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

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

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.

Item Type: Article
Erschienen: 1993
Creators: Kimmig, M. and Steiner, R. and Strobl, G. and Stühn, B.
Title: Molecular dynamics in perfluoro‐n‐eicosane. IV. Oscillatory and diffusive rotational motion
Language: English
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.

Journal or Publication Title: Journal of Chemical Physics
Volume: 99
Number: 10
Divisions: 05 Department of Physics
05 Department of Physics > Institute for condensed matter physics
Date Deposited: 26 Feb 2010 13:53
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