Molecular motion in the van der Waals solid C

From a study of the quasielastic neutron scattering of solid C6H6:C6F6 at temperatures between 200 and 280K we found it necessary to consider two types of molecular motion to fully interpret the measurements, a six-fold rotation of the protonaceous partner and a translational diffusion of the dimer. We find that the rate of rotational reorientation of the benzene partner and the rate of diffusion of the dimer change dramatically with temperature. This rate of change of the dynamical processes is seen to correlate with the position of phase transitions previously observed in this material. We have performed an Arrhenius analysis of the rotational and translational motions and the exponential and pre-exponential parameters are given, for the different phases, in the text