M. Bee et al., STRUCTURAL AND DYNAMICAL ASPECTS OF SOLID SULPHOLAN IN THE TEMPERATURE-RANGE 160-300 K .2. INCOHERENT QUASI-ELASTIC NEUTRON-SCATTERING STUDY, Physica. B, Condensed matter, 233(2-3), 1997, pp. 102-110
The dynamics of the sulpholan molecules in their high (I and II) and l
ow-temperature (III and IV) phases is studied using the incoherent qua
sielastic neutron scattering technique (IQNS). The experiments were ca
rried out on polycrystalline samples using the time-of-flight time-foc
ussing neutron spectrometer IN6 at the Institut Laue-Langevin in Greno
ble, with a temperature ranging from 160 to 298 K. The results are com
pared with the conclusions of previous NMR studies and examined in ter
ms of several models. It is shown that on the 10(-11) s time-scale acc
essible to the experiment, the molecular motions in the two high-tempe
rature phases essentially consist of a uniaxial rotation about the two
fold symmetry axis. In the low-temperature phase IV no quasielastic br
oadening was observed. Conversely, in the other low-temperature phase
III, restricted angular oscillations of molecules about their equilibr
ium positions are responsible for a distinct quasielastic broadening o
f the spectra, Another paper (paper I) deals with the structural aspec
ts of the phase transitions.