Rotational diffusion in the rotator phase ofnhyphen;alkanes

摘要

From quasielastic neutron scattering experiments performed in the rotator phase ofnhyphen;alkanes (CnH2n+2), as a function of bothnand temperature, two types of rotational diffusion have been detected. Type B corresponds to a uniform rotational diffusion, whereas type A corresponds to a hindered rotation, probably limited to large amplitude oscillations. It is the first time that type A rotational diffusion, given by the orthorhombic symmetry phaseRI, is observed. On increasing the temperature it rapidly evolves towards the type B diffusion. Correlation times tgr; which seem to be rather independent of the phase type are of the order of 5times;10minus;12s.