- Category : Chemist
- Type : MGE
- Profile : 2/4 - Hermit / Opportunist
- Definition : Triple Split
- Incarnation Cross : RAX Rulership 1
Otto Hahn, OBE, ForMemRS (8 March 1879 – 28 July 1968) was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry".
Hahn was a courageous opposer of Jewish persecution by the Nazi Party and after World War II he became a passionate campaigner against the use of nuclear energy as a weapon. He served as the last President of the Kaiser Wilhelm Society (KWG) in 1946 and as the founding President of the Max Planck Society (MPG) from 1948 to 1960. Considered by many to be a model for scholarly excellence and personal integrity, he became one of the most influential and revered citizens of the Federal Republic of Germany.
Hahn was the youngest son of Heinrich Hahn (1845–1922), a prosperous glazier and entrepreneur ("Glasbau Hahn"), and Charlotte Hahn, née Giese (1845–1905). Together with his brothers Karl, Heiner and Julius, Otto was raised in a sheltered environment. At the age of 15, he began to take a special interest in chemistry and carried out simple experiments in the laundry room of the family home. His father wanted Otto to study architecture, as he had built or acquired several residential and business properties. But Otto persuaded him that his ambition was to become an industrial chemist.
In 1897, after taking his Abitur at the Klinger Oberrealschule in Frankfurt, Hahn began to study chemistry and mineralogy at the University of Marburg. His subsidiary subjects were physics and philosophy. Hahn joined the Students' Association of Natural Sciences and Medicine, a student fraternity and a forerunner of today's Nibelungia Fraternity. He spent his third and fourth semester studying under Adolf von Baeyer at the University of Munich. In 1901, Hahn received his doctorate in Marburg for a dissertation entitled On Bromine Derivates of Isoeugenol, a topic in classical organic chemistry. After completing his one year military service, the young chemist returned to the University of Marburg, where for two years he worked as assistant to his doctoral supervisor, Geheimrat Professor Theodor Zincke.
Hahn's intention had been to work in industry. With this in mind, and also to improve his knowledge of English, he took up a post at University College London in 1904, working under Sir William Ramsay, known for having discovered the inert gases. Here Hahn worked on radiochemistry, at that time a very new field. In 1905, in the course of his work with salts of radium, Hahn discovered a substance he called radiothorium (thorium-228), which at that time was believed to be a new radioactive element. (In fact, it was a still undiscovered isotope of the known element thorium. The term isotope was only coined in 1913, by the British chemist Frederick Soddy). From September 1905 until summer 1906, Hahn visited Montreal, Canada, where he worked under Ernest Rutherford in the McDonalds-Physics-Building at McGill University and discovered thorium C (later identified as polonium-212) and radioactinium (later identified as thorium-227) and investigated the alpha-rays of radiothorium.
In summer 1906, Hahn returned to Germany, where he collaborated with Emil Fischer at the University of Berlin. Fischer placed at his disposal a former woodworking shop ("Holzwerkstatt") in the Chemical Institute to use as his own laboratory. There, in the space of a few months, using extremely primitive apparatus, Hahn discovered mesothorium I, mesothorium II and - independently from Bertram Boltwood - the mother substance of radium, ionium. In subsequent years, mesothorium I (radium-228) assumed great importance because, like radium-226 (discovered by Pierre and Marie Curie), it was ideally suited for use in medical radiation treatment, while costing only half as much to manufacture. (In 1914, for the discovery of mesothorium I, Otto Hahn was first nominated for the Nobel Prize in Chemistry by Adolf von Baeyer). In June 1907, by means of the traditional habilitation thesis, Hahn qualified to teach at the University of Berlin. On 28 September 1907 he made the acquaintance of the young Austrian physicist Lise Meitner, who had transferred from Vienna to Berlin. So began the thirty-year collaboration and lifelong close friendship between the two scientists.
After the physicist Harriet Brooks had observed a radioactive recoil in 1904, but interpreted it wrongly, Otto Hahn succeeded, in the winter of 1908/09, in demonstrating the radioactive recoil incident to alpha particle emission and interpreting it correctly.
"...a profoundly significant discovery in physics with far-reaching consequences",
as the physicist Walther Gerlach put it.
1909 Hahn und Meitner, using the new socalled 'recoil-method', were able to discover and isolate the isotopes tallium- 207, tallium-208, tallium-210 and polonium-214.
In 1910 Hahn was appointed professor, and in 1912 he became head of the Radioactivity Department of the newly founded Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem (since 1956 "Otto Hahn Building of the Free University", Berlin, Thielallee 63). Succeeding Alfred Stock, Hahn was director of the institute from 1928 to 1946. As early as 1924, Hahn was elected to full membership of the Prussian Academy of Sciences in Berlin (proposed by Albert Einstein, Max Planck, Fritz Haber, Wilhelm Schlenk and Max von Laue).
In June 1911, while attending a conference in Stettin (today Szczecin, Poland) Otto Hahn met Edith Junghans (1887–1968), an art student. On 22 March 1913 the couple married in Edith's native city of Stettin, where her father, Paul Ferdinand Junghans, was a high-ranking law officer and President of the City Parliament until his 1915 death. Their only child, Hanno, born in 1922, became a distinguished art historian and architectural researcher (at the Hertziana in Rome). In 1960, while on a study trip in France, Dr Hanno Hahn was involved in a fatal car accident, together with his wife and assistant Ilse Hahn, née Pletz. They left a fourteen-year-old son, Dietrich. In 1990, the Hanno and Ilse Hahn Prize for outstanding contributions to Italian art history was established in memory of Hanno and Ilse Hahn to support young and talented art historians. It is awarded biennally by the Bibliotheca Hertziana - Max Planck Institute of Art History in Rome.
During the First World War, Hahn was conscripted into the army, where he was assigned, together with James Franck and Gustav Hertz, to the special unit for chemical warfare under the direction of Fritz Haber. The unit developed, tested and produced poison gas for military purposes, and was sent to both the western and eastern front lines. In December 1916, Hahn was transferred to the "Headquarters of His Majesty" in Berlin, and was able to resume his radiochemical research in his institute. In 1917/18 Hahn and Lise Meitner isolated a long-lived activity, which they named "proto-actinium". Already in 1913, Kazimierz Fajans and Göhring had isolated a short-lived activity from uranium X2 (later known as 234mPa) and called the substance "brevium". The two activities were different isotopes of the same undiscovered element no. 91. Finally in 1949, the International Union of Pure and Applied Chemistry (IUPAC) named this new element protactinium and confirmed Hahn and Meitner as discoverers.
In February 1921, Otto Hahn published the first report on his discovery of uranium Z (later known as 234Pa ), the first example of nuclear isomerism.
"...a discovery that was not understood at the time but later became highly significant for nuclear physics",
as Walther Gerlach remarked. And, indeed, it was not until 1936 that the young physicist Carl Friedrich von Weizsäcker succeeded in providing a theoretical explanation of the phenomenon of nuclear isomerism. For this discovery, whose full significance was recognized by very few, Hahn was again proposed, in 1923, for the Nobel Prize in Chemistry, this time by Max Planck, among others.
In the early 1920s, Otto Hahn created a new field of work. Using the "emanation method", which he had recently developed, and the "emanation ability", he founded what became known as "Applied Radiochemistry" for the researching of general chemical and physical-chemical questions. In 1933 he published a book in English (and later in Russian) entitled "Applied Radiochemistry", which contains the lectures given by Hahn when he was a visiting professor at Cornell University in Ithaca, New York in 1933.
In 1966, Glenn T. Seaborg, co-discoverer of many transuranium elements and President of the United States Atomic Energy Commission, wrote about this book as follows:
"As a young graduate student at the University of California at Berkeley in the mid-1930s and in connection with our work with plutonium a few years later, I used his book "Applied Radiochemistry" as my bible. This book was based on a series of lectures which Professor Hahn had given at Cornell in 1933; it set forth the "laws" for the co-precipitation of minute quantities of radioactive materials when insoluble substances were precipitated from aqueous solutions. I recall reading and rereading every word in these laws of co-precipitation many times, attempting to derive every possible bit of guidance for our work, and perhaps in my zealousness reading into them more than the master himself had intended. I doubt that I have read sections in any other book more carefully or more frequently than those in Hahn's "Applied Radiochemistry". In fact, I read the entire volume repeatedly and I recall that my chief disappointment with it was its length. It was too short."
And Glenn Seaborg added:
"I believe that it is fair to refer to Otto Hahn as the father of radiochemistry and of its more recent offspring nuclear chemistry. For his special genius the world of science will be forever grateful."
The discovery of Nuclear Fission
Jointly with Lise Meitner and his pupil and assistant Fritz Straßmann (1902–1980), Otto Hahn furthered the research begun by Enrico Fermi and his team in 1934 when they bombarded uranium with neutrons. Until 1938, it was believed that the elements with atomic numbers greater than 92 (known as transuranium elements) arise when uranium atoms are bombarded with neutrons. The German chemist Ida Noddack proposed an exception. She anticipated the paradigm shift of 1938/39 in her article published in the journal Angewandte Chemie, Nr. 47, 1934, in which she speculated:
"It is conceivable that when heavy nuclei are bombarded with neutrons these nuclei could break down into several fairly large fragments, which are certainly isotopes of known elements, but not neighbours of the irradiated elements."
But no physicist or chemist really took Noddack's speculation seriously or tested it, not even Ida Noddack herself. The idea that heavy atomic nuclei could break down into lighter elements was regarded as totally inadmissible.
Between 1934 and 1938, Hahn, Meitner, and Strassmann found a great number of radioactive transmutation products, all of which they regarded as transuranic. At that time the existence of actinides was not yet established, and uranium was wrongly believed to be a group 6 element similar to tungsten. It followed that first transuranic elements would be similar to group 7 to 10 elements, i.e. rhenium and platinoids. The Hahn group was indeed able to establish the presence of multiple isotopes of at least four such elements and (mistakenly) identify them as elements with atomic numbers 93 through 96. They were the first scientists to measure the half-life of 239U and to establish chemically that it was an isotope of uranium, but they were unable to continue this work to its logical conclusion and to identify the decay product of 239U - namely, neptunium (the real element 93); this task was only completed by Edwin McMillan and Philip H. Abelson in 1940.
On 13 July 1938, with the help and support of Hahn, Lise Meitner emigrated to Stockholm, while Hahn continued to work with Strassmann. In late 1938 they found evidence of isotopes of an alkaline earth metal in their sample. The metal was detected by the use of an organic barium salt constructed by Wilhelm Traube. Finding a group 2 alkaline earth metal was problematic, because it did not logically fit with the other elements found thus far. Hahn initially suspected it to be radium, produced by splitting off two alpha-particles from the uranium nucleus. At the time, the scientific consensus was that even splitting off two alpha particles via this process was unlikely. The idea of turning uranium into barium (by removing around 100 nucleons) was seen as preposterous. On 10 November during a visit to Copenhagen, Hahn discussed these results with Niels Bohr and Lise Meitner. Further refinements of the technique, leading to the decisive experiment on 16–17 December 1938 (the celebrated "radium-barium-mesothorium-fractionation"), produced puzzling results: the three isotopes consistently behaved not as radium, but as barium. Hahn described the results in a letter to Meitner on 19 December: "...we are more and more coming to the awful conclusion that our Ra isotopes behave not like Ra, but like Ba. ... Perhaps you can suggest some fantastic explanation. We ourselves realize that it can't really burst into Ba." In her reply, Meitner concurred that Hahn's conclusion of 'the bursting of the uranium nucleus' was very difficult to accept, but considered it possible.
On 22 December 1938, Hahn sent a manuscript to Naturwissenschaften reporting their radiochemical results. On 27 December, Hahn telephoned the editor of Naturwissenschaften and requested to add a paragraph to the article, speculating that some platinum group elements previously observed in irradiated uranium, which were originally interpreted as transuranium elements, could in fact be technetium (then called "Masurium") and lower platinum group metals (atomic numbers 43 through 46). By January 1939 he was sufficiently convinced that formation of light elements was occurring in his setup that he published a new revision of the article, essentially retracting former claims of observing transuranic elements and neighbors of uranium, and concluding instead that he was seeing light platinoids, barium, lanthanum, and cerium.
As a chemist, Hahn was reluctant to propose a revolutionary discovery in physics. However, Lise Meitner and her nephew, the young physicist Otto Robert Frisch, in Sweden, came to the same conclusion and were able to work out the basic mathematics of nuclear fission - the term that was coined by Frisch, and which subsequently became internationally known. Over the next few months, Meitner and Frisch published two articles discussing and experimentally confirming this hypothesis.
In a later appreciation (1963), Lise Meitner wrote:
"The discovery of nuclear fission by Otto Hahn and Fritz Strassmann opened up a new era in human history. It seems to me that what makes the science behind this discovery so remarkable is that it was achieved by purely chemical means."
And in an interview on West German television (ARD, 8 March 1959), Meitner said:
"Hahn and Strassmann were able to do this by exceptionally good chemistry, fantastically good chemistry, which was way ahead of what anyone else was capable of at that time. The Americans learned to do it later. But at that time, Hahn and Strassmann were really the only ones who could do it. And that was because they were such good chemists. Somehow they really succeeded in using chemistry to demonstrate and prove a physical process."
Fritz Strassmann responded with this clarification:
"Professor Meitner stated that the success could be attributed to chemistry. I have to make a slight correction. Chemistry merely isolated the individual substances, it did not precisely identify them. It took Professor Hahn's method to do this. This is where his achievement lies."
In their second publication on nuclear fission (Die Naturwissenschaften, 10 February 1939) Otto Hahn and Fritz Strassmann used for the first time the name Uranspaltung (uranium fission) and predicted the existence and liberation of additional neutrons during the fission process, which was proved to be a chain reaction by Frédéric Joliot and his team in March 1939.
During the war, Otto Hahn - together with his assistants Hans-Joachim Born, Siegfried Flügge, Hans Götte, Walter Seelmann-Eggebert and Fritz Strassmann - worked on uranium fission reactions. By 1945 he had drawn up a list of 25 elements and about 100 isotopes whose existence he had demonstrated.
At the end of World War II in 1945 Hahn was suspected of working on the German nuclear energy project to develop an atomic reactor or an atomic bomb. But his only connection was the discovery of fission; he did not work on the program. - In April 1945, Hahn and nine leading German physicists (including Max von Laue, Werner Heisenberg and Carl Friedrich von Weizsäcker) were taken into custody by the Alsos Mission and interned at Farm Hall, Godmanchester, near Cambridge, England from 3 July 1945 to 3 January 1946. While they were there, the German scientists learned of the dropping of the American atom bombs on Hiroshima and Nagasaki on 6 August and 9 August 1945. Hahn was on the brink of despair, as he felt that because he had discovered nuclear fission he shared responsibility for the death and suffering of tens of thousands of innocent Japanese people. Early in January 1946, the group was allowed to return to Germany.
The Nobel Prize in Chemistry
On 15 November 1945 the Royal Swedish Academy of Sciences announced that Hahn had been awarded the 1944 Nobel Prize in Chemistry "for his discovery of the fission of heavy atomic nuclei." Some historians have documented the history of the discovery of nuclear fission and believe Meitner should have been awarded the Nobel Prize with Hahn. Hahn was still being detained at Farm Hall when the announcement was made; thus, his whereabouts were a secret and it was impossible for the Nobel committee to send him a congratulatory telegram. Instead, he learned about his award through the Daily Telegraph newspaper. His fellow interned German scientists celebrated his award on 18 November by giving speeches, making jokes, and composing songs. On 4 December, Hahn was persuaded by two of his captors to write a letter to the Nobel committee accepting the prize but also stating that he would not be able to attend the award ceremony. He could not participate in the Nobel festivities on 10 December since his captors would not allow him to leave Farm Hall.
"Surely Hahn fully deserved the Nobel Prize in chemistry. There is really no doubt about it. But I believe that Otto Robert Frisch and I contributed something not insignificant to the clarification of the process of uranium fission - how it originates and that it produces so much energy, and that was something very remote from Hahn. For this reason I find it a bit unjust that in newspapers I was called a Mitarbeiterin [co-worker] of Hahn's in the same sense that Strassman was."
wrote Lise Meitner to her friend Eva von Bahr-Bergius in November 1945. And Meitner's former assistant Carl Friedrich von Weizsäcker later added:
"He certainly did deserve this Nobel Prize. He would have deserved it even if he had not made this discovery. But everyone recognized that the splitting of the atomic nucleus merited a Nobel Prize."
Hahn attended the Nobel festivities the year after he was awarded the prize. On 10 December 1946, King Gustav V of Sweden finally presented him with his Nobel Prize medal and diploma.
Max Planck Society
From 1948 to 1960 Otto Hahn was the founding President of the newly formed Max Planck Society for the Advancement of Science, which through his tireless activity and his worldwide respected personality succeeded in regaining the renown once enjoyed by the Kaiser Wilhelm Society. Immediately after the Second World War, Hahn reacted to the dropping of the atomic bombs on Hiroshima and Nagasaki by coming out strongly against the use of nuclear energy for military purposes. He saw the application of his scientific discoveries to such ends as a misuse, or even a crime. Consequently, among other things, he initiated the Mainau Declaration of 1955, in which a large number of Nobel Prize-winners called attention to the dangers of atomic weapons and warned the nations of the world urgently against the use of "force as a final resort". He was also instrumental and one of the authors of the Göttingen Manifesto of 1957, in which, together with 17 leading German atomic scientists, he protested against a proposed nuclear arming of the new West German armed forces (Bundeswehr). In January 1958, Otto Hahn, together with his friend Albert Schweitzer signed the Pauling Appeal to the United Nations for the "immediate conclusion of an international agreement to stop the testing of nuclear weapons", and in October he signed the international Agreement to call a meeting to draw up a world constitution. Right up to his death, he never tired of warning urgently of the dangers of the nuclear arms race between the great powers and of the radioactive contamination of the planet.
From 1957, Hahn was repeatedly nominated for the Nobel Peace Prize by a number of international organizations, including the largest French trade union, the Confederation Generale du Travail (CGT). Linus Pauling, the 1962 Nobel Peace laureate, once described Otto Hahn as "an inspiration to me."
Honours and awards
During World War I, Hahn was awarded the Iron Cross, 1st and 2nd class, both in 1915, and a knight of the House Order of Hohenzollern (1917) and the Albert Order of Saxony (1917).
Otto Hahn received many governmental honours and academic awards from all over the world for his scientific work. He was elected member or honorary member of 45 Academies and scientific societies (among them the University of Cambridge, the Physical Society, the University College and the Royal Society in London (1957) and the Academies in Allahabad (India), Bangalore (India), Berlin, Boston (USA), Bucharest, Copenhagen, Göttingen, Halle, Helsinki, Lisbon, Madrid, Munich, Rome, Stockholm, Vatican, Vienna) and received 37 of the highest national and international orders and medals, among them the Gold Medals Emil Fischer, Cannizzaro, Copernicus, Henri Becquerel, Paracelsus and Hugo Grotius, the Max Planck medal, the Faraday Lectureship Prize with Medal from the Royal Society of Chemistry in London and the Harnack medal in Gold from the Max Planck Society. In 1956 he received the Gold Cross of Greek Order of the Redeemer, in 1957 he was awarded the Order of the British Empire and in 1959 President Charles de Gaulle of France appointed him an Officer of the Légion d'Honneur. Hahn was made a knight of the Peace Class of the Order Pour le Mérite in 1952, and received the Grand Merit Cross with Star and Sash of the Order of Merit of the Federal Republic of Germany (1954), which was subsequently upgraded in 1959 to Grand Cross 1st class. In 1961 Pope John XXIII awarded him the Gold Medal of the Pontifical Academy of Sciences in the Vatican.
In 1957 Hahn was elected an honorary citizen of the city of Magdeburg, DDR (German Democratic Republic), and in 1958 an honorary member of the Academy of Sciences of the USSR (today Russian Academy of Sciences) in Moscow, but he declined both honours.
In 1966, President Lyndon B. Johnson of the USA, and the United States Atomic Energy Commission (AEC) in Washington awarded Hahn (together with Lise Meitner and Fritz Strassmann) the Enrico Fermi Prize. This was the only time the Fermi Prize has been awarded to non-Americans.
Hahn was made an honorary citizen of the cities of Frankfurt am Main and Göttingen, and of the land and the city of Berlin. The day after his death, the Max Planck Society published the following obituary notice in all the major newspapers:
"On 28 July, in his 90th year, our Honorary President Otto Hahn passed away. His name will be recorded in the history of humanity as the founder of the atomic age. In him Germany and the world have lost a scholar who was distinguished in equal measure by his integrity and personal humility. The Max Planck Society mourns its founder, who continued the tasks and traditions of the Kaiser Wilhelm Society after the war, and mourns also a good and much loved human being, who will live in the memories of all who had the chance to meet him. His work will continue. We remember him with deep gratitude and admiration."
Proposals were made at different times, first in 1971 by American chemists, that the newly syntheticized element no. 105 should be named Hahnium in Hahn's honour, although in 1997 the IUPAC (International Union of Pure and Applied Chemistry) finally named it Dubnium, after the Russian research center in Dubna (see element naming controversy). Although element 108 was given the name Hassium by its officially-recognised German discoverers in 1992, a 1994 IUPAC committee recommended that it be named Hahnium (Hn), in spite of the long-standing convention to give the discoverer the right to suggest a name. This recommendation was not adopted, following protests from the German discoverers, and the name Hassium (Hs) was adopted internationally in 1997.
In 1964 the only European nuclear-powered civilian ships, the freighter NS Otto Hahn, was named in his honour. In 1959 there were the opening ceremonies of the Otto Hahn Institute in Mainz and the Hahn-Meitner-Institut for Nuclear Research (HMI) in Berlin. There are craters on Mars and the Moon, and the asteroids No. 2962 Otto, No. 3676 Hahn and No. 19126 Ottohahn named in his honour, as were the Otto Hahn Prize of both the German Chemical and Physical Societies, the Otto Hahn Medal of the Max Planck Society and the Otto Hahn Peace Medal of the United Nations Association of Germany in Berlin.
Many cities and districts in the German speaking countries have named secondary schools after him, and streets, squares and bridges throughout Europe bear his name. More than twenty states worldwide have honoured Otto Hahn by issuing coins, medals or stamps with his portrait. An island in the Antarctic (near Mt. Discovery) was also named after him, as were two Intercity trains of the German Federal Railways in 1971, running between Hamburg and Basel SBB, and the Otto Hahn Library in Göttingen. In 1974, in appreciation of the special contribution of Otto Hahn to German-Israeli relations, a wing of the Weizmann Institute of Science in Rehovot, Israel, was given his name, and a scientific research center of the Saint Louis University (Baguio) (Philippines) was named the Otto Hahn Building. In several cities and districts Otto Hahn busts, monuments and memorial plaques were unveiled, including in Vienna in the foyer of the International Atomic Energy Agency. There are public Otto Hahn Centers in Göttingen and Ottobrunn (near Munich), and planned in the next future also in Hahn's native city Frankfurt/Main, while in 2011 the city of Albstadt opened an Otto Hahn memorial place in the local IHK-Academy. A special honour in 1997 was conferred on Hahn in the Netherlands: after a cactus (Trichocereus echinopsis Otto Hahn) and an azalea already bore his name (Rhododendron luteum var Otto Hahn), Dutch rose growers named a new variety of rose rosa ottohahniana.
At the end of 1999 the German newsmagazine FOCUS published an inquiry of 500 leading natural scientists, engineers and physicians about the most important scientists of the 20th century. In this poll the experimental chemist Otto Hahn - after the theoretical physicists Albert Einstein and Max Planck - was elected third (with 81 points) and thus the most significant empiric researcher of his time.