NMR of hydrogen adsorbed on carbon nanotubes.

Hydrogen gas is introduced to multi-walled carbon nanotubes and 1H nuclear magnetic resonances are measured as the functions of hydrogen gas pressure and temperature. The resonance frequency is shifted in inverse proportion to temperature due to the super-paramagnetic Fe catalysts that remained in the nanotubes. By the differences in relaxation times, the signal from hydrogen adsorbed on carbon nanotubes is differentiated from that of gas phase hydrogen. [Copyright &y& Elsevier]