Neutron spectrometry and numerical simulations of low-frequency internal vibrational in solid xylenes

Vibrational densities of states of solid xylenes were determined from the inelastic neutron scattering spectra measured on the NERA spectrometer at the IBR-2 pulsed reactor. These spectra were used to test the semi-empirical quantum-chemistry calculations of internal vibrations of xylene molecules with differently deuterated sub-units. Rotations of methyl groups were found to be strongly affected by intermolecular interactions in the crystals and mixed with phenyl ring deformations.