Nuclear magnetic resonance first detection

Nuclear magnetic resonance of protons was first detected in 1946 by Edward Purcell (Harvard) and by Felix Bloch (Stanford) Purcell and Bloch shared the 1952 Nobel Prize in physics... 

Since the earliest days of Nuclear Magnetic Resonance (NMR), it has been clear (1-10) that relaxation mechanisms were to play an important role in all its applications. In fact, even the first detection of an NMR signal (11-12) was delayed (12-13) by several years because the chosen compounds had, unfortunately, excessively long relaxation times. 

Analytical methods for aluminum can be divided into those that give information about its localization, and those that inform about its quantity. In the first group are nuclear techniques, involving the Al-26 tracer and the Al-27 nuclear magnetic resonance (NMR). In the second group is the well-established technique for aluminum quantification, ETAAS, and a new generation of chromatographic separations coupled with spectrometric detection that allow compartmentalized quantification, the hyphenated systems. 

In terms of characterizing the microstrac-ture of polymer chains, the two most useful techniques are infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectroscopy. Commercial infrared spectrometers were introduced after the end of the second world war and quickly became the workhorse of all polymer synthesis laboratories, providing a routine tool for identification and, to a certain degree, the characterization of microstructure (e.g., the detection of short chain branches in polyethylene). In this regard it can no longer compete with the level of detail provided by modem NMR methods. Nevertheless, IR remains useful or more convenient for certain analytical tasks (and a powerful tool for studying other types of problems). So here we will first describe both techniques and then move on to consider how they can be applied to specific problems in the determination of microstructure. 

Nuclear magnetic resonance studies revealed that normal prothrombin contains y-carboxyglutamate, a formerly unknown residue that evaded detection because its second carboxyl group is lost on acid hydrolysis during amino acid analysis. The abnormal prothrombin formed subsequent to the administration of anticoagulants lacks this modified amino acid. In fact, the first 10 glutamate residues in the amino-terminal region of prothrombin... 

The direct detection of radiation induced crosslinks in polyethylene has been a major goal of radiation chemists for many years. It was recognized as early as 1967 that solution 13c nuclear magnetic resonance (NMR) spectroscopy could be used to detect structures produced in polymers from ionizing radiation. Fischer and Langbein(l) reported the first direct detection of radiation induced crosslinks (H-links) in polyoxymethylene using 13c NMR. Bennett et al.(2) used 13c NMR to detect radiation induced crosslinks in n-alkanes irradiated in vacuum in the molten state. Bovey et al.(3) used this technique to identify both radiation induced H-links and long chain branches (Y-links) in n-alkanes... 

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