Browsing by Author "Shadmi, Nitzan"

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    Charge transfer between carbon nanotubes on surfaces.
    (2015) Araujo, Karolline Aparecida de Souza; Barboza, Ana Paula Moreira; Fernandes, Thales Fernando Damasceno; Shadmi, Nitzan; Joselevich, Ernesto; Mazzoni, Mário Sérgio de Carvalho; Neves, Bernardo Ruegger Almeida
    The charge transfer between neighboring single-walled carbon nanotubes (SWNTs) on a silicon oxide surface was investigated as a function of both the SWNT nature (metallic or semiconducting) and the anode/cathode distance using scanning probe techniques. Two main mechanisms were observed: a direct electron tunneling described by the typical Fowler–Nordheim model, and indirect electron transfer (hopping) mediated by functional groups on the supporting surface. Both mechanisms depend on the SWNT nature and on the anode/cathode separation: direct electron tunneling dominates the charge transfer process for metallic SWNTs, especially for large distances, while both mechanisms compete with each other for semiconducting SWNTs, prevailing one over the other depending on the anode/cathode separation. These mechanisms may significantly influence the design and operation of SWNT-based electronic devices.
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    Dynamics of the formation of carbon nanotube serpentines.
    (2013) Machado, L. D.; Legoas, S. B.; Soares, Jaqueline dos Santos; Shadmi, Nitzan; Jorio, A.; Joselevich, E.; Galvão, D. S.
    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] reported the experimental realization of carbon nanotube S-like shaped nanostructures, the so-called carbon nanotube serpentines. We report here results from multimillion fully atomistic molecular dynamics simulations of their formation. We consider one-_m-long carbon nanotubes placed on stepped substrates with and without a catalyst nanoparticle on the top free end of the tube. A force is applied to the upper part of the tube during a short period of time and turned off; then the system is set free to evolve in time. Our results show that these conditions are sufficient to form robust serpentines and validates the general features of the ‘‘falling spaghetti model’’ proposed to explain their formation.