Abstract

The conductance of single alkanedithiols covalently bound to gold electrodes has been studied by statistical analysis of repeatedly created molecular junctions. For each molecule, the conductance histogram reveals two sets of well-defined peaks, corresponding to two different conductance values. We have found that (1) both conductance values decrease exponentially with the molecular length with an identical decay constant, β ≈ 0.84 Å-1, but with a factor of 5 difference in the prefactor of the exponential function, (2) The current-voltage curves of the two sets can be fit with the Simmons tunneling model, (3) Both conductance values are independent of temperature (between -5 and 60 °C) and the solvent, (4) Despite the difference in the conductance, the forces required to break the molecular junctions are the same, 1,5 nN, These observations lead us to believe that the conduction mechanism in alkanedithiols is due to electron tunneling or superexchange via the bonds along the molecules, and the two sets of conductance peaks are due to two different microscopic configurations of the molecule-electrode contacts.

Original languageEnglish (US)
Pages (from-to)2135-2141
Number of pages7
JournalJournal of the American Chemical Society
Volume128
Issue number6
DOIs
StatePublished - Feb 15 2006

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Electrodes
Molecules
Gold
Electron tunneling
Exponential functions
Electrons
Temperature
Statistical methods
Electric potential

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Conductance of single alkanedithiols : Conduction mechanism and effect of molecule-electrode contacts. / Li, Xiulan; He, Jin; Hihath, Joshua; Xu, Bingqian; Lindsay, Stuart; Tao, Nongjian.

In: Journal of the American Chemical Society, Vol. 128, No. 6, 15.02.2006, p. 2135-2141.

Research output: Contribution to journalArticle

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title = "Conductance of single alkanedithiols: Conduction mechanism and effect of molecule-electrode contacts",
abstract = "The conductance of single alkanedithiols covalently bound to gold electrodes has been studied by statistical analysis of repeatedly created molecular junctions. For each molecule, the conductance histogram reveals two sets of well-defined peaks, corresponding to two different conductance values. We have found that (1) both conductance values decrease exponentially with the molecular length with an identical decay constant, β ≈ 0.84 {\AA}-1, but with a factor of 5 difference in the prefactor of the exponential function, (2) The current-voltage curves of the two sets can be fit with the Simmons tunneling model, (3) Both conductance values are independent of temperature (between -5 and 60 °C) and the solvent, (4) Despite the difference in the conductance, the forces required to break the molecular junctions are the same, 1,5 nN, These observations lead us to believe that the conduction mechanism in alkanedithiols is due to electron tunneling or superexchange via the bonds along the molecules, and the two sets of conductance peaks are due to two different microscopic configurations of the molecule-electrode contacts.",
author = "Xiulan Li and Jin He and Joshua Hihath and Bingqian Xu and Stuart Lindsay and Nongjian Tao",
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T1 - Conductance of single alkanedithiols

T2 - Conduction mechanism and effect of molecule-electrode contacts

AU - Li, Xiulan

AU - He, Jin

AU - Hihath, Joshua

AU - Xu, Bingqian

AU - Lindsay, Stuart

AU - Tao, Nongjian

PY - 2006/2/15

Y1 - 2006/2/15

N2 - The conductance of single alkanedithiols covalently bound to gold electrodes has been studied by statistical analysis of repeatedly created molecular junctions. For each molecule, the conductance histogram reveals two sets of well-defined peaks, corresponding to two different conductance values. We have found that (1) both conductance values decrease exponentially with the molecular length with an identical decay constant, β ≈ 0.84 Å-1, but with a factor of 5 difference in the prefactor of the exponential function, (2) The current-voltage curves of the two sets can be fit with the Simmons tunneling model, (3) Both conductance values are independent of temperature (between -5 and 60 °C) and the solvent, (4) Despite the difference in the conductance, the forces required to break the molecular junctions are the same, 1,5 nN, These observations lead us to believe that the conduction mechanism in alkanedithiols is due to electron tunneling or superexchange via the bonds along the molecules, and the two sets of conductance peaks are due to two different microscopic configurations of the molecule-electrode contacts.

AB - The conductance of single alkanedithiols covalently bound to gold electrodes has been studied by statistical analysis of repeatedly created molecular junctions. For each molecule, the conductance histogram reveals two sets of well-defined peaks, corresponding to two different conductance values. We have found that (1) both conductance values decrease exponentially with the molecular length with an identical decay constant, β ≈ 0.84 Å-1, but with a factor of 5 difference in the prefactor of the exponential function, (2) The current-voltage curves of the two sets can be fit with the Simmons tunneling model, (3) Both conductance values are independent of temperature (between -5 and 60 °C) and the solvent, (4) Despite the difference in the conductance, the forces required to break the molecular junctions are the same, 1,5 nN, These observations lead us to believe that the conduction mechanism in alkanedithiols is due to electron tunneling or superexchange via the bonds along the molecules, and the two sets of conductance peaks are due to two different microscopic configurations of the molecule-electrode contacts.

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