Nuclear Magnetic Resonance Studies on Water and Ice
Nuclear magnetic resonance spectroscopy is, in essence, a semiclassical form of experiment. Thus, the separation of spectral energy levels is in a region such that the frequencies that cause transitions are produced by macroscopic oscillators (radiofrequency transmitters) as phase-coherent trains. Irradiation is achieved by antennas which may be physically arranged so as to cause the sample to be subject to waves with accurately known polarization. The signal-receiving antennas may be arranged so that the NMR signal has a known phase relation to the irradiating waves, and the signal is amplified by standard radiofrequency techniques. The method is semiclassical in so far as the interaction time of the irradiation with the system studied is concerned. For purely classical experiments, such as measurements of viscosity, the experiment is sensitive only on a very long time scale, say greater than 1 min. In purely nonclassical methods such as UV spectroscopy, the time scale is of the order of 10-15 sec. In the case of NMR measurements we are dealing with times ranging from 10-7 sec to very long times.
KeywordsNuclear Magnetic Resonance Study Magnetic Dipole Moment Quadrupole Coupling Constant Dielectric Relaxation Time Reorientation Time
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