Localized Structures in Nanotubes

The above results focus on the properties of defect-free, nearly infinite SWNTs. Nanotubes can, however, exhibit a variety of structural defects. For example, the insertion of a pentagon-heptagon (5-7) pair in the hexagonal network [30,31] can produce a kink in the tubular nanotube structure. Also, more gradual bends can result from mechanical distortions and bending. In addition, structural deformations such as bends, twisting, and collapse have been observed occasionally in these seemingly infinite carbon cylinders [32,33,34]. These defects may develop during growth, processing, deposition, or following an interaction with surface features [35]. The electronic properties of localized SWNT structures, such as bends and ends [36,37,38], are essential to proposed device applications. Below selected examples of structures that have been characterized with atomically-resolved imaging and spectroscopy are described.

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