Relaxation spectrum hybrid

As discussed in Sect. 8, the relaxation spectrum of a dendrimer differs considerably from that of a polymer chain. Due to the symmetry of the dendrimer many of its eigenvalues (relaxation times) are degenerate. This contrasts with the relaxation times of the Rouse chain which are all distinct (nondegenerate), see Sect. 4. Therefore, considering hybrid structures formed... 

Good agreement with experimental viscoelastic measurements on several helical polymers has been obtained with an empirical hybrid relaxation spectrum in which a separate rotational mode (relaxation time tq) has been added to a set of mechanisms attributed to internal motions and spaced in accordance with the Zimm spectrum (tj, T2,. . The appropriate equations for [(/ ] and are as follows ... 

FIGURE 31. Typical data set for measurement of the spin-lattice relaxation times of the sp2-hybridized carbon atoms of, 6-carotene at 11.7 T. The chemical shift values are shown across the bottom of the figure. The t-value for each spectrum is the delay time in the inversion-recovery pulse sequence. Reprinted with permission from Reference 49. Copyright (1995) American Chemical Society... 

Figure 18. The absorption (a) and loss (b) spectrum of CH3F at T = 133 K. Solid and dashed lines refer, respectively, to rigorous and the hybrid-model versions of the hat-flat model, circles do to experiment. The vertical line marks the frequency of relaxational loss peak.

Several lines of evidence showed that the chemical composition and functional integrity of the disaccharide unit remained intact after attachment to the QD. Figure 3 shows the NMR spectra of the free thiol 3 and the hybrid TrMAA-CdTe QDs in D2O. The broad peaks in the spectrum of the QDs are a result of increased relaxation rates due to effective molecular weight (>50 KDa)... 

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