Abstract Submitted to the    NANOTUBE'04 Conference:

Results from resonant Raman and photoluminescence (PL) measurements of single wall carbon nanotubes (SWNTs) have varied significantly with the nanotube environment. In contrast, the inner tube in DWNTs is shielded by and is only weekly interacting with the outer tube, providing an appealing system for studies of intrinsic properties. The sample is dominated by DWNTs with small inner tube diameters (< 1 nm). Resonant Raman scattering is used to characterize both low density ensembles and individual double wall carbon nanotubes. The variation in frequency with diameter for radial breathing modes allows measurements of narrow line-widths, 1-2 cm-1, even for ensemble data. The range of RBM frequencies demonstrates tube diameters <0.6 nm, in accordance with statistics from TEM data. Several examples of inner and outer pairs are observed for individual DWNTs RBMs. Optical heating of the DWNTs tunes the scattering in or out of resonance, while the linewidths are only weekly dependent on the temperature. However, PL data show strikingly narrow linewidths, 1-4 meV, even for temperatures well above room temperature. Furthermore, the ration of excitation to emission energy is larger than has previously been observed for SWNTs, either suspended or dispersed in micelles.