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Reorganization energy upon charging a single molecule on an insulator measured by atomic force microscopy

Nature Nanotechnologyvolume 13pages376380 (2018) | Download Citation


Intermolecular single-electron transfer on electrically insulating films is a key process in molecular electronics1,2,3,4 and an important example of a redox reaction5,6. Electron-transfer rates in molecular systems depend on a few fundamental parameters, such as interadsorbate distance, temperature and, in particular, the Marcus reorganization energy7. This crucial parameter is the energy gain that results from the distortion of the equilibrium nuclear geometry in the molecule and its environment on charging8,9. The substrate, especially ionic films10, can have an important influence on the reorganization energy11,12. Reorganization energies are measured in electrochemistry13 as well as with optical14,15 and photoemission spectroscopies16,17, but not at the single-molecule limit and nor on insulating surfaces. Atomic force microscopy (AFM), with single-charge sensitivity18,19,20,21,22, atomic-scale spatial resolution20 and operable on insulating films, overcomes these challenges. Here, we investigate redox reactions of single naphthalocyanine (NPc) molecules on multilayered NaCl films. Employing the atomic force microscope as an ultralow current meter allows us to measure the differential conductance related to transitions between two charge states in both directions. Thereby, the reorganization energy of NPc on NaCl is determined as (0.8 ± 0.2) eV, and density functional theory (DFT) calculations provide the atomistic picture of the nuclear relaxations on charging. Our approach presents a route to perform tunnelling spectroscopy of single adsorbates on insulating substrates and provides insight into single-electron intermolecular transport.

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  • 19 April 2018

    In the version of this Letter originally published, a technical error led to the following spurious text being included "Whis it it that this E_reorg term is differently highlighted than the E_reorg term in the first line of this paragraph? They are the same term."; this text has now been removed from all versions of the Letter.


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We thank R. Allenspach for comments. Financial support by the European Research Council (advanced grant ‘CEMAS’, agreement no. 291194, and consolidator grant ‘AMSEL’, agreement no. 682144), EU projects ‘PAMS’ (contract no. 610446) and Initial Training Network ‘ACRITAS’ (contract no. 317348). The Leverhulme Trust (F/00 025/AQ) and the allocations of computer resources at Chadwick, The University of Liverpool, are gratefully acknowledged. I.S. acknowledges CCP5 funding and associated CoSeC support at STFC via EPSRC grant no. EP/M022617/1 and SLA for funding.

Author information

Author notes

    • Bruno Schuler

    Present address: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    • Ivan Scivetti

    Present address: Daresbury Laboratory, Sc. Tech., Warrington, UK


  1. IBM Research – Zurich, Rüschlikon, Switzerland

    • Shadi Fatayer
    • , Bruno Schuler
    • , Wolfram Steurer
    • , Leo Gross
    •  & Gerhard Meyer
  2. Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool, UK

    • Ivan Scivetti
    •  & Mats Persson
  3. Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany

    • Jascha Repp
  4. Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden

    • Mats Persson


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S.F, W.S., J.R., L.G. and G.M. designed the experiments. S.F., B.S., L.G. and G.M. performed the experiments. S.F. carried out the finite-element simulations. M.P. and I.S. were responsible for the DFT calculations. All the authors discussed the results and wrote the manuscript.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Shadi Fatayer.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–9, Supplementary Table 1

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