Single-walled nanotubes electronic structure

Experimental measurements to test these remarkable theoretical predictions of the electronic structure of carbon nanotubes are difficult to carry out because of the strong dependence of the predicted properties on tubule diameter and chirality. Ideally, electronic or optical measurements should be made on individual single-wall nanotubes that have been characterized with regard to diameter and chiral angle. Further ex-... 

This suggests that the geometric differences (e.g. bends, helicity, diameter, etc.) and graphitisation of the structures play important roles in the electronic behaviour. In addition, bundles of single-walled nanotubes have been shown to behave as metals with resistivities in the 0.34 x 10 to 1.0 x 10" ohm cm range... 

This paper focuses mainly on the mechanical properties of carbon nanotubes and di.scusses their elastic properties and strain-induced transformations. Only. single-walled nanotubes are di.scussed, since they can be grown with many fewer defects and are thus much stronger. It is shown that under suitable conditions some nanotubes can deform plasiically, while others must break in a brittle fashion. A map of brittle vs. ductile behavior of carbon nanotubes with indices up to (100,100) is presented. The electrical properties of nanotubes are also affected by strain. We will focus here on quantum (ballistic) conductance, which is very sensitive to the atomic and electronic structure. It turns out that some nanotubes can tolerate fairly large deformations without much change to their ballistic conductance, while others are quite sensitive. Both properties can be used in applications, provided that nanotubes of the appropriate symmetry can be reliably prepared or selected. 

Raman spectroscopy of single-walled nanotubes is known to be resonant. This means that the wavelength of the laser used influences the intensity and the shape of the characteristic modes. With a wavelength of 632.817 nm the intensity of the RBM is higher (Figure 3.46) and the shape of the TM differs from the one obtained at 514.5 nm. Resonant Raman spectroscopy of single-walled carbon nanotubes can be explained by the electronic structure of carbon... 

Chen, W., Yu, G.-T., Gu, F.L., Aoki, Y Investigation on the electronic structures andnonUnear optical properties of pristine boron nitride and boron nitride-carbon heterostructured single-wall nanotubes by the elongation method. J. Rhys. Chem. C 113, 8447-8454 (2009)... 

Carbon nanotubes have been studied extensively since their discovery [1] in 1991, because of the extraordinary physical properties they exhibit in electronic, mechanical, and thermal processes. A single-walled nanotube may be considered as a specific, one-dimensional giant molecule composed purely of carbon, whereas properties of multiwalled nanotubes are closest to those of graphite s in-plane properties, having sp hybridization of carbon bonds. To prepare closed-shell structures, one needs to insert topological defects into the hexagonal stmcture of graphene sheets. The extraordinary physical and chemical properties [2] and possible applications derived from these properties are attributed to the one-dimensionality and helicity of the nanotube structure. 

Structurally, carbon nanotubes of small diameter are examples of a onedimensional periodic structure along the nanotube axis. In single wall carbon nanotubes, confinement of the stnreture in the radial direction is provided by the monolayer thickness of the nanotube in the radial direction. Circumferentially, the periodic boundary condition applies to the enlarged unit cell that is formed in real space. The application of this periodic boundary condition to the graphene electronic states leads to the prediction of a remarkable electronic structure for carbon nanotubes of small diameter. We first present... 

Electronic Structures of Single-Walled Carbon Nanotubes... 

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