Mediated electron exchange between an electrode and the tip of a scanning tunneling microscope – a stochastic approach

Kuznetsov, An.; Schmickler, Wolfgang

doi:10.1016/s0301-0104(02)00763-2

Cited by 36 publications

(65 citation statements)

References 9 publications

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“…In this limit, the redox center is at the equilibrium potential for ǫ r = λ. As expected, in this case the potential energy surfaces E(q) are similar to the one atom case [57]. At zero bias, they have the same form as for a normal, outer sphere redox reaction-see Fig.…”

Section: Resultssupporting

confidence: 79%

Electron tunneling between two electrodes mediated by a molecular wire containing a redox center

2010

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We derive an explicit expression for the quantum conductivity of a molecular wire containing a redox center, which is embedded in an electrochemical environment. The redox center interacts with the solvent, and the average over the solvent configurations is performed numerically. Explicit calculations have been performed for a chain of three atoms. When the redox center interacts strongly with neighboring electronic levels, the current-potential curves show interesting features like rectification, current plateaus and negative differential resistance. Electronic spectroscopy of intermediate states can be performed at constant small bias by varying the electrochemical potential of the wire.

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Section: Resultssupporting

confidence: 79%

Electron tunneling between two electrodes mediated by a molecular wire containing a redox center

2010

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“…32 Closer examination of Tao's data shows that the current maximum for this system is also close to the equilibrium potential. 23,39,40 As a whole, the multitude of new data therefore accord broadly with the expectations of the theory. However, the application of the theory to new experimental data also shows the need to include other features in a more detailed analysis.…”

Section: Introductionsupporting

confidence: 67%

“…This current is then averaged over the distribution of the coordinates q k in the double-well potential formed by the adiabatic free energy surface U ad ͑q k ͒ 39,40,46,[48][49][50] U ad ͕͑q k ͖͒ = E͕͑q k ͖͒ + 1 2…”

Section: Appendix B: Adiabatic Transitionsmentioning

confidence: 99%

Electric double layer effect on observable characteristics of the tunnel current through a bridged electrochemical contact

Кузнецов

Medvedev

Ulstrup

2007

The Journal of Chemical Physics

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Scanning tunneling microscopy and electrical conductivity of redox molecules in conducting media (aqueous or other media) acquire increasing importance both as novel single-molecule science and with a view on molecular scale functional elements. Such configurations require full and independent electrochemical potential control of both electrodes involved. We provide here a general formalism for the electric current through a redox group in an electrochemical tunnel contact. The formalism applies broadly in the limits of both weak and strong coupling of the redox group with the enclosing metal electrodes. Simple approximate expressions better suited for experimental data analysis are also derived. Particular attention is given to the effects of the Debye screening of the electric potential in the narrow tunneling gap based on the limit of the linearized Poisson-Boltzmann equation. The current/overpotential relation shows a maximum at a position which depends on the ionic strength. It is shown, in particular, that the dependence of the maximum position on the bias voltage may be nonmonotonous. Approximate expressions for the limiting value of the slope of the current/overpotential dependence and the width of the maximum on the bias voltage are also given and found to depend strongly on both the Debye screening and the position of the redox group in the tunnel gap, with diagnostic value in experimental data analysis.

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“…In addition to disclosing a range of novel electronic tunneling features specific to singlemolecule two-electron, rather than single-electron tunneling, the system addressed is representative of electronic conductivity of redox molecules with three, instead of two electrochemically accessible oxidation states such as comprehensively reported. 1,[3][4][5][6][7][8][9][10][11][12][13][14][16][17][18][19][20] The models addressed can be extended to multilevel transitions such as in the conductivity of molecular scale metallic nanoparticles and other molecular scale "quantum dots" with several closely spaced Coulomb-based single-electron levels. 24,26,53,54 We have shown that even systems with a single redox level can display two clear peaks in the current/overpotential ͑gate voltage͒ dependence in the limit of strong electronphonon interaction.…”

Section: Discussionmentioning

confidence: 99%

“…4 and developed systematically in Refs. [5][6][7][8][9][10][11][12][13]. Experimental studies of electron tunneling through redox molecules in electrochemical environment were initiated by Tao 14 and comprehensively extended in Refs.…”

Section: Introductionmentioning

confidence: 99%

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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Mediated electron exchange between an electrode and the tip of a scanning tunneling microscope – a stochastic approach

Cited by 36 publications

References 9 publications

Electron tunneling between two electrodes mediated by a molecular wire containing a redox center

Electron tunneling between two electrodes mediated by a molecular wire containing a redox center

Electric double layer effect on observable characteristics of the tunnel current through a bridged electrochemical contact

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

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