Fritz Strassmann

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Friedrich Wilhelm "Fritz" Straßmann (born February 22, 1902 in Boppard , † April 22, 1980 in Mainz ) was a German chemist . He is one of the discoverers of nuclear fission .

education and study

Fritz Straßmann was born on February 22, 1902 as the ninth and last child of a middle court clerk in Boppard. His baptismal name "Friedrich Wilhelm" ( not uncommon during the imperial era ) was only used by his family and himself as a joke. Already during his school days in Düsseldorf, where his father was transferred in 1907, he was interested in chemistry; He therefore studied this subject after graduating from high school (1920) at the Technical University of Hanover . There he found access to the Hanover Musicians' Guild, learned to play the violin and met Maria Heckter and Irmgard Hartmann, his future wives, in these musically interested student groups of friends.

In 1929 he finished his studies with a doctorate in engineering. at Hermann Braune with the work: "On the influence of the saturation vapor concentration through the presence of compressed unideal gases (System I 2 - CO 2 )".

Research at the Kaiser Wilhelm Institute for Chemistry

Berlin

Straßmann remained as an assistant to his doctoral supervisor in Hanover, but when he was offered a scholarship from the Emergency Association of German Science for the Kaiser Wilhelm Institute (KWI) for Chemistry in Berlin-Dahlem in the same year , he accepted without hesitation. At 180 Reichsmarks , his salary was much lower than at the Technical University (400 Reichsmarks), but he was attracted by the new field of work, radiochemistry , under the well-known chemist Otto Hahn .

He learned to work with radioactive isotopes and their application to elucidate structural changes in individual substances and to determine the age of minerals and rocks. His thorough knowledge and skills in analytical chemistry came in very handy. His scholarship expired at the end of 1932, but he was allowed to continue working at the KWI unpaid.

In 1934 he was offered a position in the chemical industry, but declined because he would have had to join one of the National Socialist professional organizations; In 1935 he finally got an assistant position at the institute.

In 1937 he married the chemist Dr.-Ing. Maria Heckter. The son Martin was born in 1940.

Discovery of nuclear fission

Memorial plaque in memory of Fritz Straßmann and Otto Hahn on the Otto Hahn Building of the Free University of Berlin

In the autumn of 1934 Enrico Fermi published the results of his experiments on irradiation of uranium and other chemical elements with neutrons . He had observed nuclear transformations which, in his opinion, led to elements in uranium with a larger atomic number than that of uranium. However, Fermi and his co-workers were unable to provide chemical proof of such a conversion.

Otto Hahn and Lise Meitner , heads of the physics department at KWI, therefore took up this problem at the Kaiser Wilhelm Institute; The execution of the necessary chemical separations and analyzes was entrusted to Straßmann. This marked the beginning of a four-year search for transuranic elements by the Hahn / Meitner / Straßmann working group , which ultimately led to less new knowledge about transuranic elements, but to the discovery of nuclear fission of uranium.

Irène Joliot-Curie and Paul Savitch also referred to the efforts of Hahn, Meitner and Straßmann with regard to transuranium elements when they published their own research in this area in July 1938; The two Paris researchers assumed that a β - emitter they had discovered with a half-life of 3.5 hours “ has an atomic number 93 and that the transuranic elements found by Hahn, Meitner and Straßmann to date are elements 94 to 97 acts. "

Hahn and Straßmann succeeded in chemical proof of the nuclear fission of uranium at the end of 1938 by identifying one of the fission products, namely a radioactive barium isotope that does not occur naturally. The physical interpretation of this process, which was equally puzzling for chemists and nuclear physicists, came a few weeks later by Lise Meitner (who had left Germany in the summer of 1938) and her nephew Otto Frisch . The course of these events, in which Hahn, Meitner and Straßmann were equally involved, is described in detail in the article on the discovery of nuclear fission .

The further work of Straßmann from 1939 to 1946 concerned the elucidation of the fission products of thorium and uranium as well as element 93. Even during the war years, all these research results of the KWI were published in generally accessible journals.

Tailfingen

The KWI in Berlin was badly damaged in air raids in spring 1944 and was therefore relocated to Tailfingen (Württemberg).

At the end of April 1945 Otto Hahn was taken into custody by an American special force in Tailfingen, today a district of Albstadt , and interned together with German scientists from other institutes in Cambridge (England). The physicist Josef Mattauch , who came to the KWI in February 1939 and set up a mass spectrographic department there , therefore took over the temporary management of the institute ; Straßmann was made head of the radiochemical department.

In June 1945 the scientists who remained there received a promise from a French commission under Frédéric Joliot-Curie that they would be able to return to work immediately and without restrictions. At that time, Tailfingen was in the French occupation zone. However, since the laboratories were only provisionally housed in a textile factory and the lack of closer contact with a university was unfavorably noticeable, a move to Tübingen was considered soon afterwards; however, the building complex intended for this purpose was confiscated by the French military authorities after the planning was completed.

Mainz

In May 1946, Joliot-Curie therefore proposed Mainz as the new location. The University of Mainz was supposed to be re-established there, and the neighborhood of the research institute would certainly be upgraded. The first preliminary talks in Mainz with the founding rector of the university were held by Straßmann in June 1946.

Otto Hahn returned from England in early 1946. During his stay there, he had already been elected President of the Kaiser Wilhelm Society ; he therefore no longer took over the management of the Kaiser Wilhelm Institute for Chemistry. His successor and first director at KWI was Josef Mattauch; Fritz Straßmann, the head of the radiochemical department, was appointed second director in 1950. However, since Josef Mattauch lived almost permanently in Switzerland from 1946 to 1951 due to serious illness, Straßmann also had to take on his responsibilities (in Tailfingen and Mainz) during this time and thus manage the new building of the KWI on the university grounds in Mainz. In addition, he had held a chair for inorganic chemistry at the university since July 1946 and had to struggle with great difficulties in setting up the laboratories. Straßmann shuttled back and forth between Tailfingen and Mainz; The French authorities therefore authorized him to buy a car privately at the end of 1947, but his family did not move from Tailfingen to Mainz until the summer of 1949.

The move of the Kaiser Wilhelm Institute, which has since been renamed the Max Planck Institute for Chemistry (MPI for Chemistry), took place in autumn 1949.

Josef Mattauch returned to Mainz in February 1952. He was a physicist and wanted to expand the mass spectrography department. He therefore granted only a very small part of the institute's personnel and material budget to the radiochemical department, so that Straßmann was unable to continue the work of this department in the sense of the tradition of the Dahlem Institute.

Fritz Straßmann left the MPI for Chemistry at his own request on April 1, 1953 and now devoted himself exclusively to teaching and research at the University of Mainz, above all to the establishment and expansion of the inorganic-chemical institute.

Research and teaching at the Johannes Gutenberg University

The then Archbishop of Mainz and Elector Diether von Isenburg opened a university in Mainz in 1477, but after centuries of existence in the turmoil after the French Revolution, it came to a standstill.

After the Second World War, this university in Mainz was revived by the military government of the French occupation zone and opened on May 22, 1946 on the site of a former anti-aircraft barracks under the name "Johannes Gutenberg University". In 1946, however, only the buildings and lecture halls for the two theological faculties and the law and philosophy faculties could be prepared, the other faculties were temporarily housed.

The first post-war years

Fritz Straßmann had been refused a habilitation at the Friedrich-Wilhelms-Universität Berlin during the National Socialist era because of his anti-Nazi attitude. On the occasion of the preliminary discussions at the Johannes Gutenberg University in Mainz in the summer of 1946 because of the relocation of the Kaiser Wilhelm Institute for Chemistry there, the founding rector asked him whether he was ready to come to the university as full professor , and here chemistry To build up “from nothing”.

Straßmann agreed, the rector waived a habilitation process and the appointment was made on July 1, 1946. Straßmann was appointed full professor and head of the Institute of Chemistry, which in this development phase consisted of the departments for inorganic-analytical chemistry, organic chemistry and physical chemistry. The chairs for organic and physical chemistry were not filled until the winter semester 1946/47; the three departments were converted into their own institutes between 1948 and 1951.

Straßmann began teaching inorganic and analytical chemistry in the winter semester 1946/47 in the university auditorium. In 1947 the first laboratory with workplaces for 35 students was put into operation in the chemistry hall of a grammar school in Mainz. The remaining 200 to 300 chemistry students were allowed to carry out the necessary experimental work in schools, factory laboratories or pharmacies under appropriate supervision. Some of the chemicals necessary for the internship were bought by Straßmann personally in the American-occupied zone in Frankfurt; the contents of his backpack were occasionally checked by the military police. Between 1947 and 1948, 60 workplaces were set up in the basement of the university for the inorganic beginner internships.

Institute for Inorganic Chemistry

In the summer of 1949, some of the garages in the former barracks were converted into a small institute for inorganic chemistry, and the first jobs for graduate and doctoral students were now there. In his capacity as head of the radiochemical department of the neighboring MPI for Chemistry, Straßmann was able to provide some of his doctoral students with a job there.

In the 1950/51 winter semester, the Institute for Inorganic Chemistry received an associate professor for Analytical Chemistry, which was filled with Wilhelm Geilmann , one of Straßmann's teachers at the TU Hannover. Geilmann took over the management of the still sparsely equipped analytical laboratories and relieved Straßmann from supervising the beginner's internships and the lectures in analytical chemistry. The job situation for the students improved in 1952/53 after the first new building of the Institute for Inorganic Chemistry was completed; The Marshall Plan helped with the procurement of modern measuring instruments from the USA .

Institute for Inorganic Chemistry and Nuclear Chemistry

After leaving the Max Planck Institute, Straßmann built up his very own research area nuclear chemistry at the university with the aim of continuing the tradition of the Kaiser Wilhelm Institute for Chemistry there. On his initiative and with the support of the board of directors of BASF in Ludwigshafen, the state government of Rhineland-Palatinate granted the university considerable financial resources from the corporation tax revenue of this company to set up the chemical institutes including a modern nuclear chemistry department. In the mid-1950s, the first ever new buildings were built on the university grounds. At the same time, the German Research Foundation provided the funds for a commercial neutron generator , a “pressure tank cascade accelerator”, which was needed as a neutron source for in-depth studies of nuclear fission. The renaming of the Institute for Inorganic Chemistry in "Institute for Inorganic Chemistry and Nuclear Chemistry" (1960) took this into account.

The eventful period of the 1950s was overshadowed by the death of Maria Straßmann in April 1956. In 1959, Straßmann married the journalist Irmgard Hartmann. In April 1957, Straßmann was one of the signatories of the Göttingen Declaration in which eighteen leading German nuclear researchers opposed the government's intention to arm the Bundeswehr with nuclear weapons.

Research reactor

In the middle of this phase, in autumn 1955, the nuclear powers released the know-how of reactor technology at the UN conference “Peaceful Uses of Atomic Energy” in Geneva ; thereafter research reactors were offered commercially. Strassmann held back, however; To him, these systems still seemed too complex and not geared enough to the needs of nuclear chemical work. But he found a reactor that seemed suitable to him in 1958 at the second UN conference in Geneva at the General Atomics company (San Diego / California); it was shown in operation in the accompanying exhibition. A visit to the company in the USA at the end of 1959 confirmed this choice.

The planned type TRIGA Mark II nuclear reactor is a "swimming pool" reactor with around 70 fuel elements, which are arranged at the bottom of a 6 m high water tank. They contain about 2.3 kg of uranium, the content of which in uranium-235 is enriched to 20%. In continuous operation, its maximum output is 100 kW. The special thing about the reactor is that it can also be run in pulse mode. For this purpose, the output of the reactor can be increased to up to 250 MW for a fraction of a second. The pulse operation is used, among other things, to investigate short-lived fission products with half-lives down to the seconds and tenths of a second range. They are isolated within a few seconds from the complex radioactive mixture formed by the short but very intensive neutron irradiation using fully automated separation methods. This "fast chemistry" becomes a trademark of the Mainz nuclear chemistry, which is also reminiscent of the pneumatic tube system installed in the building.

However, more than seven years passed before the Mainz research reactor (FRMZ) was delivered and put into operation , which for Straßmann was filled with lengthy negotiations, building planning, obtaining reports and permits and patiently waiting for a favorable decision.

Institute for Nuclear Chemistry

Institute for Nuclear Chemistry

The inauguration of the reactor took place on April 3, 1967; Straßmann and his colleagues had hoped for an earlier date. However, he was prepared to postpone his upcoming retirement by three years in order to move the reactor and the nuclear chemistry department into an independent institute for nuclear chemistry and to hand over the official duties to his successor. The associated division of the former Straßmann Institute into two independent institutes, the "Institute for Inorganic Chemistry and Analytical Chemistry" and the "Institute for Nuclear Chemistry" did not take place until 1972.

After his retirement (1970), Straßmann kept his apartment on the university campus, which was right next to the reactor. He now had more time to work in the garden and play the violin, and for a few years did his apprenticeship with his students in order to at least get to know the now common methods of nuclear chemistry. However, it was too late for him to do his own research on the reactor.

After a long illness, Fritz Straßmann died on April 22, 1980 in Mainz.

Memorial plaque of the GDCh

The Society of German Chemists has installed the following plaque at the Institute for Nuclear Chemistry in Mainz as part of its " Historic Chemistry Sites " program :

This board reminds of the joint work of
Lise Meitner, Otto Hahn and Fritz Straßmann.

They led to the discovery of nuclear fission by the chemists Otto Hahn (1879–1968) and Fritz Straßmann (1902–1980) on December 17, 1938 in Berlin and its interpretation by the physicists Lise Meitner (1878–1968) and Otto Robert Frisch (1904 –1979) on December 31, 1938 in Kungälv / Sweden.

Unveiled on February 22nd, 2002, the 100th birthday of Fritz Straßmann, who taught and researched at the University of Mainz from 1946 to 1970.

Publications

Only a selection of such publications by Fritz Straßmann is listed here which are not directly related to the search for transuranium elements and the discovery of nuclear fission. Publications on these latter subjects are reported in the article on the discovery of nuclear fission .

The publications by Fritz Straßmann's diploma and doctoral students are not listed here. Contrary to the usual tradition, Straßmann decided not to add his name to these works. Mentioning only the few reports in which this did happen would falsify the overall impression of the research carried out under his suggestion.

  • H. Braune, F. Straßmann: About the solubility of iodine in gaseous carbonic acid . In: Journal of Physical Chemistry . A143, 1929, p. 225-243 .
  • F. Straßmann: Some new uses of the emanation method . In: The natural sciences . No. 19 , 1931, pp. 502-504 .
  • F. Straßmann: Investigations into surface size and lattice changes in crystallized salts according to Hahn's emanation method . In: Journal of Physical Chemistry . B26, 1934, p. 353-361 .
  • F. Straßmann: Investigations into the connection between the lattice structure and gas permeability of organic salts according to Hahn's emanation method . In: Journal of Physical Chemistry . B26, 1934, p. 362-372 .
  • F. Straßmann, E. Walling: The deposition of the pure strontium isotope 87 from an old rubidium-containing lepidolite and the half-life of the rubidium . In: Reports of the German Chemical Society . 71B, 1938, pp. 1-9 .
  • F. Straßmann, M. Straßmann-Heckter: Barium . In: Handbook of Analytical Chemistry. Third part: Quantitative methods of determination and separation . Volume IIa: Elements of the second main group. Springer-Verlag, Berlin 1940, p. 365-402 .
  • F. Straßmann: The filling and expansion of the periodic system . In: The natural sciences . No. 29 , 1941, pp. 492-496 .
  • O. Hahn, F. Straßmann, J. Mattauch, H. Ewald: Geological age determination by the strontium method . In: Researches and Advances . No. 18 , 1942, p. 353-355 .
  • S. Knoke, F. Straßmann: Hermann Braune for his 60th birthday. In: Journal of Nature Research A . 2, 1947, pp. 183-184 ( online ).
  • F. Straßmann: Peaceful chemistry of atomic nuclei . In: Mainz University Speeches . No. 14 . Kupferberg, Mainz 1949.
  • F. Straßmann: For research into radioactivity. Lise Meitner on her 75th birthday . In: Angewandte Chemie . No. 66 , 1954, pp. 93-95 .
  • F. Straßmann: Otto Hahn on his 80th birthday . In: Messages from the Max Planck Society . No. 1 , 1959, p. 18-19 .
  • HJ Born, F. Straßmann: Otto Hahn (1879-1968) . In: Radiochimica Acta . No. 9/2 , 1968, p. 2 .
  • A. Klemm, F. Straßmann: Otto Hahn in memory. In: Journal of Nature Research A . 24, 1969, pp. 485-494 ( online ).
  • F. Straßmann: How atomic fission was discovered . In: Yearbook of the Association of Friends of the University of Mainz . 1969, p. 50-54 .
  • F. Straßmann, G. Herrmann: The Institute for Nuclear Chemistry and the Reactor . In: Fritz Krafft (Ed.): Mathematics and natural sciences at the Johannes Gutenberg University . Steiner, Wiesbaden 1977, p. 51-55 .

Since the sixties he was co-editor of the papers for German and international politics .

Honors

literature

  • Fritz Krafft : In the shadow of sensation. Life and work of Fritz Straßmann. Verlag Chemie, Weinheim, 1981. ISBN 3-527-25818-3
  • Peter Brommer, Günter Herrmann: Fritz Straßmann (1902–1980). Co-discoverer of nuclear fission. Inventory of the estate and comments on the attempts at nuclear fission. Verlag der Landesarchivverwaltung Rheinland-Pfalz, Koblenz, Volume 95, 2001. ISBN 3-931014-57-6
  • Günter Herrmann: Fritz Straßmann - co-discoverer of nuclear fission. In: Quarterly issues for culture, politics, economics and history . 16th year, No. 1, 1996, pages 29–33 (with 3 photos by Fritz Straßmann)
  • Brochure of the GDCh : Historic sites of science. Lise Meitner, Otto Hahn and Fritz Straßmann. Mainz, February 22nd, 2002 (with 4 photos by Fritz Straßmann)
  • Fritz Krafft: Fritz Straßmann and the development of Mainz chemistry. In: Michael Kißener , Friedrich Moll (ed.): Ut omnes unum sint (part 3). Founding professors in chemistry and pharmacy . (Contributions to the history of the University of Mainz, NF 7, pages 13–68). Stuttgart: Franz Steiner 2009. ISBN 978-3-515-09302-6 .

Individual evidence

  1. ↑ E. Fermi: "Radioactivity Induced by Neutron Bombardment", in: Nature 1934 , 133 , 757-757; doi: 10.1038 / 133757a0 .
  2. ↑ E. Fermi: "Element No. 93", in: Nature 1934 , 133 , 863-864; doi: 10.1038 / 133863e0 .
  3. ^ E. Fermi: "Possible Production of Elements of Atomic Number Higher than 92", in: Nature 1934 , 133 , 898-899; doi: 10.1038 / 133898a0 .
  4. ^ I. Curie, P. Savitch: Sur les radioéléments formés dans l'uranium irradié par les neutrons II . Le Journal de Physique et le Radium 9 (1938) pp. 355-359.
  5. ↑ Text of the Göttingen Declaration 1957 at uni-goettingen.de
  6. ↑ JPL Small-Body Database Browser: Asteroid Strassmann .

Web links

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personal data
SURNAME Straßmann, Fritz
ALTERNATIVE NAMES Straßmann, Friedrich Wilhelm (full name)
BRIEF DESCRIPTION German chemist
DATE OF BIRTH February 22, 1902
PLACE OF BIRTH Boppard
DATE OF DEATH April 22, 1980
Place of death Mainz