Rudolf L. Mössbauer (1929–2011)

Abstract

W hen Rudolf Mössbauer found in 1957 that γ-rays emitted by iridium-191 could be absorbed by a target of the same isotope without any loss of energy, it was soon obvious that he had discovered a new basis for spectroscopy. Just four years later, at the age of 32, he was awarded the Nobel Prize in Physics. Now named after him, Mössbauer spectroscopy is applied in fields ranging from chemistry to conservation. It is ideal for very fine-resolution work, such as determining the shift of spectral lines in Earth's gravitational field. It has even been used beyond Earth-to analyse the composition of rocks on Mars. Born in 1929 in Munich, Germany, Mössbauer was a talented piano player but decided to study physics at the Technical Institute of Munich (now the Technical University of Munich). His prizewinning discovery emerged from his PhD work investigating γ-ray absorption, done between 1955 and 1958 under Heinz Maier-Leibnitz at the Max Planck Institute for Medical Research in Heidelberg. In 1960, he moved to the California Institute of Technology (Caltech) in Pasadena, and received the Nobel prize a year later. But he didn't stay in America for long, moving back to the Technical Institute of Munich in 1964. The Bavarian government was willing to pay a high price for his return-a new physics building and ten professorships. But the gain for physics in Germany was tremendous. Mössbauer's new department brought a blast of fresh air to Munich and enhanced the scientific climate nationwide. Several German scientists who worked in the United States came back to Germany in what was called the 'second Mössbauer effect'. Mössbauer remained in Munich until his retirement in 1997. Between 1972 and 1975, he took leave to serve as director of the Laue-Langevin Institute in Grenoble, France. The power of Mössbauer spectroscopy stems from two facts. Nuclei bound in a solid (a crystal, glass or viscous liquid) are unaffected (with some probability) by recoil when they emit or absorb γ-radiation, and so do not gain or lose energy. Moreover, the frequency range of these γ-rays-the natural