Diffusion of H2 adsorbed on single-walled carbon nanotubes

We report quasielastic neutron scattering measurements performed on H 2 adsorbed on single-walled carbon nanotubes. These measurements indicate that no quasielastic component to the scattering is present below 30 K. A quasielastic component is present at 30 K, indicating the onset of mobility of the adsorbed H 2 . This component to the scattering is well described by a liquidlike diffusion model, with a diffusion coefficient an order of magnitude greater than that of bulk liquid H 2 . The observed diffusion is consistent with two-dimensional diffusion on Grafoil and indicates that the adsorbed H 2 is leaving the groove sites of the nanotube bundles before diffusing on the outer surface of the bundles.