Raman Spectroscopy of Carbon Nanotube Sensors
Raman spectroscopy is used for the first time to measure individual carbon nanotubes (SWNTs), strained by manipulation with an atomic force microscope (AFM) tip. Metallic nanotubes are found to shift on and off resonance with strain, implying a strain-induced shifting of the electronic band energies of the nanotube. We find that individual nanotubes are far more sensitive to strain than their bulk counterpart (graphite). We can observe changes in the Raman spectra for strains as small as 0.1%, which corresponds to a displacement of ~10 nm. The extreme sensitivity of nanotubes to strain and other perturbations make them suitable for many potential applications.