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playing with molecules

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  • David Forrest
    ... APPLIED PHYSICS: Twisting an Arm Gently ... Ian S. Osborne The ability to manipulate single molecules and their electronic properties offers the
    Message 1 of 1 , Feb 15, 2001
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      APPLIED PHYSICS: Twisting an Arm Gently
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      Ian S. Osborne

      The ability to manipulate single molecules and their electronic properties
      offers the opportunity to use them as active elements in nanoscale
      electronics. Moresco et al. demonstrate that a scanning tunneling
      microscope can be used to induce a conformational change in a single
      molecule; this alters the electronic properties of the tunnel junction. A
      derivatized porphyrin molecule is deposited onto a copper surface with its
      four arms (di-tert-butylphenyl groups) perpendicular to the plane of the
      porphyrin and the surface. The tip of a scanning tunneling microscope (STM)
      is brought close to just one of the arms, and a gentle nudge serves to
      twist the arm into an orientation parallel to the surface. The tunneling
      current through the arm depends on the extent of the rotation. A 90{o}
      rotation induces the maximum change (of over six orders of magnitude) in
      resistance, which can be reversed by nudging the arm back up to its
      original position. -- ISO

      Phys. Rev. Lett. 86, 672 (2001).
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