Temperature dependence of the molecular reorientation rates in the plastic solid phase of 1-fluoroadamantane: An incoherent quasielastic neutron scattering study

Using the incoherent quasielectric neutron scattering technique, we have studied the molecular reorientations of 1-fluoroadamantane C10H15F in its plastic phase. The measurements were done in a temperature range from 253 K to 413 K, using a powder specimen. It is shown that molecular motions consist of reorientational jumps between three equilibrium positions equally spaced by 120° around the molecule symmetry axis, together with a tumbling of the molecule from one [111] lattice direction to another. The resulting values of correlation times follow the two Arrhenius laws At the highest temperatures of experiment, a description on the basis of the rotational diffusion model is also examined.

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