Browsing by Author "Grimm, H"

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    Quasi-elastic neutron spectroscopy and rotational potentials of methyl halides
    (Elsevier B. V., 2006-11-15) Kirstein, O; Prager, M; Grimm, H; Buchsteiner, A; Wischnewski, A
    The methyl halides belong to the simplest organic molecules that contain CH3 groups. The lattice dynamics of these molecules were modeled recently based on the exact crystallographic structure and transferable pair potential parameters. Experiments were done using the NEAT spectrometer at BENSC, HMI, Germany and the BSJ spectrometer at FZJ, Germany to obtain values for the individual activation energy. The experimental values for the activation energies were used to refine the Fourier parameters of the individual rotational potential. Experimentally determined activation energies for all molecules, but the methyl fluoride, agree with single particle model predictions. Crown Copyright © 2006 Published by Elsevier B.V.
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    Quasielastic neutron scattering experiments including activation energies and mathematical modeling of methyl halide dynamics
    (American Institute of Physics, 2007-09-07) Kirstein, O; Prager, M; Grimm, H; Buchsteiner, A; Wischnewski, A
    Quasielastic neutron scattering experiments were carried out using the multichopper time-of-flight spectrometer V3 at the Hahn-Meitner Institut, Germany and the backscattering spectrometer at Forschungszentrum Julich, Germany. Activation energies for CH3X, X=F, Cl, Br, and I, were obtained. In combination with results from previous inelastic neutron scattering experiments the data were taken to describe the dynamics of the halides in terms of two different models, the single particle model and the coupling model. Coupled motions of methyl groups seem to explain the dynamics of the methyl fluoride and chloride; however, the coupling vanishes with the increase of the mass of the halide atom in CH3Br and CH3I. © 2007, American Institute of Physics
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    Quasielastic neutron spectroscopy and rotational potentials of methyl halides
    (The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2005-11-27) Kirstein, O; Prager, M; Grimm, H; Buchsteiner, A; Wischnewski, A
    The methyl halides belong to the simplest organic molecules that contain CH3 groups. The lattice dynamics of these molecules were modeled recently based on the exact crystallographic structure and transferable pair potential parameters. Experiments were done using the NEAT spectrometer at BENSC, HMI, Germany and the BSJ spectrometer at FZJ, Germany to obtain values for the individual activation energy. The experimental values for the activation energies were used to refine the Fourier parameters of the individual rotational potential. Experimentally determined activation energies for all molecules, but the methyl fluoride, agree with single particle model predictions. © The Authors