LOW-FREQUENCY EXCITATIONS OF AROMATIC-MOLECULES IN THE SOLID-STATE

We have used inelastic and near-elastic neutron scattering to investigate the motion of aromatic molecules in the solid state. In particular we have studied benzene, toluene, ethylbenzene, 1,3,5-trifluorobenzene and the van der Waals adduct formed between benzene and hexafluorobenzene, C6H6:C6F6. From the angle dependence of the inelastic scattering we have determined the mean squared amplitude of oscillation of the protons responsible for the scattering at a number of sample temperatures. From experiments involving near-elastic or quasi-elastic neutron scattering we have measured the change of linewidth induced in the neutron beam during the scattering process relative to a fixed energy window, this can also be used, in some cases, as a measure of the mean square amplitude of scatterer oscillation.