| Abstract: | The 13C NMR relaxation functions are calculated for the case of restricted rotational diffusion of a C? H dipole pair about an internal rotational axis. The model is applied to the interpretation of recent 13C experiments of polystyrene in a region where the relaxation of all C atoms of the phenyl ring exhibits the same temperature coefficient. It is concluded that the velocity of the phenyl group motion may be overestimated if complete rotation is assumed. By means of the model of restricted internal rotation one finds D/D0<0,1 for the ratio of internal and mean segmental rotational diffusion constants. |
