Electron paramagnetic resonance basic principles

Electron paramagnetic resonance (EPR) and NMR spectroscopy are quite similar in their basic principles and in experimental techniques. They detect different phenomena and thus yield different information. The major use of EPR spectroscopy is in the detection of free radicals which are uniquely characterised by their magnetic moment that arises from the presence of an unpaired electron. Measurement of a magnetic property of a material containing free radicals, like its magnetic susceptibility, provides the concentration of free radicals, but it lacks sensitivity and cannot reveal the structure of the radicals. Electron paramagnetic resonance spectroscopy is essentially free from these defects. 

Basic Principles of Electron Paramagnetic Resonance Spectroscopy... 

To place these developments in perspective, some account will be given of the invention of magnetic resonance methods for condensed matter and of the various types of apparatus that were available, especially for MR where there has been substantial improvement in instrumentation with time. (We shall abbreviate nuclear magnetic resonance by NMR" and electron paramagnetic resonance by "EPR". We prefer the latter designation to electron spin resonance, because electron orbital as well as spin moments may be involved.) Since many readers may not be familiar with the principles of magnetic resonance, qualitative explanations of basic aspects are included. Emphasis will be on work in the United States, but some contributions from elsewhere will be mentioned. 

Basic Principles of Plasma Riysics A Statistical Approach, 1973 (2nd printing, with revisions, 1980) The Physical Principles of Electron Paramagnetic Resonance, 2nd Edition, completely revised, enlarged, and reset, 1973 [cf. (9)—1 st edition... 

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