Browsing by Author "Strassle, T"

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    Oxygen level dependent lattice dynamics of Na0.73CoO2-δ.
    (American Chemical Society, 2010-11-22) Tsai, PH; Donelson, R; Tan, TT; Avdeev, M; Yu, DH; Strassle, T; Li, S
    The optical and acoustic phonon branches of Na0.73CoO2-δ have been determined using Raman scattering and inelastic neutron scatterings, and their correlation with phononic thermal conductivity kph in terms of oxygen-vacancy concentration δ was investigated. The experimentally observed phonon stiffening of the Raman-active E1g mode suggests that oxygen vacancies may help stabilize texturing of Na ions that gives rise to higher kph with increasing δ. The generalized phonon density of states characterized using inelastic neutron scattering exhibits subtle stiffening of acoustic and optical phonons with δ, which appears to be responsible for the variations in kph(T) profile in the temperature range 323−923 K. © 2010, American Chemical Society
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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.