Open or Close Ended Growth for Multiwalled Nanotubes

Assuming first that the tube remains closed during growth, the longitudinal growth of the tube occurs by the continuous incorporation of small carbon clusters (C2 dimers). This C2 absorption process is assisted by the presence of pentagonal defects at the tube end, allowing bond-switching in order to reconstruct the cap topology 13,14 . Such a mechanism implies the use of the Stone-Wales mechanism to bring the pentagons of the tip at their canonical positions at each C2 absorption. This model...

Controlled Nanotube Growth by Chemical Vapor Deposition

Recent interest in CVD nanotube growth is also due to the idea that aligned and ordered nanotube structures can be grown on surfaces with control that is not possible with arc-discharge or laser ablation techniques 23,32 . 2.1 Aligned Multi-Walled Nanotube Structures Methods that have been developed to obtain aligned multi-walled nanotubes include CVD growth of nanotubes in the pores of mesoporous silica, an approach developed by Xie's group at the Chinese Academy of Science 33,34 . The...

Applications in Chemical Force Microscopy and Force Spectroscopy

In Chemical Force Microscopy CFM , the AFM tip is modified with specific chemical functional groups 90 . This enables the tip to generate contrast dependent on the chemical properties of the sample from the friction signal in contact mode or the phase lag signal in tapping mode simultaneously with topography 91 . Functionalized tips have also been employed in force spec-troscopy. In this mode of operation the tip is brought into contact with a surface, then retracted. The forces applied to the...

Resonance Raman Scattering of MWNTs

Multi-walled carbon nanotubes MWNTs prepared by the carbon arc method are thought to be composed of a coaxial arrangement of concentric nanotubes. For example, 13C-NMR 64 and magnetoresistance measurements 65,66 show Aharonov-Bohm effects that are associated with the concentric tube structures. On the other hand, the thermal expansion measurements 67 and the doping effects 68 suggest that some kinds of MWNTs have scroll structures. If the RBMs, which are characteristic of SWNTs 35 , are...

References

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