NMR chemical shift of single-wall carbon nanotubes

We report calculation of the NMR chemical shift anisotropy (CSA) tensor →μ of single-wall carbon nanotubes, within the London approximation (ring currents contribution). Our results indicate that the isotropic line as measured by high resoultion experiments is splited about 11ppm between metallic and semiconductor nanotubes. We carefully check that this result remains vaild and observable when the bundle packing is taken into account. The resulting broadening is aroune 20ppm, but reduces onto a sharp lorentzian (<1ppm) when averaging by high resoultion NMR measurements.