DYNAMICS AND FRICTION IN DOUBLE WALLED CARBON NANOTUBES

Product Description
Nanotubes have exceptional physical properties, they are as tough as diamond and excellent heat and electricity conductors. On the other hand their cylindrical shape suggests the possibility of using them as mechanical parts at the nanoscale. Recent experiments showed that oscillators or rotational axes could be manufactured and controlled. Moreover the motion was observed to be wearless and with extremely low friction. This book shows analytical and numerical results on the dynamics and friction in those systems. The results show that the empirical law stating that friction is proportional to the area of contact is very well verified. Moreover, friction increases with temperature. These dependencies can be easily interpreted. Indeed, if the temperature is large enough so that electronic effects can be negligible, then dissipation is only due to the phonons. Consequently, if the temperature increases, the coupling between the phonons and the rotational or oscillatory motions increases, as well as friction. In the same manner, when the area of contact increases, the number of available phonons to transport energy increases, resulting in a higher friction force.

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Raman Spectroscopy of Carbon Nanotubes under Axial Strain: Raman Spectroscopy of Carbon Nanotubes under Axial Strain and Surface-Enhanced Raman Spectroscopy of Individual Carbon Nanotubes

Product Description
Resonant Raman spectroscopy of individual carbon nanotube bundles under axial strains up to 17% are presented. This strain causes nanotube debundling which gives insight into the nature of the broad metallic G- band. For metallic nanotubes, the G- band upshifts and narrows with strain, making it appear more semiconductor-like. This metal to semiconductor transition is irreversible with strain, indicating that nanotube-nanotube coupling plays a significant role in the observed G- band of metallic nanotubes. The vibrational and electronic properties of these nanotubes under strain are modeled using tight-binding calculations. A systematic study of surface enhanced Raman spectroscopy (SERS) of carbon nanotubes. Raman spectra of individual carbon nanotubes are measured before and after depositing silver nanoparticles. Regions exhibiting SERS enhancement were located relative to a grid, allowing subsequent scanning electron microscopy to be performed. SERS enhancement factors up to 134,000, a consistent upshift in the G band Raman frequency and nanoparticle heating in excess of 600°C are revealed.

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