STM Contrast, Electron-Transfer Chemistry, and Conduction in Molecules

Han, Wenhai; Durantini, Edgardo N.; Moore, Thomas A.; Moore, Ana L.; Gust, Devens; Rez, Peter; Leatherman, G.; Seely, G. R.; Tao, Nongjian; Lindsay, Stuart

doi:10.1021/jp972510u

Cited by 137 publications

(120 citation statements)

References 30 publications

(54 reference statements)

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“…Experimental studies of electron tunneling through redox molecules in electrochemical environment were initiated by Tao 14 and comprehensively extended in Refs. [15][16][17][18][19][20]. It was shown in Refs.…”

Section: Introductionmentioning

confidence: 85%

Coulomb repulsion effect in two-electron nonadiabatic tunneling through a one-level redox molecule

Кузнецов¹,

Medvedev²,

Ulstrup³

2009

The Journal of Chemical Physics

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We investigated Coulomb repulsion effects in nonadiabatic ͑diabatic͒ two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact is representative of electrochemical scanning tunneling microscopy or a pair of electrochemical nanoscale electrodes. The two-electron transfer molecular system also represents redox molecules with three electrochemically accessible oxidation states, rather than only two states such as comprehensively studied. It is shown that depending on the effective Coulomb repulsion energy, the current/overpotential relation at fixed bias voltage shows two narrow ͑ϳk B T͒ peaks in the limit of strong electron-phonon coupling to the solvent environment. The system also displays current/bias voltage rectification. The differential conductance/bias voltage correlation can have up to four peaks even for a single-level redox molecule. The peak position, height, and width are determined by the oxidized and reduced states of both the ionization and affinity levels of the molecule and depend crucially on the Debye screening of the electric field in the tunneling gap.

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Section: Introductionmentioning

confidence: 85%

Coulomb repulsion effect in two-electron nonadiabatic tunneling through a one-level redox molecule

Кузнецов¹,

Medvedev²,

Ulstrup³

2009

The Journal of Chemical Physics

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“…4 and from other recent theoretical approaches to molecular conductivity, [20][21][22][23][24][25][26][27][28][29][30][31] but warranted by the recently discovered actual metal/ donor-acceptor-molecule/metal systems. Our approach also rests on recent broader theoretical [32][33][34][35][36] and experimental basis [37][38][39][40][41][42] for scanning tunneling microscopy ͑STM͒ of immobilized redox molecules with low-lying redox levels both in the ex situ, vacuum or air ambient, and in situ electrochemical modes. These disclose in fact close similarities to asymmetric current flow in donor-acceptor molecules.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

Кузнецов

Ulstrup

2002

The Journal of Chemical Physics

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We present a new view and an analytical formalism of electron flow through a donor-acceptor molecule inserted between a pair of metal electrodes. The donor and acceptor levels are strongly coupled to an environmental nuclear continuum. The formalism applies to molecular donoracceptor systems both in vacuum or air, and in aqueous solution under electrochemical potential control. Multifarious patterns of rectified electron flow from the negatively to the positively biased electrode arise. The electronic interaction between the donor and acceptor fragments, mutually and with the electrodes, can be weak, corresponding to the fully diabatic limit. The rectification process then reduces to a sequence of vibrationally relaxed single-electron transfer steps. In the limits where the interactions are strong, denoted as the partially and fully adiabatic limits, the character of the rectification process is different, and electron flow proceeds coherently, without vibrational relaxation. In still another class of mechanisms the electronic level broadening of either donor or acceptor from the adjacent electrode is so strong that it is comparable to the vibrational broadening. The process then reduces to a three-level transition similar to STM of large redox molecules. Recent data for rectification in hexadecyl-quinolinium tricyanodimethanide monolayers by Metzger and co-workers ͓J. Am. Chem. Soc. 119, 10455 ͑1997͒; Acc. Chem. Res. 32, 950 ͑1999͔͒, are discussed in terms of the reported views and formalism.

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“…The electrical current (I) through molecules as a function of applied voltage (V) has been investigated using a scanning tunneling microscope (STM) by setting a metallic tip above a molecular monolayer deposited on a conducting substrate [1,2,3], but the coupling between tip and molecule is often not stable [4,5]. The potential drop through the molecule is much less than that between the STM tip and the bottom electrode.…”

Section: Introductionmentioning

confidence: 99%

Current–voltage characteristics of an LB monolayer of didecylammonium tricyanoquinodimethanide measured between macroscopic gold electrodes

Morris

Szulczewski

et al. 2002

J. Mater. Chem.

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(2002) 'Currentvoltage characteristics of an LB monolayer of didecylammonium tricyanoquinodimethanide measured between macroscopic gold electrodes.', Journal of materials chemistry., 12 (10). pp. 3167-3171. Further information on publisher's website:http://dx.doi.org/10.1039/b203789kPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. monolayer onto a gold surface. Using the "cold-gold" evaporation technique, a set of several macroscopic gold electrode pads were evaporated atop the LB monolayer. Pads which had macroscopic defects were electrical short circuits, but across many pads finite electrical currents were observed as a function of applied bias; however, no obvious electrical rectification was found. The monolayer thickness on a gold substrate measured by XPS to be ~22 Å. Reflection-absorption infrared spectroscopy (RAIRS) indicates that the molecules have a preferred orientation in the film, but are not well ordered. Angleresolved X-ray photoelectron spectroscopy (XPS) suggests that many of the molecules 2 are oriented anti-parallel to each other, possibly because dipole-dipole forces favor such an anti-parallel orientation. This latter observation helps to explain why no electrical rectification was found.

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STM Contrast, Electron-Transfer Chemistry, and Conduction in Molecules

Cited by 137 publications

References 30 publications

Coulomb repulsion effect in two-electron nonadiabatic tunneling through a one-level redox molecule

Coulomb repulsion effect in two-electron nonadiabatic tunneling through a one-level redox molecule

Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

Current–voltage characteristics of an LB monolayer of didecylammonium tricyanoquinodimethanide measured between macroscopic gold electrodes

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