The Nobel Prize in Physics 1952
Felix Bloch, E. M. Purcell
Born: 23 October 1905, Zurich, Switzerland
Died: 10 September 1983, Zurich, Switzerland
Affiliation at the time of the award: Stanford University, Stanford, CA, USA
Prize motivation: "for their development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith"
Field: nuclear physics
Protons and neutrons in nuclei act as small rotating, spinning magnets. Atoms and molecules therefore align in a magnetic field. When exposed to radio waves they can change direction, but only in certain steps according to quantum mechanics. When returning to the ground, state atoms emit electromagnetic radio waves with frequencies characteristic for different elements and isotopes. Felix Bloch and Edward Purcell developed in 1946 methods for precision measurements used to study the composition of different materials.