Polymers subgroup motion

Luminescence of Probe Molecules. These studies permit evaluation of polymer properties. In particular, measurement of the relative Intensities of fluorescence of a probe molecule polarized parallel to and perpendicular to the plane of linearly polarized exciting radiation as a function of orientation of a solid sample yields Information concerning the ordering of polymer chains. In solution, similar polarization studies yield Information on the rotational relaxation of chains and the viscosity of the microenvironment of the probe molecule. More recently, the study of luminescence Intensity of probe molecules as a function of temperature has been used as a method of studying transition temperatures and freeing of subgroup motion in polymers. 

We discuss under this heading the use of fluorescence polarization methods to study the order In polymers, particularly In drawn fibrous materials and, by association, the use of such ordered systems to study fundamental details of the luminescence of probe molecules, the use of polarization methods to study rotational motion In polymers In solution, and the temperature dependence of luminescence as a probe of subgroup motion. 

Different spectral domains reflect motions of individual subgroups of a molecule. Assignments can be made by comparison with the IR and Raman spectra of simple bases, nucleosides, nucleotides, and polymers (Tsuboi, 1969). Isotopic substitution by N or 0, which causes selective absorption shifts, has also been employed (Miles, 1964 Tsuboi et ah, 1968). 

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