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Molecular dynamics in perfluoro‐n‐eicosane. IV. Oscillatory and diffusive rotational motion

Kimmig, M. ; Steiner, R. ; Strobl, G. ; Stühn, B. :
Molecular dynamics in perfluoro‐n‐eicosane. IV. Oscillatory and diffusive rotational motion.
In: Journal of Chemical Physics, 99 (10) S. 8105-8114.
[Artikel] , (1993)

Kurzbeschreibung (Abstract)

Rotations of the molecules about their long axis constitute an important part in the complex pattern of internal motions in the rhombohedral phase of perfluoro-n-eicosane (C20F42). Dynamical studies were performed by quasielastic and inelastic neutron scattering. Spectra were determined in a range of strong diffuse scattering. They show a superposition of librations (deltaE congruent-to 1-2 meV) and rotational diffusion (deltaE congruent-to 10-100 mueV). Reorientation rates exhibit a slowing down on approaching the transition to the low temperature phase (T(c) = 200 K). As indicated by this slowing down, by the nonexponential relaxation function, and also an intensity enhancement at the Bragg-positions, rotations occur correlated between neighboring molecules. The state of motion can be simulated by molecular dynamics calculations performed for a two-dimensional lattice of coupled rotators.

Typ des Eintrags: Artikel
Erschienen: 1993
Autor(en): Kimmig, M. ; Steiner, R. ; Strobl, G. ; Stühn, B.
Titel: Molecular dynamics in perfluoro‐n‐eicosane. IV. Oscillatory and diffusive rotational motion
Sprache: Englisch
Kurzbeschreibung (Abstract):

Rotations of the molecules about their long axis constitute an important part in the complex pattern of internal motions in the rhombohedral phase of perfluoro-n-eicosane (C20F42). Dynamical studies were performed by quasielastic and inelastic neutron scattering. Spectra were determined in a range of strong diffuse scattering. They show a superposition of librations (deltaE congruent-to 1-2 meV) and rotational diffusion (deltaE congruent-to 10-100 mueV). Reorientation rates exhibit a slowing down on approaching the transition to the low temperature phase (T(c) = 200 K). As indicated by this slowing down, by the nonexponential relaxation function, and also an intensity enhancement at the Bragg-positions, rotations occur correlated between neighboring molecules. The state of motion can be simulated by molecular dynamics calculations performed for a two-dimensional lattice of coupled rotators.

Titel der Zeitschrift, Zeitung oder Schriftenreihe: Journal of Chemical Physics
Band: 99
(Heft-)Nummer: 10
Fachbereich(e)/-gebiet(e): 05 Fachbereich Physik
05 Fachbereich Physik > Institut für Festkörperphysik
Hinterlegungsdatum: 26 Feb 2010 13:53
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