Reprinted from the March 2004 edition of the Mössbauer Spectroscopy Newsletter, published as part of Volume 27, Issue 3 of the Mössbauer Effect Reference and Data Journal
Ursula Wagner in the radiochemistry laboratory in front of some of the thousands of pottery samples she has studied over the years. The picture was taken in 2000.
Fritz Wagner in the laboratory with two time-honoured Mössbauer cryostats, which date back to the 1960s but are still working fine. The picture was taken in 2000.
Fritz Wagner was born in 1937 and studied physics at the Technical University of Munich. In 1960 he was looking for a subject for his diploma thesis. Professor Heinz Maier-Leibnitz suggested the subject of resonant absorption of gamma rays that was to be supervised by his assistant, R. L. Mössbauer. Mössbauer was content to hear that his potential new student had a car and thus could drive to Garching, then a desolate place outside the reach of public transportation.
Within hours, Fritz Wagner was involved in his first Mössbauer measurements a tedious matter at the time, but this was to become better with the advent of multichannel analyzers and electromechanical velocity drives.
Fritz Wagner’s diploma thesis was on 170Yb and he used the then rather new Munich Research Reactor to make the 170Tm sources. His first major achievement in science was to arrange a major radioactivity spill, but he was forgiven and was allowed to continue with his thesis work. During this time he saw precious little of Rudolf Mössbauer, who soon left for Pasadena, though presumably not because of his student. But Mössbauer spectroscopy never let go of Fritz Wagner in the decades to come. He finished his Ph.D. thesis on the total reflection of the 169Tm gamma radiation with Maier Leibnitz and Paul Kienle in 1965.
Fritz Wagner with one of his students, Michael Karger, at the Second Seeheim Workshop on Mössbauer Sepectroscopy held at the Lufthansa Training Center at Seeheim, Germany, in 1983.
Ursula Wagner is a chemist who did her Diploma and Ph.D. theses at the Technical University of Munich in metal organic chemistry with E. O. Fischer, who won the Nobel Prize for his work in 1973. Her Ph.D. thesis was on hot atom chemistry with metal organic compounds, and she made use of the then new Munich Research Reactor in this work. After getting her Ph.D., she went to Brookhaven to continue this line of research with Garman Harbottle.
Ursula had her first encounter with Mössbauer spectroscopy as early as 1962 when, because of her education in metal organic chemistry, she became engaged in Mössbauer experiments on ferrocene and iron carbonyls together with Paul Kienle, Mike Kalvius, and Dr. Eicher.
Ursula Wagner in conversation with Rudolf Mössbauer in Munich in the 1970s at a dinner of the Carl Friedrich von Siemens Foundation.
She was back in Munich when Rudolf Mössbauer returned from CalTech and began to build up his group at the Technical University of Munich. Ursula became the person who ran the radiochemistry laboratory that was needed mainly to make sources for a variety of Mössbauer isotopes and materials to be studied by the Mössbauer method. With the reactor on site, the Munich group indeed excelled for years to come in work with many of the less common Mössbauer isotopes.
Among them were 139La, 141Pr, several isotopes of Er and Yb, and all those many Mössbauer isotopes of osmium, iridium, and platinum. A major effort was devoted to 99Ru and even 101Ru. A major, long time effort was on the use of 193Ir and 197Au. For these, with their short-lived source isotopes that had to be made at least once a week, the Munich Research Reactor next door turned out to be a real Godsend.
In 1971, Rudolf Mössbauer left Munich to become the director of the research reactor facility at Grenoble (ILL) and G. M. Kalvius came to Munich to replace him. When Fritz Wagner came back from a stay at Argonne National Laboratory, he joined Mike Kalvius’s group.
Ursula and Fritz were married in 1973, Fritz obtained his Habilitation in 1974 and soon afterwards became a Professor of Physics at the Physics Department of the Technical University of Munich. Towards the end of the 1970s, studies of metal hydrogen systems became a major field of research in Fritz’s group. Then, in 1979, a devastating fire nearly wiped out all of the Mössbauer equipment of the group. Luckily, the remaining equipment was patched together within days and measurements were resumed. Ursula continued her hot atom chemistry work, now also using Mössbauer spectroscopy.
In 1977 a turning point came in Ursula’s scientific career, when Josef Riederer, now director of the Rathgen Research Laboratory of the Archaeological Museums in Berlin, suggested that they use the Mössbauer capabilities available at the Physics Department to study some ancient Egyptian ceramics he was interested in. Ursula was fascinated by the idea and soon some promising results had been obtained. The subject developed into Ursula’s main field of research. The studies eventually turned away from Egyptian ceramics, when she began to work on Pre-Columbian Latin American pottery together with Izumi Shimada, the director of the Projecto Arqueologico de Sican. A young archaeologist, Rupert Gebhard, now a curator at the Archaeological State Collection in Munich, aroused her interest in Celtic ceramics from Central Europe and in particular from the oppidum of Manching in Bavaria. This was to become the second large field of ceramics research.
Ursula Wagner discussing her poster on ancient Egyptian ceramics with Jacques Danon at the ICAME in Kyoto in 1978.
Ursula combined Mössbauer spectroscopy with other techniques, foremost with neutron activation analysis for provenance studies of the ceramics. For this, the neighborhood of the Munich Research Reactor was once again of paramount importance.
The good times lasted until the summer of 2000, when the reactor was closed down because a new reactor had been built next to it and was supposed to become operational within no more than half a year. It became, in fact, critical for the first time in March of 2004, after a delay of about three years that was largely caused by political squabble. Ursula’s archeology project suffered somewhat from this, but with Mössbauer spectroscopy, combined with X-ray diffraction and thin section analysis, the archaeometry work is still going strong. Just recently, Ursula edited two special volumes of Hyperfine Interactions on Mössbauer spectroscopy in archaeology. This was a formidable task that kept both the Wagners busy for the past several years. This work is now finished, but there are already new plans for new projects and major publications of the many as-yet unpublished data.
Fritz’s research was also hard hit by the closing down of the reactor. In the 1990s it had largely turned to work with short-lived sources made at the Munich reactor. Gold played a major role in this, for instance with studies of gold ores containing only very small amounts of gold in chemically bound form, which had been of major interest in gold production and mineralogy. He and his group also studied gold in gold ruby glass and a number of catalysts. Catalysis quite generally became one of the other subjects that took Fritz’s fancy in the 1980s and ever since, with 99Ru, 193Ir, and 197Au as the mainstays and the more commonplace Mössbauer isotopes as mere additions.
Since the demise of the Munich Research Reactor, the catalyst and mineralogy research is confined to work with commercial sources, mainly 57Fe and 119Sn and 121Sb. This is a step backwards, since the Munich Mössbauer group was always proud of having the facilities and the know-how to do less common Mössbauer isotopes. But Mössbauer work is still going on in Munich, even though the number of workers has dwindled after the retirement of Mike Kalvius. The Wagners, however, still see Mössbauer spectroscopy as a fascinating method that gives beautiful results. They hang on and hope to do so for some time to come, perhaps even making use of the neutrons of the new FRM II reactor, when this becomes possible later this year.
Ursula and Fritz Wagner in front of the first Munich Research Reactor (FRM I), which became critical in 1957 and was closed down in the summer of 2000, and which profoundly influenced the scientific careers of both. The new reactor (FRM II), which became critical earlier this year, is hidden behind the old one in this picture, which was taken in May of 2004.
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