Photo from the Nobel Foundation archive.
Rudolf Ludwig Mössbauer
Born: 31 January 1929, Munich, Germany
Died: 14 September 2011, Grünwald, Germany
Affiliation at the time of the award: Technical University, Munich, Federal Republic of Germany , California Institute of Technology (Caltech), Pasadena, CA, USA
Prize motivation: "for his researches concerning the resonance absorption of gamma radiation and his discovery in this connection of the effect which bears his name."
Prize share: 1/2
According to the principles of quantum physics, the atomic nucleus and surrounding electrons can have only fixed energy levels. When there are transitions among energy levels in the atomic nucleus, high-energy photons known as gamma rays are emitted and absorbed. In a gas a recoil effect occurs when an atom emits a photon. In 1958 Rudolf Mössbauer discovered that the recoil can be eliminated if the atoms are embedded in a crystal structure. This opened up opportunities to study energy levels in atomic nuclei and how these are affected by their surroundings and various phenomena.