Isidor Isaac Rabi
Born: 29 July 1898, Rymanow, Austria-Hungary (now Poland)
Died: 11 January 1988, New York, NY, USA
Affiliation at the time of the award: Columbia University, New York, NY, USA
Prize motivation: "for his resonance method for recording the magnetic properties of atomic nuclei"
Field: nuclear physics
Prize share: 1/1
Protons and neutrons in nuclei act as small rotating, spinning magnets. Atoms and molecules therefore align in a magnetic field. In 1938 Isidor Rabi sent a beam of molecules through a magnetic field. When the beam was exposed to radio waves, the spin direction could be changed, but only in certain steps according to quantum mechanics. When returning to the original spin position, electromagnetic radiation was emitted with a frequency characteristic of the particular atom or molecule.