On the suggestion ofRichard Feynman, Mössbauer was invited in 1960 toCaltech in the USA, where he advanced rapidly from research fellow to senior research fellow; he was appointed a full professor of physics in early 1962. In 1964, his alma mater, theTechnical University of Munich (TUM), convinced him to go back as a full professor. He retained this position until he becameprofessor emeritus in 1997. As a condition for his return, thefaculty of physics introduced a "department" system. This system, strongly influenced by Mössbauer's American experience, was in radical contrast to the traditional, hierarchical "faculty" system of German universities, and it gave the TUM an eminent position in German physics.[citation needed]
In 1972, Rudolf Mössbauer went to Grenoble to succeed Heinz Maier-Leibnitz as the director of theInstitut Laue-Langevin just when its newly built high-fluxresearch reactor went into operation. After serving a five-year term, Mössbauer returned to Munich, where he found his institutional reforms reversed by overarching legislation. Until the end of his career, he often expressed bitterness over this "destruction of the department." Meanwhile, his research interests shifted toneutrino physics.
Mössbauer was regarded as an excellent teacher. He gave highly specialized lectures on numerous courses, includingNeutrino Physics,Neutrino Oscillations,The Unification of the Electromagnetic and Weak Interactions andThe Interaction of Photons and Neutrons With Matter. In 1984, he gave undergraduate lectures to 350 people taking the physics course. He told his students: “Explain it! The most important thing is that you can explain it! You will have exams, there you have to explain it. Eventually, you pass them, you get your diploma and you think, that's it! – No, the whole life is an exam, you'll have to write applications, you'll have to discuss with peers... So learn to explain it! You can train this by explaining to another student, a colleague. If they are not available, explain it to your mother – or to your cat!”
Mössbauer married Elizabeth Pritz in 1957. They had a son, Peter and two daughters Regine and Susi.[3][4] They divorced in 1983, and he married his second wife Christel Braun in 1985.[4][citation needed]
