MOLECULAR-DYNAMICS OF GUEST MOLECULES IN THE CHANNELS OF UREA INCLUSION-COMPOUNDS INVESTIGATED BY MEANS OF IQNS SPECTROSCOPY

We present a brief discussion of the models describing the reorientati onal and translational motions of the guest molecules in the channels of urea inclusion compounds in their hexagonal phase. We discuss in pa rticular the methodology employed to analyse the incoherent quasi-elas tic neutron scattering profiles. Preliminary new results on the dynami cs of n-nonanoic acid guest molecules in urea are presented and compar ed to the results so far obtained on n-alkane/urea and alpha,omega-dib romoalkane/urea inclusion compounds. These results suggest that the tw o types of motions of n-nonanoic acid, translations and reorientations , are not correlated at the temperatures investigated.