Temperature Dependence of Tunable Raman and Fluorescence Spectroscopy of Individual Suspended Carbon Nanotubes

The temperature dependence of tunable Raman spectra are measured on single-wall carbon nanotubes grown by chemical vapor deposition (CVD) over trenches etched in quartz substrates. The suspended portion of the nanotubes exhibit enormous enhancement of the Raman and fluorescence signals relative to the unsuspended portion. Raman and fluorescence spectra are taken on the same individual nanotubes using a tunable Ti:Sapphire laser over the range 750nm-830nm. Both the Raman mode frequencies and the subband transition energies (E$_{ii}$) are observed to shift with temperature. By preparing nanotubes suspended in free space over a trench we eliminate the effects of interaction with the substrate or surfactant molecules, which, as will be shown, can be quite significant. The temperature dependence of the linewidths and resonance windows are also discussed.