Deuteron NMR studies

In deuteron NMR studies of the diffusion of benzene within zeolites it was found that the pre-exponential factor for the correlation time was inversely proportional to the number of available sites to which a molecule could jump. The pre-exponential factor is the limiting value of the correlation time as temperature tends to infinity. In previous work, the above findings for zeolites have been generalised to so-called "amorphous structures which exhibit the property of self-similarity. It was assumed that the pre-exponential factor for the correlation time was inversely proportional to the number of adsorption sites contained within a limiting length scale, is a parameter of the model determined... 

Pschom U, Spiess HW, Hisgen B, Ringsdorf H (1986) Deuteron NMR study of molecular order and motion of the mesogenic side groups in liquid-crystalline polymers. Macromol. Chem. 187 2711 see also Sjxess HW (1985) Deuteron NMR — A new tool for studying chain mobility and orientation in polymers. Adv. Polymer Sci., 66 23... 

Another deuteron NMR study of T f of PEO in blends with PVAc shows the same behavior (Zhao et al., 2008). Throughout the range —9 > log (t< / A) -11.8, the Taf of 2%, and 50% PEO differ by about half a decade. The difference between Tq,/ of 2% and 100% PEO increases with the increase of Taf, but no more than about a decade in the same range. The effect seems general. 

The first term is the result of translational diffusion induced rotation in the limit 0), T 1 whereas the second term, which is frequency independent includes the contributions of both (7 j p)buik, and of the crossrelaxation to the polymer. The time during which a liquid crystal molecule remains attached to the surface has been estimated as Tg 8 10" s [207]. Deuteron NMR studies... 

J. Hirschinger, W. Kranig, and H. W. Spiess, A deuteron NMR study of axial motion and side chain conformation in the mesophase of discotic liquid crystal main-chain polymers. Colloid Polym. Sci. 269 993-1002 (1991). 

Deuteron NMR — A new Tool for Studying Chain Mobility and Orientation in Polymers... 

Pulsed deuteron NMR is described, which has recently been developed to become a powerftd tool for studying molectdar order and dynamics in solid polymers. In drawn fibres the complete orientational distribution function for the polymer chains can be determined from the analysis of deuteron NMR line shapes. By analyzing the line shapes of 2H absorption spectra and spectra obtained via solid echo and spin alignment, respectively, both type and timescale of rotational motions can be determined over an extraordinary wide range of characteristic frequencies, approximately 10 MHz to 1 Hz. In addition, motional heterogeneities can be detected and the resulting distribution of correlation times can directly be determined. 

Komfield J.A., Spiess H.W., Nefzger H., Hayen H., and Eisenbach C.D. Deuteron NMR measurement of order and mobility in the hard segments of a model polyurethane, Macromolecules, 24, 4787, 1991. Meltzer A.D., Spiess H.W., Eisenbach C.D., and Hayen H. Motional behaviour within the hard domain of segmented polyurethane A NMR study of a triblock model system. Macromolecules, 25, 993, 1992. 

Translation and reorientation of CD4 molecules in zeolites as studied by deuteron NMR relaxation... 

Nuclear magnetic resonance provides means to study molecular dynamics in every state of matter. When going from solid state over liquids to gases, besides mole- cular reorientations, translational diffusion occurs as well. CD4 molecule inserted into a zeolite supercage provides a new specific model system for studies of rotational and translational dynamics by deuteron NMR. 

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