Stochastic NH 3-rotation in [Ni(NH 3) 6](ClO 4) 2 crystals studied by the neutron incoherent scattering method

Abstract

Quasielastic neutron scattering were spectra measured for polycrystalline [Ni(NH 3) 6](ClO 4) 2. The spectra have been interpreted using models describing the stochastic NH 3-rotational motions. The two models: 120°-jumps and the uniaxial rotational diffusion were used in the fitting procedure. The results of the fitting show that a preference should be given to the 120†-jump model. A comparison with an IR profile study was also made. Both the existence of 120°-jumps and the discontinuity in the correlation times observed at the phase transition can qualitatively be explained by the Bates and Stevens picture.