Raman spectroscopy of carbon nanotubes under axial strain and surface-enhanced Raman spectroscopy of individual carbon nanotubes

In this thesis, I present resonant Raman spectroscopy of individual carbon nanotube bundles under axial strains up to 17%. The main effect of this strain is to cause nanotube debundling. The G band Raman spectra of metallic and semiconducting nanotubes are found to respond differently to strain and debundling, giving insight into the nature of the broad metallic G- band lineshape. For metallic nanotubes, the G- band upshifts and becomes narrower with strain, making it appear more semiconductor-like. Surprisingly, 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.