Proton NMR studies

NMR in solution, primarily proton and carbon, is one of the most extensively used tools for materials characterisation. The importance of these methods is due in part to the extreme sensitivity of the NMR signals to small changes in the chemical structure of polymers, such as those that arise from polymer stereochemistry, defects and other types of microstructure. 

The power of proton NMR has been illustrated with stereochemical examples. The spectrum is also sensitive to other types of defects, including branches. 

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Dielectric Behavior of Adsorbed Water. Determination of the dielectric absorption of adsorbed water can yield conclusions similar to those from proton NMR studies and there is a considerable, although older literature on the subject. Figure XVI-7 illustrates how the dielectric constant for adsorbed water varies with the frequency used as well as with the degree of surface coverage. A characteristic relaxation time r can be estimated... 

The entropy value of gaseous HCl is a sum of contributions from the various transitions summarized in Table 4. Independent calculations based on the spectroscopic data of H Cl and H Cl separately, show the entropy of HCl at 298 K to be 186.686 and 187.372 J/(mol K) (44.619 and 44.783 cal/(mol K), respectively. The low temperature (rhombic) phase is ferroelectric (6). SoHd hydrogen chloride consists of hydrogen-bonded molecular crystals consisting of zigzag chains having an angle of 93.5° (6). Proton nmr studies at low temperatures have also shown the existence of a dimer (HC1)2 (7). 

The main uses of deuterium are in traeer studies to follow reaetion paths and in kinetie studies to determine isotope effeets. " A good diseussion with appropriate referenees is in Comprehensive Inorganic Chemistry, Vol. 1, pp. 99-116. The use of deuterated solvents is widespread in proton nmr studies to avoid interferenee from solvent hydrogen atoms, and deuteriated eompounds are also valuable in struetural studies involving neutron diffraetion teehniques. 

Besha, K., Key, C, Glimcher, M., Schimizu, M. and Griffin, R.G. 1990 Solid state carbon-13 and proton NMR studies of carbonate-containing calcium phosphates and enamel. Journal of Solid State Chemistry 84 71-81. 

Ni Dhubhghaill, O.M., Sadler, P.J. and Tucker, A. (1992) Drug-induced reactions of bovine serum album proton NMR studies of gold binding and cysteine release. Journal of the American Chemical Society, 114, 1117-1118. 

IN VIVO PROTON NMR STUDIES IN SKELETAL MUSCULATURE 51 Table 4. Characteristics of the study population... 

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