Photo from the Nobel Foundation archive.
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."
Prize share: 1/2
Felix Bloch was born in Zurich, Switzerland, the son of a merchant, and studied at ETH and elsewhere. When the Nazis took power in 1933, he left Europe to work at Stanford University. After becoming an American citizen, he worked on atomic energy in Los Alamos during World War II and later on radar at Harvard University. Immediately after the war, he did his Nobel Prize-winning work at Stanford. He became the first head of CERN outside Geneva in 1954-1955. Felix Bloch was married and had four children.
Protons and neutrons in nuclei act like small, rotating magnets. Atoms and molecules therefore align in a magnetic field. Radio waves can disturb their direction of rotation, but only in certain stages, in accordance with quantum mechanics. When the atoms return to their original positions, they emit electromagnetic radio waves with frequencies characteristic of different elements and isotopes. In 1946, Felix Bloch and Edward Purcell developed methods for precise measurement, making it possible to study different materials' compositions.