Browsing by Author "Kelly, Kevin Francis"

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    Functionalization of scanning tunneling microscope probes with buckminsterfullerenes
    (1996) Kelly, Kevin Francis; Halas, Naomi J.
    This dissertation analyzes the feasibility and advantages of molecular functionalization of scanning tunneling microscope (STM) probes with buckminsterfullerenes. The C$\sb{60}$ molecules are adsorbed onto the tunneling region of a STM tip by rastering the tip in a thin film of C$\sb{60}$ vacuum deposited on graphite. The individual tip-adsorbed molecules are subsequently imaged in situ by scanning the fullerene-adsorbed tip over a defect covered graphite surface. These nanometer-size defects serve as a surface tip array which images the molecules adsorbed to the tip when the surface is scanned. It is then demonstrated that the fullerene-adsorbed STM tips can be used to observe electron scattering from point defects and steps on graphite. This cannot be observed using bare metal tips. Molecular functionalization adds a new dimension to scanning tunneling microscopy by allowing greater control of the electronic interactions between the tip and sample.
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    Investigating the electronic properties of carbon nanostructures with scanning tunneling microscopy
    (1999) Kelly, Kevin Francis; Halas, Naomi J.
    Utilizing the scanning tunneling microscope, the electronic and structural properties of a variety of carbon based nanostructures, are explored. Among these, threefold electron scattering on graphite generated by vacancies and adsorbates is imaged using C60-functionalized STM tips. By comparing a simple theoretical model to the experimental results, it is possible to identify the exact location of the defect in the graphite lattice. It is also possible to qualitatively identify the bonding strength of various adsorbates. In addition to graphite, monolayers of disulfide derivatized fullerenes are probed with the STM. The self-assembling and electronic properties of these molecules are investigated. Lastly, comparisons are drawn from these experiments to similar investigations of functionalized carbon nanotubes.