Quasi-elastic neutron scattering of benzene in Na-mordenite

Abstract

The rotational and translational dynamics of benzene adsorbed in Na-mordenite have been studied by incoherent quasi-elastic neutron scattering. The measurements were performed at two benzene coverages at 300, 400 and 450 K. The observed quasi-elastic broadenings are described by a uniaxial rotational model about the six-fold axis of benzene. The mean time between successive jumps, at 300 K, is τ=1.45 × 10 −12 s at low coverage and 2.05×10 −12 s at high coverage. The correlation times follow an Arrhenius law with E A =4.51 kJ mol −1, at both coverages. The translational diffusion coefficient has been measured at 300 K and was found to be 0.67 × 10 −6 cm 2s −1.