Neutron scattering and cation rotational motion in tetramethylammonium manganese chloride
- 1 January 1973
- journal article
- Published by EDP Sciences in Journal de Physique
- Vol. 34 (5-6), 473-481
- https://doi.org/10.1051/jphys:01973003405-6047300
Abstract
The scattering of neutrons by a polycrystalline sample of tetramethylammonium manganese chloride has been measured for 0-500 cm-1 energy transfers, both below and above the phase transition at 128 K. In the 0-50 cm-1 region, which reflects the rotational motion of the polyatomic cations, the scattered spectrum exhibits an inelastic peak at low temperature, but only a shoulder extending from the quasi-elastic peak in the high temperature phase. These spectra are semi-quantitatively interpreted by a model which assumes that the tetramethylammonium ions experience a three-well crystalline field and random torque-impulses for simulating the contact with the thermal bath. The fit of this model to the experimental data shows that the potential barrier is sufficiently high in the low temperature phase for the cations to perform a librational motion of relatively long duration in a given well. By contrast, in the high temperature phase, the motion is rather that of a slightly hindered rotatorKeywords
This publication has 8 references indexed in Scilit:
- High-Resolution Inelastic Neutron Scattering from Some Aromatic Molecular Polycrystals for Study of Crystal Excitations and Anharmonic EffectsThe Journal of Chemical Physics, 1972
- Single-crystal Raman and far-infrared study of tetramethylammonium trichloromanganate(II)Inorganic Chemistry, 1971
- Statistical dynamics of a rotator in a potential of cubic symmetryMolecular Physics, 1971
- The pre-exponential factor in activated reorientational processesChemical Physics Letters, 1969
- Statistical dynamics of a classical hindered rotatorDiscussions of the Faraday Society, 1969
- Rotational Correlation Functions in Neutron Scattering by Molecular GasesPhysical Review B, 1968
- Crystal structure of tetramethylammonium manganese(II) chlorideActa Crystallographica, 1967
- THEORY OF COLD NEUTRON SCATTERING BY HOMONUCLEAR DIATOMIC LIQUIDS: II. HINDERED ROTATIONCanadian Journal of Physics, 1966