Quantum Rotation of Ammonia Molecules in Disordered Ca(NH3)6

  • F. Leclercq
  • P. Damay
  • A. J. Dianoux
  • W. Press
Part of the Springer Proceedings in Physics book series (SPPHY, volume 17)


Calcium hexaammine is a low electron density, metallic compound. In this expanded metal, the ammonia molecules show important rotational and reorientational motions down to 20 K as deduced from the study of the quasielastic neutron scattering ( LECLERCQ et al./1/ ). A complete understanding of the inelastic scattering needs a simultaneous determination of the structure in the whole temperature range. Since the calcium compound crystallizes in a high symmetry group (bcc) and since no phase transition occurs as the temperature is decreased, the ammonia molecules appear to be in a frozen-in orientationally disordered state at low temperature. For temperature lower than 10 K, the Inelastic Neutron Scattering spectrum shows a very asymmetric line shape with a maximum near the energy of uniaxial rotation of the NH3 / ND3 groups. This is interpreted by quantum rotation in a (random) distribution of low hindering potentials. It is shown that these properties are very sensitive to non-stoichiometry effects.


Inelastic Scattering Ammonia Molecule Rotational Excitation Spectrometer Resolution Reorientational Motion 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1987

Authors and Affiliations

  • F. Leclercq
    • 1
  • P. Damay
    • 1
  • A. J. Dianoux
    • 2
  • W. Press
    • 3
  1. 1.LESI, UA 253 du CNRSLille CedexFrance
  2. 2.Institut Laue-Langevin, 156XGrenoble CedexFrance
  3. 3.Institut für ExperimentalphysikUniversität KielKiel 1Fed. Rep. of Germany

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