Diffusion of acetylene embedded in Na-Y zeolite: QENS and MD simulation studies

We report here the studies of the dynamics of acetylene molecules adsorbed in Na-Y zeolite cages using Quasielastic neutron scattering (QENS) and molecular dynamics (MD) simulation techniques. MD simulation shows that the translational motion of the acetylene molecules occurs at three different time scales. While the first component corresponds to very fast motion which is not likely to be observed through the present QENS spectrometer used, the combined half width at half maxima from the other two matches reasonably well with that obtained from the experiment. Rotational motions are found to be very fast and not likely to be observed in the present QENS experiment. (c) 2006 Elsevier B.V. All rights reserved.