Kinetics of H2 desorption from crystalline C60 -: art. no. 045415

The nonequilibrium diffusion of H-2 within crystalline C-60 is examined by monitoring the outgassing of H-2 from C-60 powders. Results show that the desorption-lifetime decreases dramatically with increasing H-2 concentration. Kinetic Monte Carlo simulations indicate that diffusion occurs by H-2 molecules hopping between interstitial octahedral sites via an energetically unstable intermediary tetrahedral site. This diffusion is greatly enhanced by the presence of dimers in which two H-2 molecules briefly occupy the same octahedral site. The abundance of dimers increases with H-2 concentration and leads to simulated desorption curves that are in good agreement with the experimental outgassing data.