Mössbauer, Rudolf (Ludwig) (1929– )

German physicist who was awarded the Nobel Prize for Physics in 1961 for his discovery in 1958 that under certain conditions an atomic nucleus can be stimulated to emit very sharply defined beams of gamma rays – a phenomenon that became known as the Mössbauer effect.

Mössbauer was born in Munich, studied at the Munich Institute of Technology, and did postgraduate research in Heidelberg at the Max Planck Institute. In 1960 he went to the USA and a year later became professor of physics at the California Institute of Technology, Pasadena. He remained in this position while simultaneously holding a professorship at Munich. Mössbauer began research into the effects of gamma rays on matter in 1953. The absorption of a gamma ray by an atomic nucleus usually causes it to recoil, so affecting the wavelength of the re-emitted ray. Mössbauer found that at low temperatures the nuclei do not recoil because they are tightly bound in the crystal lattice. This recoilless nuclear resonance absorption became known as the Mössbauer effect. The effect is exploited in Mössbauer spectroscopy, a useful tool in the study of the structure of solids.