Discovery of Nuclear Magnetic Resonance: Rabi, Purcell, and Bloch

Abstract

The discovery of nuclear magnetic resonance (NMR) is a story from the history of science well worth examining by chemists. It is one example among many of the twentieth-century revolution of instrumentation in analytical chemistry developed by physicists. As such it illustrates the application of a discovery in one field of pure science (physics) first to another (chemistry) and later (as seen in other chapters in this volume) to the applied science of medicine. A look at its origins can, perhaps, give practicing chemists and chemistry students an added understanding and appreciation for a tool many use every day. NMR in bulk materials (that is, in solids, liquids, and solutions) is also a classic case of simultaneous discovery. The overarching external factor of World War II certainly influenced the expertise and networks that assisted this discovery, seeding it in more than one place. After a brief review of background information on the quantum concept of spin and its relative, magnetic moment, we examine the detection of NMR first in molecular beams (by Isidor Rabi and coworkers) and then in bulk matter independently by Edward Purcell and Felix Bloch, each with his own group of collaborators.