Quasi-elastic neutron scattering measurements, performed on H2 adsorbed on single-walled carbon nanotubes, were reported. These measurements indicated that no quasi-elastic component in the scattering was present below 30K. A quasi-elastic component was present at 30K, indicating the onset of mobility of the adsorbed H2. This component of the scattering was well-described by a liquid-like diffusion model, with a diffusion coefficient that was an order of magnitude greater than that of bulk liquid H2. The observed diffusion was consistent with two-dimensional diffusion on Grafoil and indicated that the adsorbed H2 was leaving the groove sites of the nanotube bundles before diffusing on the outer surface of the bundles.

Diffusion of H2 Adsorbed on Single-Walled Carbon Nanotubes. Narehood, D.G., Pearce, J.V., Eklund, P.C., Sokol, P.E., Lechner, R.E., Pieper, J., Copley, J.R.D., Cook, J.C.: Physical Review B, 2003, 67[20], 205409