DYNAMICS OF BROMOHEXADECANE AND BROMODECANE CHAINS INCLUDED IN AN ORGANIC MATRIX - AN INCOHERENT QUASI-ELASTIC NEUTRON-SCATTERING STUDY

The nitroxide C9H16NO2 (tano) forms channel inclusion compounds with a large range of linear chains or slightly branched molecules. All of t hem present disorder phenomena of the guest chains in the channels of the structure, but also of the host matrix molecules from one chiral f orm to the other. The evolution of this disorder as a function of the temperature is accompanied by one or two phase transitions above 100 K . The incoherent quasielastic neutron scattering (IQNS) technique was used to study the motion of the tano molecules for the tano/1-bromohex adecane and the tano/1-bromodecane systems in their low, intermediate and high temperature phases. The experiments were carried out on a pol ycrystalline sample at the Institut Laue-Langevin in Grenoble using th e time-focusing time-of-flight spectrometer IN6 with a temperature ran ging from 103 K to 300 K. The motion of the guest chains also was show n. The results are examined in terms of the general model proposed in an earlier IQNS study of other tano/alkane compounds with shorter incl uded chains and the original features associated with the chain length are discussed.