Chemical characterization electron spin resonance

This volume covers a wide range of fundamental topics in coal maceral science that varies from the biological origin of macerals to their chemical reactivity. Several chapters report novel applications of instrumental techniques for maceral characterization. These new approaches include solid l3C NMR, electron spin resonance, IR spectroscopy, fluorescence microscopy, and mass spectrometry. A recently developed method for maceral separation is also presented many of the new instrumental approaches have been applied to macerals separated by this new method. The contributions in this volume present a sampling of the new directions being taken in the study of coal macerals to further our knowledge of coal petrology and coal chemistry. 

Intermediates in the radiation chemistry of high polymers include ions and trapped electrons, radicals and excited states. Free radicals trapped after irradiation have been studied mainly by electron spin resonance (ESR) and in some cases by chemical methods and by ultraviolet or infrared spectroscopy. The detection of free radicals during radiolysis has been performed by pulse radiolysis and also by ESR. Trapped ions and radical-ions were characterized by absorption spectroscopy and thermoluminescence while pulse radiolysis allows their detection during irradiation. Excited states, owing to their very short lifetime, could be observed only by pulse radiolysis or by the measurement of the luminescence spectrum and decay time during steady irradiation. 

Characterization of the chemical structure of highly cross-linked polymers, and of the chemical changes that accompany degradation processes, relies on spectroscopic methods. Solid-state nuclear magnetic resonance techniques have the potential to allow a more detailed characterization than before possible of the chemical environment and structure of chemical crosslinks in elastomers and thermoset epoxies. Degradation processes in cross-linked systems have been studied by using infrared spectroscopy, solid-state NMR, and electron spin resonance. 

The measuring of radio-frequency-induced transmissions between magnetic energy levels of atomic nuclei. It is a powerful method for elucidating chemical structures, such as by characterizing material by the number, nature, and environment of the hydrogen atoms present in a molecule. This technique is used to solve problems of crystallinity, polymer configuration, and chain structure. See chemistry, analytical electron spin resonance spectroscopy thermal analysis. 

Characterization of Phenalenyl Radicals in Various Fuel Samples. Fuel, Vol. 69, No. 2, (February 1990), pp. 203-206, ISSN 0016-2361 Sogo, P. B., Nakazaki, M Calvin, M. (1957). Free Radical from Peiinaphthene. Journal of Chemical Physics, Vol. 26, No. 5, (May, 1957) pp. 1343-1345, ISSN 0021-9606 Uesugi, A. Ikeya, M. (2001). Electron Spin Resonance Measurement of Organic Radicals in Petroleum Source Rock Containing Transition Metal Ions. Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes Reoiew Papers. Vol. 40, No. 4A, (April 2001), p. 2251-2254, ISSN 0021 922... 

Davidson et characterized perflurotetradecahydrophenanthroline oligomers using a combination of nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy for chemical analysis and time of flight secondary ion mass spectrometry, infrared spectroscopy and ultraviolet-visible spectroscopy. 

Relaxation measurements provide a wealth of information both on the extent of the interaction between the resonating nuclei and the unpaired electrons, and on the time dependence of the parameters associated with the interaction. Whereas the dipolar coupling depends on the electron-nucleus distance, and therefore contains structural information, the contact contribution is related to the unpaired spin density on the various resonating nuclei and therefore to the topology (through chemical bonds) and the overall electronic structure of the molecule. The time-dependent phenomena associated with electron-nucleus interactions are related to the molecular system, and to the lifetimes of different chemical situations, for the resonating nucleus. Obtaining either structural or dynamic information, however, is only possible if an in-depth analysis of a series of experimental results provides sufficient data to characterize the system within the theoretical framework discussed in this chapter. 

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