The Nobel Prize in Physics 1981
Born: 11 March 1920, Dordrecht, the Netherlands
Died: 5 September 2017, Tucson, AZ, USA
Affiliation at the time of the award: Harvard University, Cambridge, MA, USA
Prize motivation: "for their contribution to the development of laser spectroscopy."
Prize share: 1/4
Electrons in atoms and molecules have fixed energy levels, according to the principles of quantum physics. When there are transitions among different energy levels, light with certain frequencies is emitted or absorbed. This allows atoms and molecules to be analyzed with the help of the absorbed light's spectrum. In the 1960s Nicolaas Bloembergen used laser light, which has waves in phase and of the same wavelength, to determine energy levels with great precision. By coordinating three laser waves, a fourth laser wave was created, and a larger part of the spectrum could be covered.