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Single-Molecule Tribology: Force Microscopy Manipulation of a Porphyrin Derivative on a Copper Surface
02.12.2015 10:40

Article

  • Single-Molecule Tribology: Force Microscopy Manipulation of a Porphyrin Derivative on a Copper Surface

Authors

  • Rémy Pawlak - Department of Physics, University of Basel, Switzerland
  • Wengen Ouyang - Center for Nano and Micro Mechanics, Tsinghua University Beijing, China
  • Alexander E. Filippov - Donetsk Institute for Physics and Engineering, National Academy of Sciences of Ukraine, Donetsk
  • Lena Kalikhman-Razvozov - Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Israel
  • Shigeki Kawai - Department of Physics, University of Basel, Switzerland
  • Thilo Glatzel - Department of Physics, University of Basel, Switzerland
  • Enrico Gnecco - OSIM, FSU Jena, Germany
  • Alexis Baratoff - Department of Physics, University of Basel, Switzerland
  • Quanshui Zheng - Center for Nano and Micro Mechanics, Tsinghua University Beijing, China
  • Oded Hod - Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Israel
  • Michael Urbakh - Department of Physical Chemistry, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, and The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Israel
  • Ernst Meyer - Department of Physics, University of Basel, Switzerland

Journal

Abstract

  • The low-temperature mechanical response of a single porphyrin molecule attached to the apex of an atomic force microscope (AFM) tip during vertical and lateral manipulations is studied. We find that approach-retraction cycles as well as surface scanning with the terminated tip result in atomic-scale friction patterns induced by the internal reorientations of the molecule. With a joint experimental and computational effort, we identify the dicyanophenyl side groups of the molecule interacting with the surface as the dominant factor determining the observed frictional behavior. To this end, we developed a generalized Prandtl-Tomlinson model parametrized using density functional theory calculations that includes the internal degrees of freedom of the side group with respect to the core and its interactions with the underlying surface. We demonstrate that the friction pattern results from the variations of the bond length and bond angles between the dicyanophenyl side group and the porphyrin backbone as well as those of the CN group facing the surface during the lateral and vertical motion of the AFM tip.

Link to Publication via DOI.org:

Mechanical response during lateral displacement

Mechanical response during lateral displacement

Dependence of the mechanical response during lateral displacement on the tip–surface distance

Dependence of the mechanical response during lateral dis­place­ment on the tip–surface distance

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