The dynamics of acetylene molecules adsorbed in Na-Y zeolite cages was investigated. The translational motion of the acetylene molecules was shown to involve three different time-scales. So-called free-particle diffusion was observed at short times and small length-scales. At long times and large length-scales, center-of-mass motion of acetylene was governed by the zeolitic pore topology. Rotational motion of the acetylene was found to be very fast. A detailed analysis of the intermediate scattering function corresponding to rotational motion indicated large-angle jumps that could be described by an m-diffusion model.

Diffusion of Acetylene inside Na-Y Zeolite: Molecular Dynamics Simulation Studies. G.Gautam, S.Mitra, R.Mukhopadhyay, S.I.Chaplot: Physical Review E, 2006, 74[4], 041202