title: Neutron scattering and molecular dynamics evidence for levitation effect in nanopores.
abstract: Neutron scattering measurements and molecular dynamics simulations have been carried out on the three isomers of pentane (neopentane (neo), isopentane (iso), and n-pentane (n-)) adsorbed in zeolite NaY. The results show that the self-diffusivity of these isomers follow the order Ds(neo)>Ds(iso)>Ds(n-), suggesting that the larger the cross section perpendicular to the molecular axis of the isomer, the higher the self-diffusivity. This counterintuitive result provides the first direct experimental evidence in support of the mutual cancellation of forces on the diffusant leading to a diffusivity maximum and is often referred to as the levitation effect. We also provide a direct confirmation of the experimental observations by Kemball (Adv. Catal. 1950, 2, 233) by calculating the entropy.
authors.affiliation: Institut de recherches sur la catalyse et l'environnement de Lyon, Universite Lyon 1, CNRS, UMR 5256, IRCELYON, 2 Avenue Albert Einstein, F-69626 Villeurbanne, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Jobic
authors.forename: Bhaskar J
authors.initials: BJ
authors.lastname: Borah
authors.forename: Subramanian
authors.initials: S
authors.lastname: Yashonath