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Nuclear relaxation phenomena have been studied in systems in which extremely fast modulations of the perturbing interactions by internal motions exist. A comparison of the spin-lattice relaxation time T1 and the spin-spin relaxation time T2 has been of particular interest, as well as an investigation of the various possible relaxation mechanisms, including the well-known Fermi contact hyperfine interaction. Comprehensive calculations of relaxation times for all important perturbing interactions have been made on the basis of the Redfield theory. Experiments measured both T1 and T2, and examined the dependence of the relaxation times on temperature, isotopic abundance, solute concentration, impurity content, and so on. Whenever necessary, Knight shifts were measured and the results were used in combination with the relaxation time data. All measurements were made with a coherent pulsed nuclear resonance apparatus, and the sample temperature was controlled by means of hot air oven. (Author).
Electron spin relaxation has established itself as an important experimental method for studying the details of molecular motion in liquids, and as a harsh testing ground for theoreticians. The theo retical difficulties are connected with the complexity of the mole cular motion, and the theoretical interest lies not only in its im portant consequences for the interpretation of experiments, but also in the fascination of a system in which a well-defined quantum me chanical component is in interaction with a complex quasi-classical environment. It is because the theories are concerned with such dissimilar but connected systems that the techniques involved are so numerous. Many of the standard manipulations of quantum mechanics must be brought to bear, and at the same time they must be combined with statistical techniques which are often of considerable sophis tication. The purpose of this volume is to present a survey of these techniques and their application to spin relaxation problems. No single volume can be exhaustive, but we believe that the contri butions to this volume are sufficiently broad to show how those who are concerned with spin relaxation problems think about the subject and circumvent, or expose, its difficulties. The first few Chapters (I-V) review the basic quantum mechani cal and statistical manipulations which are often used.
Properties of the conduction electron system in the liquid binary alkali metal alloys were investigated. Experimental values are given of the Knight shifts of both constituents of a binary alloy, when possible, for those alloys not previously studied. As the binary alloys of sodium, potassium, rubidium and cesium with one another are completely miscible in the liquid state, the entire concentration range for all alloys was covered. The Knight shifts were then interpreted to give the electron spin susceptibilities of those alkali metals for which the spin susceptibility has not yet been reported. These susceptibilities were then used to obtain experimental values of other interesting quantities. Measured values of the density of states at the Fermi surface for the pure metals were obtained. Finally these measured densities of states and the measured specific heats were combined to give measured values of the electron-phonon interaction contribution to the thermal effective mass of the electrons in the pure metals.
The Alloy Data Center, part of the National Standard Reference Data System, has two primary functions. One is to stimulate cooperation and coordination among the existing data centers in the area of the physical properties of well characterized alloys. The final data generated by these centers for publication should be consistent with one another where correlation or possible overlap exists. The other purpose is the collection (from publications as well as private communications), evaluation, and publication of data in some areas where special competence exists in the Alloy Physics Section. Of interest to the center are metals, semimetals, intermetallic compounds, and alloys. Excluded are those materials which have ill-defined constitutions and heat treatments. An automated system was developed to meet the bibliographic needs of the center. This system will be described as well as the specific properties of interest. The system presently contains a complete annotated file dealing with NMR Knight shift measurements. The soft X-ray spectroscopy compilation is being kept up-to-date with the same system. (Author).