Pressure dependence of the dynamics of an organic inclusion compound investigated by incoherent quasielastic neutron scattering

The nitroxide (referred to as tano) forms channel inclusion compounds with linear hydrocarbons. At room temperature, both tano and chain molecules are dynamically disordered. When the temperature is decreased, one phase transition is observed. The pressure dependence of the temperature of transition and the evolution of the individual motions have been studied by incoherent quasielastic neutron scattering in the case of a tano - octane system. The transition temperature increases with the pressure with a slope . The transition mechanism is connected to the lock-in of both tano (interconversion) and chain (reorientation) molecules, as a result of strong correlations between host and guest substructures. A residual disorder persists in the low-temperature phase confirming that all the tano molecules are not dynamically equivalent.