[sup 13]C-NMR in carbon nanotubes

Abstract

${}^{\mathrm{13}}\mathrm{C-NMR}$ studies of multi-wall carbon nanotube (MWNT), which was purified by oxidation technique, are reported. Temperature dependence of ${}^{\mathrm{13}}\mathrm{C}$ -spin lattice relaxation time. $T_1,$ clearly shows a metallic behavior, $T_1\mathrm{T=}\mathrm{const}$ law, at 9.4T between 4.2K and 77K. This suggests that there are metallic tubes in the sample at 9.4T. The field dependence of $T_{1}T$ is also discussed.