Log Number: 84

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Density Waves and STM Imaging of Carbon Nanotubes
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University of Pennsylvania

Scanning tunneling images of carbon nanotubes frequently show electron distributions which break the local sixfold symmetry of the graphene sheet. We will discuss a theory of these images which relates the anisotropies to off diagonal correlations in the single particle density matrix induced by elastic scattering from tube defects. The theory reveals that there are three general effects which one can associate with defect scattering; any defect can be characterized by a matrix of reflection coefficients which then define its singature in the tunneling image. We will discuss distributions with broken translational symmetry, "primitive" broken symmetry images with broken rotational symmetry but no broken translational symmetry, and a novel switching of the image symmetry with sign of tunneling bias predicted for semiconducting tubes. Experimental data illustrating each of these effects will be presented.

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Last modification:
1999.07.15 (Thursday) 11:39:41 EDT