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

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

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. ; Steiner, R. ; Strobl, G. ; Stühn, B.
Type of entry: Bibliographie
Title: Molecular dynamics in perfluoro‐n‐eicosane. IV. Oscillatory and diffusive rotational motion
Language: English
Date: November 1993
Journal or Publication Title: Journal of Chemical Physics
Volume of the journal: 99
Issue Number: 10
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.

Divisions: 05 Department of Physics
05 Department of Physics > Institute for condensed matter physics (2021 merged in Institute for Condensed Matter Physics)
Date Deposited: 26 Feb 2010 13:53
Last Modified: 05 Mar 2013 09:32
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