M. Mehring – författare
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3 produkter
3 produkter
861 kr
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The field of Nuclear Magnetic Resonance (NMR) has developed at a fascinating pace during the last decade. It always has been an extremely valuable tool to the organic chemist by supplying molecular "finger print" spectra at the atomic level. Unfortunately the high resolution achievable in liquid solutions could not be obtained in solids and physicists and physical chemists had to live with unresolved lines open to a wealth of curve fitting procedures and a vast amount of speculations. High resolution NMR in solids seemed to be a paradoxon. Broad structure less lines are usually encountered when dealing with NMR in solids. Only with the recent advent of mUltiple pulse, magic angle, cross-polarization, two-dimen sional and multiple-quantum spectroscopy and other techniques during the last decade it became possible to resolve finer details of nuclear spin interactions in solids. I have felt that graduate students, researchers and others beginning to get involved with these techniques needed a book which treats the principles, theo retical foundations and applications of these rather sophisticated experimental techniques. Therefore I wrote a monograph on the subject in 1976. Very soon new ideas led to the developement of "two-dimensional spectroscopy" and "multiple-quantum spectroscopy", topics which were not covered in the first edition of my book. Moreover an exponential growth of literature appeared in this area of research leaving the beginner in an awkward situation of tracing back from a current article to the roots of the experiment.
Electronic Properties of Polymers and Related Compounds
Proceedings of an International Winter School, Kirchberg, Tirol, February 23 – March 1, 1985
Häftad, Engelska, 2011
1 075 kr
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At the International Winter School on "Electronic Properties of Polymers and Related Compounds" particular attention was paid to a very new and special field in polymer research. It is concerned with the study of the electronic structure of polymers and with physical and chemical properties directly re lated to this structure. In particular, tutorial and research contributions on electrical, electrochemical, optical, magnetic, lattice dynamical and structural properties were presented. In addition, review reports on related topics such as charge transfer complexes and linear-chain compounds (transi tion-metal trichalcogenides) were included. In two discussion meEjtings, the special role of polyacetylene and possible present and future applications of the electronic properties of polymers, as e.g. conductors or as electrodes in electrochemical cells, were elucidated. The electronic properties of polymers cover a wide range of research problems which are of particular interest for polymers with a 1T-electron system. Thus, a great part of the work presented was concerned with conjuga ted systems. Additional presentations dealt with other systems such as bio polymers, photopolymers or electrets, which are of significant scientific and technical importance. It was demonstrated how their electronic proper ties are increasingly being investigated from a fundamental point of view by applying known concepts of snlid-state science.
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Manipulation and Dilution Tools for Ruling Abundant Species "NMR is dead" was the slogan heard in the late 1960s at least among physicists, until John S. Waugh and his co-workers initiated a series of new NMR experiments, which employed the coherent modulation of interactions by strong radiofrequency fields. A wealth of new phenomena was observed, which are summarized in the introduction for the convenience of the unbiased reader, whereas Section 2 collects the basic spin interactions observed in solids. Line-narrowing effects in dipolar coupled solids by the application of multiple pulse experiments are extensively discussed in Section 3. Numerous extensions of the basic Waugh, Huber, and Haeberlen experiment have been developed by different groups and have been applied to the nuclei IH, 9Be, 19F, 27Al, 31p, 63CU in solids. Application of this technique to a variety of systems is still in progress and should reveal interesting insights into weak spin interactions in solids. It was soon realized that rare spins could be used as monitors for molecular fields in the solid state; however, rare spin observation is difficult because of the small signal-to-noise ratio. Pines, Gibby, and Waugh introduced a new concept of cross-polarization, based on ideas of Hahn and co-workers, which allows the detection ofrare spins with increased sensitivity. The dynamics involved are treated in detail. Other sections merely list results obtained by the techniques described and demonstrate their usefulness in the investigation of dynamical problems in molec ular and solid state physics.