Browsing by Author "Li, JC"

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    Neutron scattering study of water confined in periodic mesoporous organosilicas
    (Elsevier, 2010-07) Levy, E; Chan, LK; Yu, DH; Koza, MM; Mastai, Y; Ford, RC; Li, JC
    A series of quasi-elastic neutron scattering measurements were performed using IN6 at the Institute Laue Langevin for a mesoporous organosilica material with phenyl functions, called phenyltriethoxysilane (PTES). The aim of the experiment was to study the diffusion dynamics of nano-scale water clusters inside the hydrophobic pores as a function of temperature and hydration. By fitting the Debye–Waller factor, the data show clearly the different behavior between water, both inside and outside the hydrophobic pores, which resembles bulk water. The mean thermal displacement u2 of the external water increases with T almost linearly up to 353 K, while the internal water quickly reaches the maximum at T323 K, indicating the confinement by an averaged pore diameter of the porous organosilica. © 2010, Elsevier Ltd.
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    Proline induced disruption of the structure and dynamics of water
    (Royal Society of Chemistry, 2013-01-01) Yu, DH; Hennig, M; Mole, RA; Li, JC; Wheeler, C; Strassle, T; Kearley, GJ
    We use quasi-elastic neutron scattering spectroscopy to study the diffusive motion of water molecules at ambient temperature as a function of the solute molar fraction of the amino acid, proline. We validate molecular dynamics simulations against experimental quasielastic neutron scattering data and then use the simulations to reveal, and understand, a strong dependence of the translational self-diffusion coefficient of water on the distance to the amino acid molecule. An analysis based on the juxtaposition of water molecules in the simulation shows that the rigidity of proline imposes itself on the local water structure, which disrupts the hydrogen-bond network of water leading to an increase in the mean lifetime of hydrogen bonds. The net effect is some distortion of the proline molecule and a slowing down of the water mobility. © 2013, Royal Society of Chemistry.
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    Quasi-elastic neutron scattering study of water confined in periodic mesoporous organosilicas
    (Physical Society of Japan, 2012-12-18) Yu, DH; Page, DE; Li, JC; Mastau, Y; Koza, MM; Kearley, GJ
    Water confined in nanoscale space behaves significantly differently from bulk water. We have applied the Quasi-Elastic Neutron Scattering technique to investigate diffusive properties of water confined in porous silicate coated with hydrophobic organic functional groups, at two different levels of hydration. The measurements were performed over a wide range of temperatures, and although we cannot exclude subdiffusion, the data are more easily understood from a distribution in the diffusive dynamics ranging from static water monolayer at the pore surface to much greater mobility towards the pore centre. There is some evidence for a local diffusive motion with an effective radius of about 3.5 Å. The overall diffusion constants are significantly less than bulk water over the same temperature ranges. © 2013, The Physical Society of Japan.