negative polarity the sign of the d 2 I/dV 2 has been inverted for the sake of clarity. The red line corresponds to data after symmetrization following the simple formula y = [f (x) − f (−x)]/2, and revealing the existence of symmetric peaks [21,37,38]. Note that peak symmetry is less evident at higher energies.…”

Section: Aq Junctions Transport Measurementsmentioning

confidence: 99%

Inelastic electron tunneling spectroscopy in molecular junctions showing quantum interference

et al. 2017

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Destructive quantum interference effect is implemented in large area molecular junctions to improve signatures of electron-phonon interaction. Vertical molecular junctions based on a cross-conjugated anthraquinone layer were fabricated and low-noise transport measurements were performed by acquiring simultaneously the current-voltage characteristics, its second derivative, and the differential conductance. Signatures of vibrational modes excited by inelastic events are present in the whole measured voltage range and superpose to the conductance suppression induced by destructive quantum interference. As a consequence vibrational modes have improved visibility in the low energy window (<80 meV). Inelastic electron transport spectroscopy data are compared to infrared attenuated total reflection spectroscopy on Au/anthraquinone thin films. Common vibrational modes can be clearly identified, but inelastic electron tunneling spectroscopy reveals the existence of vibrational modes in a wider energy range (0-400 meV) where infrared spectroscopy is lacking.

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“…Hence, distinguishing the dominant trend in single-molecule junctions requires the combination of an adjustable electrode separation with an electrostatic gate. Although mechanical control over molecular conductance has been reported in various studies 7,10,[18][19][20][21][22][23] , in only very few reports it has been combined with an electrostatic gate 18,19 . In particular, systematic studies based on explicit monitoring …”

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confidence: 99%

Large tunable image-charge effects in single-molecule junctions

et al. 2013

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The characteristics of molecular electronic devices are critically determined by metal-organic interfaces, which influence the arrangement of the orbital levels that participate in charge transport.Studies on self-assembled monolayers (SAMs) show (molecule-dependent) level shifts as well as transport-gap renormalization, suggesting that polarization effects in the metal substrate play a key role in the level alignment with respect to the metal's Fermi energy. Here, we provide direct evidence for an electrode-induced gap renormalization in single-molecule junctions. We study charge transport in single porphyrin-type molecules using electrically gateable break junctions.In this set-up, the position of the occupied and unoccupied levels can be followed in situ and with simultaneous mechanical control. When increasing the electrode separation, we observe a substantial increase in the transport gap with level shifts as high as several hundreds of meV for displacements of a fewÅngstroms. Analysis of this large and tunable gap renormalization with image-charge calculations based on atomic charges obtained from density functional theory confirms and clarifies the dominant role of image-charge effects in single-molecule junctions.

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Conductance and Vibrational States of Single-Molecule Junctions Controlled by Mechanical Stretching and Material Variation

Cited by 123 publications

References 30 publications

Role ofk-point sampling in the supercell approach to inelastic electron tunneling spectroscopy simulations of molecular monolayers

Role ofk-point sampling in the supercell approach to inelastic electron tunneling spectroscopy simulations of molecular monolayers

Inelastic electron tunneling spectroscopy in molecular junctions showing quantum interference

Large tunable image-charge effects in single-molecule junctions

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