Raman Spectroscopy of Carbon Nanotubes under Axial Strain

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.

Autorentext

Rajay Kumar graduated from MIT with a B.S. and M.Eng. inElectrical Engineering in 2003, working under Professor MarcBaldo. In 2008, he earned his Ph.D. from USC, working underProfessor Stephen Cronin. His research includes the Ramanspectroscopy of carbon nanotubes under axial strain andinvestigating surface-enhanced Raman spectroscopy (SERS).

Klappentext

Resonant Raman spectroscopy of individual carbonnanotube bundles under axial strains up to 17% arepresented. This strain causes nanotube debundlingwhich gives insight into the nature of the broadmetallic G- band. For metallic nanotubes, the G- bandupshifts and narrows with strain, making it appearmore semiconductor-like. This metal to semiconductortransition is irreversible with strain, indicatingthat nanotube-nanotube coupling plays a significantrole in the observed G- band of metallic nanotubes.The vibrational andelectronic properties of these nanotubes under strainare modeled using tight-bindingcalculations.A systematic study of surface enhanced Ramanspectroscopy (SERS) of carbon nanotubes. Ramanspectra of individual carbon nanotubes are measuredbefore and after depositing silver nanoparticles.Regions exhibiting SERS enhancement were locatedrelative to a grid, allowing subsequent scanningelectron microscopy to be performed. SERS enhancementfactors up to 134,000, a consistent upshift in the Gband Raman frequency and nanoparticle heating inexcess of 600°C are revealed.