Spatially resolved Raman spectra of individual pristine suspended carbon nanotubes are observed under electrical heating. The Raman G þ and G À bands show unequal temperature profiles. The preferential heating is more pronounced in short nanotubes (2 m) than in long nanotubes (5 m). These results are understood in terms of the decay and thermalization of nonequilibrium phonons, revealing the mechanism of thermal transport in these devices. The measurements also enable a direct estimate of thermal contact resistances and the spatial variation of thermal conductivity.

Raman spectra and electrical conductance of individual, pristine, suspended, metallic single-walled carbon nanotubes are measured under applied gate potentials. The Gband is observed to downshift with small applied gate voltages, with the minima occurring at E F ) ( 1 / 2 E phonon , contrary to adiabatic predictions. A subsequent upshift in the Raman frequency at higher gate voltages results in a "W"-shaped Raman shift profile that agrees well with a nonadiabatic phonon renormalization model. This behavior constitutes the first experimental confirmation of the theoretically predicted breakdown of the Born-Oppenheimer approximation in individual single-walled carbon nanotubes.

We have mosaicked Two Micron All Sky Survey (2MASS) images to derive surface brightness profiles in J, H, and K s for 104 Galactic globular clusters. We fit these with King profiles and show that the core radii are identical to within the errors for each of these IR colors and are identical to the core radii at V in essentially all cases. We derive integrated-light colors V À J , V À H, V À K s , J À H, and J À K s for these globular clusters. Each color shows a reasonably tight relation between the dereddened colors and metallicity. Fits to these are given for each color. The IR À IR colors have very small errors, due largely to the all-sky photometric calibration of the 2MASS survey, while the V À IR colors have substantially larger uncertainties. We find fairly good agreement with measurements of integrated-light colors for a smaller sample of Galactic globular clusters by M. Aaronson, M. Malkan, and D. Kleinmann from 1977. Our results provide a calibration for the integrated light of distant single-burst old stellar populations from very low to solar metallicities. A comparison of our dereddened measured colors with predictions from several models of the integrated light of single-burst old populations shows good agreement in the lowmetallicity domain for V À K s colors but also shows an offset at a fixed [ Fe/H] of $0.1 mag in J À K s , which we ascribe to photometric system transformation issues. Some of the models fail to reproduce the behavior of the integrated-light colors of the Galactic globular clusters near solar metallicity.

Large modulations of up to 2 orders of magnitude are observed in the Raman intensity of pristine, suspended, quasimetallic, single-walled carbon nanotubes in response to applied gate potentials. No change in the resonance condition is observed, and all Raman bands exhibit the same changes in intensity, regardless of phonon energy or laser excitation energy. The effect is not observed in semiconducting nanotubes. The electronic energy gaps correlate with the drop in the Raman intensity, and the recently observed Mott insulating behavior is suggested as a possible explanation for this effect.