Rotational dynamics bulk phase

Three-Dimensional Model. On the other hand, if the interfacial layer is thick enough compared to the molecular size of SRIOI and if SRIOI molecules adsorbed on the interface are weakly oriented, the rotational motions of SRIOI take place in three dimensions, similar to those in a bulk phase. If this is the case, the contribution of the fluorescence with the excited dipole moment of SR 101 directed along the z-axis cannot be neglected, so that the time profile of the total fluorescence intensity must be proportional to / (0 + 2/i(t). Thus, fluorescence dynamic anisotropy is given by Equation (15), as is well known for that in a macroscopically isotropic system [10,13] ... 

First introduced to polymer chemistry by Schaefer and collaborators, CP-MAS spectroscopy has already yielded interesting results in both stractural and dynamic studies. The comparison of spectra in solution and in bulk permits identification of frozen conformations, distinction between spectra of crystalline and amorphous phases and measurement of the rate of several eonformational transitions. For example, the C spectrum of the poly(phenylene oxide), 74, in solution consists of five signals while the CP-MAS spectrum displays six. In the solid state the resonance of the aromatic CH appears split into two components. The phenomenon is attributed to the forbidden rotation of the benzene ring around the O. .. O axis, which makes the two carbon atoms indicated with an asterisk no longer equivalent. 

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