Effect of intermolecular distance and contact hollow-type on the transport properties of parallel atomic wires

Wang, Lihua; Guo, Yong; Zhu, Chao; Tian, Cuifeng; Song, Xiaoping; Ding, Bingjun

doi:10.1016/j.physleta.2009.11.080

Cited by 17 publications

(11 citation statements)

References 29 publications

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“…This means that the molecules in these systems are behaving as nearly independent parallel quantum conductors in a way reminiscent of parallel semiconductor quantum wires [109] connecting a pair of electron reservoirs. Similar, roughly additive, behavior of the low bias conductances of other molecules bridging pairs of metal electrodes in parallel has also been found in previous theoretical studies, for not too small intermolecular separations [110][111][112][113][114][115][116][117][118].…”

Section: Gauche Molecular Conformationssupporting

confidence: 87%

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Identification of the atomic scale structures of the gold-thiol interfaces of molecular nanowires by inelastic tunneling spectroscopy

Demir

Kirczenow

2012

The Journal of Chemical Physics

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We examine theoretically the effects of the bonding geometries at the gold-thiol interfaces on the inelastic tunneling spectra of propanedithiolate (PDT) molecules bridging gold electrodes and show that inelastic tunneling spectroscopy combined with theory can be used to determine these bonding geometries experimentally. With the help of density functional theory, we calculate the relaxed geometries and vibrational modes of extended molecules each consisting of one or two PDT molecules connecting two gold nanoclusters. We formulate a perturbative theory of inelastic tunneling through molecules bridging metal contacts in terms of elastic transmission amplitudes, and use this theory to calculate the inelastic tunneling spectra of the gold-PDT-gold extended molecules. We consider PDT molecules with both trans and gauche conformations bound to the gold clusters at top, bridge, and hollow bonding sites. Comparing our results with the experimental data of Hihath et al. [Nano Lett. 8, 1673 (2008)], we identify the most frequently realized conformation in the experiment as that of trans molecules top-site bonded to both electrodes. We find the switching from the 42 meV vibrational mode to the 46 meV mode observed in the experiment to be due to the transition of trans molecules from mixed top-bridge to pure top-site bonding geometries. Our results also indicate that gauche molecular conformations and hollow site bonding did not contribute significantly to the experimental inelastic tunneling spectra. For pairs of PDT molecules connecting the gold electrodes in parallel we find total elastic conductances close to twice those of single molecules bridging the contacts with similar bonding conformations and small splittings of the vibrational mode energies for the modes that are the most sensitive to the molecule-electrode bonding geometries.

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Section: Gauche Molecular Conformationssupporting

confidence: 87%

“…5(a)-I. As expected based on previous studies [110][111][112][113][114][115][116][117][118], the calculated low bias conductances of these systems differed more from twice the conductance of a single molecule connecting the gold clusters than was the case for the more widely spaced molecules in Fig. 5(a).…”

Section: Gauche Molecular Conformationssupporting

confidence: 80%

Identification of the atomic scale structures of the gold-thiol interfaces of molecular nanowires by inelastic tunneling spectroscopy

Demir

Kirczenow

2012

The Journal of Chemical Physics

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“…However, fewer studies have investigated the I-V characteristics of molecular junction Ag-C 60 -Ag as well as the influence of external conditions on electronic transport properties, which is one of the major themes in molecular electronics and can give important information for the potential applications of devices based on molecular systems. It is known that electronic transport properties of molecular devices are determined not only by the properties of the molecules themselves but also the distance between the molecule and the electrodes [16,17], temperature [18], geometry of the contacts [19,20], quantum interference [21], the size of the electrodes [22], etc. However, the factors that control the electronic transport of C 60 molecular devices have not been well understood.…”

Section: Introductionmentioning

confidence: 99%

The electronic transport properties in C60 molecular devices with different contact distances

Zhai

Fang

et al. 2011

Physics Letters A

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“…In the majority of cases the calculated zero bias conductance values in Table I for molecular junctions with pairs of molecules bridging the gold contacts in parallel are roughly a factor of 2 larger than the conductances of the corresponding single molecule junctions, as might be expected for pairs of molecules [78,[98][99][100][101][102][103][104][105][106] or other quantum conductors [107] connecting electron reservoirs. An exception is the structure in Fig.…”

Section: B Elastic Conductances In the Limit Of Low Biasmentioning

confidence: 72%

Inelastic tunneling spectroscopy of gold-thiol and gold-thiolate interfaces in molecular junctions: The role of hydrogen

Demir

Kirczenow

2012

The Journal of Chemical Physics

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It is widely believed that when a molecule with thiol (S-H) end groups bridges a pair of gold electrodes, the S atoms bond to the gold and the thiol H atoms detach from the molecule. However, little is known regarding the details of this process, its time scale, and whether molecules with and without thiol hydrogen atoms can coexist in molecular junctions. Here we explore theoretically how inelastic tunneling spectroscopy (IETS) can shed light on these issues. We present calculations of the geometries, low bias conductances and IETS of propanedithiol and propanedithiolate molecular junctions with gold electrodes. We show that IETS can distinguish between junctions with molecules having no, one or two thiol hydrogen atoms. We find that in most cases the single-molecule junctions in the IETS experiment of Hihath et al. [Nano Lett. 8, 1673(2008] had no thiol H atoms, but that a molecule with a single thiol H atom may have bridged their junction occasionally. We also consider the evolution of the IETS spectrum as a gold STM tip approaches the intact S-H group at the end of a molecule bound at its other end to a second electrode. We predict the frequency of a vibrational mode of the thiol H atom to increase by a factor ∼ 2 as the gap between the tip and molecule narrows. Therefore, IETS should be able to track the approach of the tip towards the thiol group of the molecule and detect the detachment of the thiol H atom from the molecule when it occurs.

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Effect of intermolecular distance and contact hollow-type on the transport properties of parallel atomic wires

Cited by 17 publications

References 29 publications

Identification of the atomic scale structures of the gold-thiol interfaces of molecular nanowires by inelastic tunneling spectroscopy

Identification of the atomic scale structures of the gold-thiol interfaces of molecular nanowires by inelastic tunneling spectroscopy

The electronic transport properties in C60 molecular devices with different contact distances

Inelastic tunneling spectroscopy of gold-thiol and gold-thiolate interfaces in molecular junctions: The role of hydrogen

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