After the war he became the head of the Kaiser Wilhelm Institute for Chemistry, while remaining in charge of his own department. Between 1934 and 1938, he worked with Strassmann and Meitner on the study of isotopes created through the neutron bombardment of uranium and thorium, which led to the discovery of nuclear fission. He was an opponent of national socialism and the persecution of Jews by the Nazi Party that caused the removal of many of his colleagues, including Meitner, who was forced to flee Germany in 1938. During World War II, he worked on the German nuclear weapons program, cataloguing the fission products of uranium.
Introduction
Otto Hahn
Otto Hahn | Introduction
Radioactive isotopes of radium, thorium, protactinium and uranium, Phenomena of Radioactive recoil & Nuclear Isomerism among many others. Hahn and Lise Meitner discovered radioactive isotopes of radium, thorium, protactinium and uranium. He also discovered the phenomena of radioactive recoil and nuclear isomerism, and pioneered rubidium–strontium dating. Hahn and Lise Meitner discovered radioactive isotopes of radium, thorium, protactinium and uranium. He also discovered the phenomena of radioactive recoil and nuclear isomerism, and pioneered rubidium–strontium dating. Several, including radiothorium (thorium-228)
where do the nuclear and weak interaction forces occur
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In the Nuclear Fission
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what is this process about?
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The weak interaction, also known as the weak force or weak nuclear force, is the mechanism of interaction between subatomic particles responsible for the radioactive decay of atoms.
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what is meant by the process where it occur?
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Nuclear fission is a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei.
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who discovered it?
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German Otto Hahn and his assistant Fritz Strassmann
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where is the former from?
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He was from Frankfurt am Main
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what else has he discovered?
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In 1906, Hahn returned to Germany, where Fischer placed at his disposal a former woodworking shop ("Holzwerkstatt") in the basement of the Chemical Institute to use as a laboratory. Hahn equipped it with electroscopes to measure alpha and beta particles and gamma rays. In Montreal these had been made from discarded coffee tins; Hahn made the ones in Berlin from brass, with aluminium strips insulated with amber. These were charged with hard rubber sticks that he rubbed then against the sleeves of his suit. It was not possible to conduct research in the wood shop, but Alfred Stock, the head of the inorganic chemistry department, let Hahn use a space in one of his two private laboratories.
Otto Hahn | Discovery of mesothorium I
Rutherford remarked that: "Hahn has a special nose for discovering new elements."
Otto Hahn | Discovery of radio thorium, and other "new elements"
Along the way, Hahn determined that just as he was unable to separate thorium from radiothorium, so he could not separate mesothorium from radium. Hahn completed his habilitation in the spring of 1907, and became a "Privatdozent". A thesis was not required; the Chemical Institute accepted one of his publications on radioactivity instead. Most of the organic chemists at the Chemical Institute did not regard Hahn's work as real chemistry. Fischer objected to Hahn's contention in his habilitation colloquium that many radioactive substances existed in such tiny amounts that they could only be detected by their radioactivity, venturing that he had always been able to detect substances with his keen sense of smell, but soon gave in.
Otto Hahn | Discovery of mesothorium I
Hahn was thinking only of actinium, but on reading his paper, Meitner told him that he had found a new way of detecting radioactive substances. They set up some tests, and soon found actinium C (thallium-207) and thorium C (thallium-208). The physicist Walther Gerlach described radioactive recoil as "a profoundly significant discovery in physics with far-reaching consequences". In 1910, Hahn was appointed professor by the Prussian Minister of Culture and Education, August von Trott zu Solz. Two years later, Hahn became head of the Radioactivity Department of the newly founded Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem (in what is today the Hahn-Meitner-Building of the Free University of Berlin).
Otto Hahn | Discovery of radioactive recoil
As a consequence, at the end of the war he was arrested by the Allied forces, and was incarcerated in Farm Hall with nine other German scientists, from July 1945 to January 1946.
Otto Hahn | Introduction
It was the first of over 250 scientific publications of Otto Hahn in the field of radiochemistry. At the end of his time in London, Ramsay asked Hahn about his plans for the future, and Hahn told him about the job offer from Kalle & Co. Ramsay told him radiochemistry had a bright future, and that someone who had discovered a new radioactive element should go to the University of Berlin. Ramsay wrote to Emil Fischer, the head of the chemistry institute there, who replied that Hahn could work in his laboratory, but could not be a "Privatdozent" because radiochemistry was not taught there.
Otto Hahn | Discovery of radio thorium, and other "new elements"
Otto Hahn (8 March 1879 – 28 July 1968) was a German chemist, and a pioneer in the fields of radioactivity and radiochemistry. Hahn is referred to as the father of nuclear chemistry. Hahn and Lise Meitner discovered radioactive isotopes of radium, thorium, protactinium and uranium. He also discovered the phenomena of radioactive recoil and nuclear isomerism, and pioneered rubidium–strontium dating. In 1938, Hahn, Lise Meitner and Fritz Strassmann discovered nuclear fission, for which Hahn received the 1944 Nobel Prize for Chemistry. Nuclear fission was the basis for nuclear reactors and nuclear weapons. A graduate of the University of Marburg, Hahn studied under Sir William Ramsay at University College London, and at McGill University in Montreal under Ernest Rutherford, where he discovered several new radioactive isotopes.
Otto Hahn | Introduction
One department head remarked: "it is incredible what one gets to be a "Privatdozent" these days!" Physicists were more accepting of Hahn's work, and he began attending a colloquium at the Physics Institute conducted by Heinrich Rubens. It was at one of these colloquia where, on 28 September 1907, he made the acquaintance of the Austrian physicist Lise Meitner. Almost the same age as himself, she was only the second woman to receive a doctorate from the University of Vienna, and had already published two papers on radioactivity. Rubens suggested her as a possible collaborator. So began the thirty-year collaboration and lifelong close friendship between the two scientists.
Otto Hahn | Discovery of mesothorium I
After the war he became the head of the Kaiser Wilhelm Institute for Chemistry, while remaining in charge of his own department. Between 1934 and 1938, he worked with Strassmann and Meitner on the study of isotopes created through the neutron bombardment of uranium and thorium, which led to the discovery of nuclear fission. He was an opponent of national socialism and the persecution of Jews by the Nazi Party that caused the removal of many of his colleagues, including Meitner, who was forced to flee Germany in 1938. During World War II, he worked on the German nuclear weapons program, cataloguing the fission products of uranium.
Otto Hahn | Introduction
Hahn's intention was still to work in industry. He received an offer of employment from Eugen Fischer, the director of (and the father of organic chemist Hans Fischer), but a condition of employment was that Hahn had to have lived in another country and have a reasonable command of another language. With this in mind, and to improve his knowledge of English, Hahn took up a post at University College London in 1904, working under Sir William Ramsay, who was known for having discovered the inert gases. Here Hahn worked on radiochemistry, at that time a very new field. In early 1905, in the course of his work with salts of radium, Hahn discovered a new substance he called radiothorium (thorium-228), which at that time was believed to be a new radioactive element.
Otto Hahn | Discovery of radio thorium, and other "new elements"
This came with an annual salary of 5,000 marks. In addition, he received 66,000 marks in 1914 (of which he gave 10 per cent to Meitner) from Knöfler for the mesothorium process. The new institute was inaugurated on 23 October 1912 in a ceremony presided over by Kaiser Wilhelm II. The Kaiser was shown glowing radioactive substances in a dark room. The move to new accommodation was fortuitous, as the wood shop had become thoroughly contaminated by radioactive liquids that had been spilt, and radioactive gases that had vented and then decayed and settled as radioactive dust, making sensitive measurements impossible.
Otto Hahn | Discovery of radioactive recoil
(In fact, it was an isotope of the known element thorium; the concept of an isotope, along with the term, was only coined in 1913, by the British chemist Frederick Soddy). Ramsay was enthusiastic when yet another new element was found in his institute, and he intended to announce the discovery in a correspondingly suitable way. In accordance with tradition this was done before the committee of the venerable Royal Society. At the session of the Royal Society on 16 March 1905 Ramsay communicated Hahn's discovery of radiothorium. The "Daily Telegraph" informed its readers: Hahn published his results in the "Proceedings of the Royal Society" on 24 March 1905.
Otto Hahn | Discovery of radio thorium, and other "new elements"
He returned to Germany in 1906, and Emil Fischer placed a former woodworking shop in the basement of the Chemical Institute at the University of Berlin at his disposal to use as a laboratory. Hahn completed his habilitation in the spring of 1907, and became a "Privatdozent". In 1912, he became head of the Radioactivity Department of the newly founded Kaiser Wilhelm Institute for Chemistry. Working with the Austrian physicist Lise Meitner in the building that now bears their names, he made a series of groundbreaking discoveries, culminating with her isolation of the longest-lived isotope of protactinium in 1918. During World War I he served with a "Landwehr" regiment on the Western Front, and with the chemical warfare unit headed by Fritz Haber on the Western, Eastern and Italian fronts, earning the Iron Cross (2nd Class) for his part in the First Battle of Ypres.
Otto Hahn | Introduction
In December 1938, German chemist Otto Hahn and his assistant Fritz Strassmann sent a manuscript to the German science journal "Naturwissenschaften" ("Natural Sciences") reporting that they had detected and identified the element barium after bombarding uranium with neutrons. Their article was published on 6 January 1939. On 19 December 1938, eighteen days before the publication, Otto Hahn communicated these results and his conclusion of a "bursting" of the uranium nucleus in a letter to his colleague and friend Lise Meitner, who had fled Germany in July to the Netherlands and then to Sweden. Meitner and her nephew Otto Robert Frisch confirmed Hahn's conclusion of a "bursting" and correctly interpreted the results as "nuclear fission" – a term coined by Frisch.
German nuclear weapons program | Discovery of nuclear fission
Hahn, initially, was not, but he changed his mind when Aristid von Grosse suggested that what Fermi had found was an isotope of protactinium. "The only question", Hahn later wrote, "seemed to be whether Fermi had found isotopes of transuranian elements, or isotopes of the next-lower element, protactinium. At that time Lise Meitner and I decided to repeat Fermi's experiments in order to find out whether the 13-minute isotope was a protactinium isotope or not. It was a logical decision, having been the discoverers of protactinium." Between 1934 and 1938, Hahn, Meitner and Strassmann found a great number of radioactive transmutation products, all of which they regarded as transuranic.
Otto Hahn | Discovery of nuclear fission
With the discovery of protactinium, most of the decay chains of uranium had been mapped. When Hahn returned to his work after the war, he looked back over his 1914 results, and considered some anomalies that had been dismissed or overlooked. He dissolved uranium salts in a hydrofluoric acid solution with tantalic acid. First the tantalum in the ore was precipitated, then the protactinium. In addition to the uranium X1 (thorium-234) and uranium X2 (protactinium-234), Hahn detected traces of a radioactive substance with a half life of between 6 and 7 hours. There was one isotope known to have a half life of 6.2 hours, mesothorium II (actinium-228).
Otto Hahn | Discovery of nuclear isomerism
At this point, Hahn decided that he first needed to know more about the subject, so he wrote to the leading expert on the field, Ernest Rutherford. Rutherford agreed to take Hahn on as an assistant, and Hahn's parents undertook to pay Hahn's expenses. From September 1905 until mid-1906, Hahn worked with Rutherford's group in the basement of the Macdonald Physics Building at McGill University in Montreal. There was some scepticism about the existence of radiothorium, which Bertram Boltwood memorably described as a compound of thorium X and stupidity. Boltwood was soon convinced that it did exist, although he and Hahn differed on what its half life was.
Otto Hahn | Discovery of radio thorium, and other "new elements"
She considered the possibility that the reactions were from different isotopes of uranium; three were known: uranium-238, uranium-235 and uranium-234. However, when she calculated the neutron cross section, it was too large to be anything other than the most abundant isotope, uranium-238. She concluded that it must be another case of the nuclear isomerism that Hahn had discovered in protactinium. She therefore ended her report on a very different note to Hahn, reporting that: "The process must be neutron capture by uranium-238, which leads to three isomeric nuclei of uranium-239. This result is very difficult to reconcile with current concepts of the nucleus."
Otto Hahn | Discovery of nuclear fission
During the Christmas holiday in 1938 he visited his aunt Lise Meitner in Kungälv. While there she received the news that Otto Hahn and Fritz Strassmann in Berlin had discovered that the collision of a neutron with a uranium nucleus produced the element barium as one of its byproducts. Hahn, in a letter to Meitner, called this new reaction a "bursting" of the uranium nucleus. Frisch and Meitner hypothesized that the uranium nucleus had split in two, explained the process, and estimated the energy released, and Frisch coined the term fission to describe it. Political restraints of the Nazi era forced the team of Hahn and that of Frisch and Meitner (both of whom were Jewish) to publish separately.
Otto Robert Frisch | Nuclear fission
His wife Edith only survived him by a fortnight. He was buried in the Stadtfriedhof in Göttingen. The day after his death, the Max Planck Society published the following obituary notice in all the major newspapers in Germany, Austria, and Switzerland: Fritz Strassmann wrote: Otto Robert Frisch recalled:
Otto Hahn | Death
Initially, Hahn was not interested, but von Grosse's mention of protactinium changed his mind. "The only question", Hahn later wrote, "seemed to be whether Fermi had found isotopes of transuranian elements, or isotopes of the next-lower element, protactinium. At that time Lise Meitner and I decided to repeat Fermi's experiments in order to find out whether the 13-minute isotope was a protactinium isotope or not. It was a logical decision, having been the discoverers of protactinium." Hahn and Meitner were joined by Fritz Strassmann. Strassmann had received his doctorate in analytical chemistry from the Technical University of Hannover in 1929, and had come to the Kaiser Wilhelm Institute for Chemistry to study under Hahn, believing that this would improve his employment prospects.
Discovery of nuclear fission | Objections
They identified ten different half lives, with varying degrees of certainty. To account for them, Meitner had to hypothesise a new class of reaction and the alpha decay of uranium, neither of which had ever been reported before, and for which physical evidence was lacking. Hahn and Strassmann refined their chemical procedures, while Meitner devised new experiments to shine more light on the reaction processes. In May 1937, they issued parallel reports, one in "Zeitschrift für Physik" with Meitner as the principal author, and one in "Chemische Berichte" with Hahn as the principal author. Hahn concluded his by stating emphatically: "Vor allem steht ihre chemische Verschiedenheit von allen bisher bekannten Elementen außerhalb jeder Diskussion" ("Above all, their chemical distinction from all previously known elements needs no further discussion"); Meitner was increasingly uncertain.
Otto Hahn | Discovery of nuclear fission
After James Chadwick discovered the neutron in 1932, Irène Curie and Frédéric Joliot irradiated aluminium foil with alpha particles, they found that this results in a short-lived radioactive isotope of phosphorus. They noted that positron emission continued after the neutron emissions ceased. Not only had they discovered a new form of radioactive decay, they had transmuted an element into a hitherto unknown radioactive isotope of another, thereby inducing radioactivity where there had been none before. Radiochemistry was now no longer confined to certain heavy elements, but extended to the entire periodic table. Chadwick noted that being electrically neutral, neutrons could penetrate the atomic nucleus more easily than protons or alpha particles.
Otto Hahn | Discovery of nuclear fission
That summer Hahn was accidentally poisoned by phosgene while testing a new model gas mask. At the end of the war he was in the field in mufti on a secret mission to test a pot that heated and released a cloud of arsenicals.
Otto Hahn | World War I
William Henry Bragg and Richard Kleeman had noted that the alpha particles emitted from radioactive substances always had the same energy, providing a second way of identifying them, so Hahn set about measuring the alpha particle emissions of radiothorium. In the process, he found that a precipitation of thorium A (polonium-216) and thorium B (lead-212) also contained a short-lived "element", which he named thorium C (which was later identified as polonium-212). Hahn was unable to separate it, and concluded that it had a very short half life (it is about 300 ns). He also identified radioactinium (thorium-227) and radium D (later identified as lead-210).
Otto Hahn | Discovery of radio thorium, and other "new elements"
He was transferred to Berlin as a human Guinea-pig testing poisonous gases and gas masks. On their next attempt on 7 July, the gas again blew back on German lines, and Hertz was poisoned. This assignment was interrupted by a mission at the front in Flanders and again in 1916 by a mission to Verdun to introduce shells filled with phosgene to the Western Front. Then once again he was hunting along both fronts for sites for gas attacks. In December 1916 he joined the new gas command unit at Imperial Headquarters. Between operations, Hahn returned to Berlin, where he was able to slip back to his old laboratory and assist Meitner with her research.
Otto Hahn | World War I
To ensure that their clean new laboratories stayed that way, Hahn and Meitner instituted strict procedures. Chemical and physical measurements were conducted in different rooms, people handling radioactive substances had to follow protocols that included not shaking hands, and rolls of toilet paper were hung next to every telephone and door handle. Strongly radioactive substances were stored in the old wood shop, and later in a purpose-built radium house on the institute grounds.
Otto Hahn | Discovery of radioactive recoil
Not only Hahn but most of the students, laboratory assistants and technicians had been called up, so she had to do everything herself, aided only briefly by Hahn when he came home on leave. By December 1917 she was able to isolate the substance, and after further work was able to prove that it was indeed the missing isotope. She submitted their findings for publication in March 1918. Although Fajans and Göhring had been the first to discover the element, custom required that an element was represented by its longest-lived and most abundant isotope, and brevium did not seem appropriate.
Otto Hahn | Discovery of protactinium
The German chemist Ida Noddack notably suggested in print in 1934 that instead of creating a new, heavier element 93, that "it is conceivable that the nucleus breaks up into several large fragments." However, Noddack's conclusion was not pursued at the time. After the Fermi publication, Otto Hahn, Lise Meitner, and Fritz Strassmann began performing similar experiments in Berlin. Meitner, an Austrian Jew, lost her Austrian citizenship with the "Anschluss", the union of Austria with Germany in March 1938, but she fled in July 1938 to Sweden and started a correspondence by mail with Hahn in Berlin. By coincidence, her nephew Otto Robert Frisch, also a refugee, was also in Sweden when Meitner received a letter from Hahn dated 19 December describing his chemical proof that some of the product of the bombardment of uranium with neutrons was barium.
Nuclear fission | Discovery of nuclear fission
Based on the radioactive displacement law of Fajans and Soddy, this was an isotope of the missing element, which they named "brevium" after its short half life. However, it was a beta emitter, and therefore could not be the mother isotope of actinium. This had to be another isotope of the same element. Hahn and Meitner set out to find the missing mother isotope. They developed a new technique for separating the tantalum group from pitchblende, which they hoped would speed the isolation of the new isotope. The work was interrupted by the First World War. Meitner became an X-ray nurse, working in Austrian Army hospitals, but she returned to the Kaiser Wilhelm Institute in October 1916.
Otto Hahn | Discovery of protactinium
This was not in any probable decay chain, but it could have been contamination, as the Kaiser Wilhelm Institute for Chemistry had experimented with it. Hahn and Meitner demonstrated in 1919 that when actinium is treated with hydrofluoric acid, it remains in the insoluble residue. Since mesothorium II was an isotope of actinium, the substance was not mesothorium II; it was protactinium. Hahn was now confident enough that he had found something that he named his new isotope "uranium Z", and in February 1921, he published the first report on his discovery. Hahn determined that uranium Z had a half life of around 6.7 hours (with a two per cent margin of error) and that when uranium X1 decayed, it became uranium X2 about 99.75 per cent of the time, and uranium Z around 0.25 per cent of the time.
Otto Hahn | Discovery of nuclear isomerism
Hahn and Strassmann at the Kaiser Wilhelm Institute for Chemistry in Berlin bombarded uranium with slow neutrons, and discovered that barium had been produced. They reported their findings by mail to Meitner in Sweden, who a few months earlier had fled Nazi Germany. Meitner and her nephew Frisch theorised, and then proved, that the uranium nucleus had been split, and published their findings in "Nature". Meitner calculated that the energy released by each disintegration was approximately 200 megaelectronvolts, and Frisch observed this. By analogy with the division of biological cells, he named the process "fission". Hahn was awarded the 1944 Nobel Prize in Chemistry for the discovery.
Discovery of nuclear fission | Introduction
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. They established the presence of multiple isotopes of at least four such elements, and (mistakenly) identified them as elements with atomic numbers 93 through 96. They were the first scientists to measure the 23-minute half life of uranium-239 and to establish chemically that it was an isotope of uranium, but were unable to continue this work to its logical conclusion and identify the real element 93.
Otto Hahn | Discovery of nuclear fission
During the Christmas holiday in 1938, Frisch visited his aunt Lise Meitner in Kungälv in Sweden, where she had relocated after Germany's annexation of Austria. While there she received the news that her former colleagues Otto Hahn and Fritz Strassmann in Berlin had discovered that the collision of a neutron with a uranium nucleus produced barium as one of its byproducts. Frisch and Meitner hypothesized that the uranium nucleus had split in two. They estimated the energy released at around 200 MeV, and Frisch appropriated the term fission from biology to describe it. Hahn's paper described the experiment and the finding of the barium byproduct.
Frisch–Peierls memorandum | Nuclear fission
He found that the proportion of uranium X to uranium Z extracted from several kilograms of uranyl nitrate remained constant over time, strongly indicating that uranium X was the mother of uranium Z. To prove this, Hahn obtained a hundred kilograms of uranyl nitrate; separating the uranium X from it took weeks. He found that the half life of the parent of uranium Z differed from the known 24 day half life of uranium X1 by no more than two or three days, but was unable to get a more accurate value. Hahn concluded that uranium Z and uranium X2 were both the same isotope of protactinium (protactinium-234), and they both decayed into uranium II (uranium-234), but with different half lives.
Otto Hahn | Discovery of nuclear isomerism
The new laboratories offered new opportunities, as the old ones had become too contaminated with radioactive substances to investigate feebly radioactive substances. They developed a new technique for separating the tantalum group from pitchblende, which they hoped would speed the isolation of the new isotope. The work was interrupted by the outbreak of the First World War in 1914. Hahn was called up into the German Army, and Meitner became a volunteer radiographer in Austrian Army hospitals. She returned to the Kaiser Wilhelm Institute in October 1916, when not only Hahn, but most of the students, laboratory assistants and technicians had been called up.
Discovery of nuclear fission | Protactinium
Enrico Fermi and his colleagues in Rome picked up on this idea, and began irradiating elements with neutrons. The radioactive displacement law of Fajans and Soddy said that beta decay causes isotopes to move one element up on the periodic table, and alpha decay causes them to move two down. When Fermi's group bombarded uranium atoms with neutrons, they found a complex mix of half lives. Fermi therefore concluded that the new elements with atomic numbers greater than 92 (known as transuranium elements) had been created. Meitner and Hahn had not collaborated for many years, but Meitner was eager to investigate Fermi's results.
Otto Hahn | Discovery of nuclear fission
Uranium Z was the first example of nuclear isomerism. Walther Gerlach later remarked that this was "a discovery that was not understood at the time but later became highly significant for nuclear physics". Not until 1936 was Carl Friedrich von Weizsäcker able to provide a theoretical explanation of the phenomenon. For this discovery, whose full significance was recognised by very few, Hahn was again proposed for the Nobel Prize in Chemistry by Bernhard Naunyn, Goldschmidt and Planck.
Otto Hahn | Discovery of nuclear isomerism
Over the following days they were joined by Kurt Diebner, Walther Gerlach, Paul Harteck and Werner Heisenberg. All were physicists except Hahn and Harteck, who were chemists, and all had worked on the German nuclear weapons program except von Laue, although he was well aware of it. They were relocated to the Château de Facqueval in Modave, Belgium, where Hahn used the time to work on his memoirs and then, on 3 July, were flown to England. They arrived at Farm Hall, Godmanchester, near Cambridge, on 3 July. Unbeknown to them, their every conversation, indoors and out, was recorded from hidden microphones.
Otto Hahn | Incarceration
The Kaiser Wilhelm Institute for Chemistry, now under Strassmann, built and renovated new accommodation in Mainz, but work proceeded slowly, and it did not relocate from Tailfingen until 1949. Hahn's insistence on retaining Ernst Telschow as the general secretary nearly caused a rebellion against his presidency. In his efforts to rebuild German science, Hahn was generous in issuing "persilschein" (whitewash certificates), writing one for Gottfried von Droste, who had joined the "Sturmabteilung" (SA) in 1933 and the NSDAP in 1937, and wore his SA uniform at the Kaiser Wilhelm Institute for Chemistry, and for Heinrich Hörlein and Fritz ter Meer from IG Farben.
Otto Hahn | Founder and President of the Max Planck Society
Hahn was shot in the back by a disgruntled inventor in October 1951, injured in a motor vehicle accident in 1952, and had a minor heart attack in 1953. In 1962, he published a book, "Vom Radiothor zur Uranspaltung". It was released in English in 1966 with the title "Otto Hahn: A Scientific Autobiography", with an introduction by Glenn Seaborg. The success of this book may have prompted him to write another, fuller autobiography, "Otto Hahn. Mein Leben", but before it could be published, he fractured one of the vertebrae in his neck while getting out of a car. He gradually became weaker and died in Göttingen on 28 July 1968.
Otto Hahn | Death
In 1906, he returned to Germany, where he became an assistant to Emil Fischer at the University of Berlin. At McGill he had become accustomed to working closely with a physicist, so he teamed up with Lise Meitner, who had received her doctorate from the University of Vienna in 1906, and had then moved to Berlin to study physics under Max Planck at the Friedrich-Wilhelms-Universität. Meitner found Hahn, who was her own age, less intimidating than older, more distinguished colleagues. Hahn and Meitner moved to the recently established Kaiser Wilhelm Institute for Chemistry in 1913, and by 1920 had become the heads of their own laboratories there, with their own students, research programs and equipment.
Discovery of nuclear fission | Protactinium
Hahn's paper described the experiment and the finding of the barium byproduct. Meitner's and Frisch's paper explained the physics behind the phenomenon. Frisch went back to Copenhagen, where he was quickly able to isolate the pieces produced by fission reactions. As Frisch himself later recalled, a fundamental idea of the direct experimental proof of the nuclear fission was suggested to him by George Placzek. Many feel that Meitner and Frisch deserved Nobel Prize recognition for their contributions to understanding fission.
Otto Robert Frisch | Nuclear fission
Hahn was still there when his Nobel Prize was announced in November 1945. The Farm Hall scientists would spend the rest of their lives attempting to rehabilitate the image of German science that had been tarnished by the Nazi period. Inconvenient details like the thousands of female slave labourers from Sachsenhausen concentration camp who mined uranium ore for their experiments were swept under the rug. For Hahn, this necessarily involved asserting his claim of the discovery of fission for himself, for chemistry, and for Germany. He used his Nobel Prize acceptance speech to assert this narrative. Hahn's message resonated strongly in Germany, where he was revered as the proverbial good German, a decent man who had been a staunch opponent of the Nazi regime, but had remained in Germany where he had pursued pure science.
Discovery of nuclear fission | In history and memory
He was a guest teacher at the University of Michigan, the State University of New York, the University of Paris and the University of Zurich, as well as being active in research, excavation and public relations. He led excavations in the Ach Valley and the caves of the Swabian Alb, where important discoveries were made, and he worked with some of the oldest man-made works of art. His publications number over 100. In 1997, at age 54, he died of complications of cancer.
Joachim Hahn | Introduction
It was not long before Fajans and Oswald Helmuth Göhring discovered it as a decay product of a beta-emitting product of thorium. Based on the radioactive displacement law of Fajans and Soddy, this was an isotope of the missing element, which they named "brevium" after its short half-life. However, it was a beta emitter, and therefore could not be the mother isotope of actinium. This had to be another isotope. Two scientists at the Kaiser Wilhelm Institute (KWI) in Berlin-Dahlem took up the challenge of finding the missing isotope. Otto Hahn had graduated from the University of Marburg as an organic chemist, but had been a post-doctoral researcher at University College London under Sir William Ramsay, and under Rutherford at McGill University, where he had studied radioactive isotopes.
Discovery of nuclear fission | Protactinium
Hahn reported to the HWA on the progress of his research. Together with his assistants, Hans-Joachim Born, Siegfried Flügge, Hans Götte, Walter Seelmann-Eggebert and Strassmann, he catalogued about one hundred fission product isotopes. They also investigated means of isotope separation; the chemistry of element 93; and methods for purifying uranium oxides and salts. On the night of 15 February 1944, the Kaiser Wilhelm Institute for Chemistry building was struck by a bomb. Hahn's office was destroyed, along with his correspondence with Rutherford and other researchers, and many of his personal possessions. The office was the intended target of the raid, which had been ordered by Brigadier General Leslie Groves, the director of the Manhattan Project, in the hope of disrupting the German uranium project.
Otto Hahn | World War II
In 1924, Hahn was elected to full membership of the Prussian Academy of Sciences in Berlin, by a vote of thirty white balls to two black. While still remaining the head of his own department, he hecame Deputy Director of the Kaiser Wilhelm Institute for Chemistry in 1924, and succeeded Alfred Stock as the director in 1928. Meitner became the director of the Physical Radioactivity Division, while Hahn headed the Chemical Radioactivity Division. In the early 1920s, he created a new line of research. 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.
Otto Hahn | "Applied Radiochemistry"
Otto Hahn was born in Frankfurt am Main on 8 March 1879, the youngest son of Heinrich Hahn (1845–1922), a prosperous glazier (and founder of the Glasbau Hahn company), and Charlotte Hahn Giese (1845–1905). He had an older half-brother Karl, his mother's son from her previous marriage, and two older brothers, Heiner and Julius. The family lived above his father's workshop. The younger three boys were educated at "Klinger Oberrealschule" in Frankfurt. 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.
Otto Hahn | Early life
Wilhelm Röntgen discovered X-rays. Otto Hahn was a pioneer in the fields of radiochemistry and discovered nuclear fission, while Ferdinand Cohn and Robert Koch were founders of microbiology.
List of German inventions and discoveries | Introduction
On 25 April 1945, an armoured task force from the Alsos Mission arrived in Tailfingen, and surrounded the Kaiser Wilhelm Institute for Chemistry. Hahn was informed that he was under arrest. When asked about reports related to his secret work on uranium, Hahn replied: "I have them all here", and handed over 150 reports. He was taken to Hechingen, where he joined Erich Bagge, Horst Korsching, Max von Laue, Carl Friedrich von Weizsäcker and Karl Wirtz. They were then taken to a dilapidated château in Versailles, where they heard about the signing of the German Instrument of Surrender at Reims on 7 May.
Otto Hahn | Incarceration
In 1897, after taking his "Abitur", Hahn began to study chemistry at the University of Marburg. His subsidiary subjects were mathematics, physics, mineralogy and philosophy. Hahn joined the Students' Association of Natural Sciences and Medicine, a student fraternity and a forerunner of today's "Landsmannschaft Nibelungi" (Coburger Convent der akademischen Landsmannschaften und Turnerschaften). He spent his third and fourth semesters at the University of Munich, studying organic chemistry under Adolf von Baeyer, physical chemistry under Friedrich Wilhelm Muthmann, and inorganic chemistry under Karl Andreas Hofmann. In 1901, Hahn received his doctorate in Marburg for a dissertation entitled "On Bromine Derivates of Isoeugenol", a topic in classical organic chemistry.
Otto Hahn | Early life
For more details of the original discovery of nuclear fission see the work of Otto Hahn.
Nuclear chemistry | Study of nuclear reactions
Otto Schoetensack (; July 12, 1850 in Stendal – December 23, 1912 in Ospedaletti) was a German industrialist and later professor of anthropology, having retired from the chemical firm which he had founded. During a 1908 archeological dig, he oversaw the worker Daniel Hartmann who found the lower jaw of a hominid, the oldest human fossil then known, which Schoetensack later described formally as "Homo heidelbergensis."
Otto Schoetensack | Introduction
On 16 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." Hahn was still 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 on 18 November through the "Daily Telegraph". His fellow interned scientists celebrated his award by giving speeches, making jokes, and composing songs. Hahn had been nominated for the chemistry and the physics Nobel prizes many times even before the discovery of nuclear fission.
Otto Hahn | The Nobel Prize in Chemistry 1944
For the explanation of their behaviour he collaborated with the physicist Otto Lehmann from Aachen. The discovery received plenty of attention at the time but no practical uses were apparent and the interest dropped soon.
Friedrich Reinitzer | Introduction
In mid-1936, Heisenberg presented his theory of cosmic-ray showers in two papers. Four more papers appeared in the next two years. In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to "The Natural Sciences" reporting they had detected the element barium after bombarding uranium with neutrons and Otto Hahn concluded a "bursting" of the uranium nucleus; simultaneously, Hahn communicated these results to his friend Lise Meitner, who had in July of that year fled to the Netherlands and then went to Sweden. Meitner, and her nephew Otto Robert Frisch, correctly interpreted Hahn's and Strassmann's results as being nuclear fission.
Werner Heisenberg | Pre-war work on physics
Hahn noted that he was glad that they had not succeeded, and von Weizsäcker suggested that they should claim that they had not wanted to. They drafted a memorandum on the project, noting that fission was discovered by Hahn and Strassmann. The revelation that Nagasaki had been destroyed by a plutonium bomb came as another shock, as it meant that the Allies had not only been able to successfully conduct uranium enrichment, but had mastered nuclear reactor technology as well. The memorandum became the first draft of a postwar apologia. The idea that Germany had lost the war because its scientists were morally superior was as outrageous as it was unbelievable, but struck a chord in postwar German academia.
Otto Hahn | Incarceration
Their only child, , was born on 9 April 1922. During World War II, he enlisted in the army in 1942, and served with distinction on the Eastern Front as a panzer commander. He lost an arm in combat. After the war he became a distinguished art historian and architectural researcher (at the Hertziana in Rome), known for his discoveries in the early Cistercian architecture of the 12th century. In August 1960, while on a study trip in France, Hanno died in a car accident, together with his wife and assistant Ilse Hahn Pletz. They left a fourteen-year-old son, Dietrich Hahn.
Otto Hahn | Marriage to Edith Junghans
Frisch confirmed this experimentally on January 13, 1939. In 1944, Hahn received the Nobel Prize for Chemistry for the discovery of nuclear fission. Some historians have documented the history of the discovery of nuclear fission and believe Meitner should have been awarded the Nobel Prize with Hahn.
Herbert L. Anderson | Education
In 1938, a team of German scientists, led by Otto Hahn, decided to investigate Fermi's bold claim. Unfortunately for Fermi, they quickly disproved his assertion; one of the elements produced was barium, which, with 56 protons, was nowhere near the 92 protons the nucleus started with when it was uranium. Hahn wrote of his confusion to his colleague Lisa Meitner who, as an Austrian Jew, had recently fled Nazi Germany for Sweden.
Chemistry: A Volatile History | Otto Hahn disproves Fermi’s claims
In 1938, the German chemist Otto Hahn, a student of Rutherford, directed neutrons onto uranium atoms expecting to get transuranium elements. Instead, his chemical experiments showed barium as a product. A year later, Lise Meitner and her nephew Otto Frisch verified that Hahn's result were the first experimental "nuclear fission". In 1944, Hahn received the Nobel Prize in Chemistry. Despite Hahn's efforts, the contributions of Meitner and Frisch were not recognized. In the 1950s, the development of improved particle accelerators and particle detectors allowed scientists to study the impacts of atoms moving at high energies. Neutrons and protons were found to be hadrons, or composites of smaller particles called quarks.
Atom | Fission, high-energy physics and condensed matter
Rubens said that he would be happy for her to work in his laboratory. He also added that Otto Hahn at the chemistry institute was looking for a physicist to collaborate with. A few minutes later she was introduced to Hahn. He had studied radioactive substances under Sir William Ramsay, and in Montreal under Rutherford, and was already credited with the discovery of what were then thought to be several new radioactive elements. (In fact, they were isotopes of known elements, but the concept of an isotope, along with the term, was only propounded by Frederick Soddy in 1913.) Hahn was the same age as herself, and she noted his informal and approachable manner.
Lise Meitner | Friedrich Wilhelm University
Hanle and Joos would soon be part of the impetus to initiate the German nuclear energy project, shortly after Hanle went to Göttingen. From 1937 to 1941, Hanle was again at the University of Göttingen. In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to "Naturwissenschaften" reporting they had detected the element barium after bombarding uranium with neutrons; simultaneously, they communicated these results to Lise Meitner, who had in July of that year fled to The Netherlands and then went to Sweden. Meitner, and her nephew Otto Robert Frisch, correctly interpreted these results as being nuclear fission.
Wilhelm Hanle | Career
The result was surprising because of the large difference in atomic number of the two elements, uranium having atomic number 92 and barium having atomic number 56. In December 1938, Hahn and Strassmann sent a manuscript to "Naturwissenschaften" reporting the results of their experiments on detection of barium as a product of neutron bombardment of uranium Otto Frisch confirmed Strassman and Hahn's report experimentally on 13 January 1939. Frisch and Meitner explained Strassman's and Hahn's findings as being from nuclear fission.
Fritz Strassmann | Career
On returning to Copenhagen, Frisch informed Bohr, who slapped his forehead and exclaimed "What idiots we have been!" Bohr promised not to say anything until they had a paper ready for publication. To speed the process, they decided to submit a one-page note to "Nature". At this point, the only evidence that they had was the barium. Logically, if barium was formed, the other element must be krypton, although Hahn mistakenly believed that the atomic masses had to add up to 239 rather than the atomic numbers adding up to 92, and thought it was masurium (technetium), and so did not check for it: Over a series of long-distance phone calls, Meitner and Frisch came up with a simple experiment to bolster their claim: to measure the recoil of the fission fragments, using a Geiger counter with the threshold set above that of the alpha particles.
Discovery of nuclear fission | Eureka!
Hahn therefore became the sole recipient of the 1944 Nobel Prize in Chemistry "for his discovery of the fission of heavy nuclei".
Discovery of nuclear fission | Nobel Prize
He was an honorary fellow of University College London,
Otto Hahn | Honors and awards
Hahn was a Boy Scout fascinated by chemistry, and spent years conducting amateur chemistry experiments, which sometimes caused small explosions and other mishaps. He was inspired in part by reading "The Golden Book of Chemistry Experiments", and tried to collect samples of every element in the periodic table, including the radioactive ones. He later received a merit badge in Atomic Energy and became fascinated with the idea of creating a breeder reactor in his home. Hahn diligently amassed radioactive material by collecting small amounts from household products, such as americium from smoke detectors, thorium from camping lantern mantles, radium from clocks, and tritium from gunsights.
David Hahn | Creation of the neutron source
In 1936 Cornell University Press published a book in English (and later in Russian) titled "Applied Radiochemistry", which contained the lectures given by Hahn when he was a visiting professor at Cornell University in Ithaca, New York, in 1933. This important publication had a major influence on almost all nuclear chemists and physicists in the United States, the United Kingdom, France, and the Soviet Union during the 1930s and 1940s. In 1966, Glenn T. Seaborg, co-discoverer of many transuranium elements, wrote about this book as follows:
Otto Hahn | "Applied Radiochemistry"
Friedrich Wilhelm "Fritz" Strassmann (; 22 February 1902 – 22 April 1980) was a German chemist who, with Otto Hahn in early 1939, identified the element barium as a product of the bombardment of uranium with neutrons. Their observation was the key piece of evidence necessary to identify the previously unknown phenomenon of nuclear fission, as was subsequently recognized and published by Lise Meitner and Otto Frisch.
Fritz Strassmann | Introduction
This article is based on a translation of the equivalent article on German Wikipedia
Otto Hahn Prize | References
Harriet Brooks observed a radioactive recoil in 1904, but interpreted it wrongly. Hahn and Meitner succeeded in demonstrating the radioactive recoil incident to alpha particle emission and interpreted it correctly. Hahn pursued a report by Stefan Meyer and Egon Schweidler of a decay product of actinium with a half-life of about 11.8 days. Hahn determined that it was actinium X (radium-223). Moreover, he discovered that at the moment when a radioactinium (thorium-227) atom emits an alpha particle, it does so with great force, and the actinium X experiences a recoil. This is enough to free it from chemical bonds, and it has a positive charge, and can be collected at a negative electrode.
Otto Hahn | Discovery of radioactive recoil
Albert Speer, the Reich Minister of Armaments and War Production, arranged for the institute to move to Tailfingen in southern Germany. All work in Berlin ceased by July. Hahn and his family moved to the house of a textile manufacturer there. Life became precarious for those married to Jewish women. One was Philipp Hoernes, a chemist working for Auergesellschaft, the firm that mined the uranium ore used by the project. After the firm let him go in 1944, Hoernes faced being conscripted for forced labour. At the age of 60, it was doubtful that he would survive. Hahn and Nikolaus Riehl arranged for Hoernes to work at the Kaiser Wilhelm Institute for Chemistry, claiming that his work was essential to the uranium project and that uranium was highly toxic, making it hard to find people to work with it.
Otto Hahn | World War II
He enjoyed the work and the people so much that he stayed on after his stipend expired in 1932. After the Nazi Party came to power in Germany in 1933, he declined a lucrative offer of employment because it required political training and Nazi Party membership, and he resigned from the Society of German Chemists when it became part of the Nazi German Labour Front. As a result, he could neither work in the chemical industry nor receive his habilitation, which was required to become an independent researcher in Germany. Meitner persuaded Hahn to hire Strassmann using money from the director's special circumstances fund.
Discovery of nuclear fission | Objections
Hahn was aware that uranium ore was fairly safe in the laboratory, although not so much for the 2,000 female slave labourers from Sachsenhausen concentration camp who mined it in Oranienburg—for other reasons. Another physicist with a Jewish wife was . Hahn certified that his work was important to the war effort, and that his wife Maria, who had a doctorate in physics, was required as his assistant. After he died on 19 September 1944, Maria faced being sent to a concentration camp. Hahn mounted a lobbying campaign to get her released, but to no avail, and she was sent to the Theresienstadt Ghetto in January 1945.
Otto Hahn | World War II
He completed his one-year military service (instead of the usual two because he had a doctorate) in the 81st Infantry Regiment, but unlike his brothers, did not apply for a commission. He then returned to the University of Marburg, where he worked for two years as assistant to his doctoral supervisor, "Geheimrat" Professor Theodor Zincke.
Otto Hahn | Early life
• Biographischer Eintrag in the Online-Documentation of the anthroposophical Forschungsstelle Kulturimpuls
Herbert Hahn | External links
Meitner received the letter from Hahn describing his chemical proof that some of the product of the bombardment of uranium with neutrons was barium. Barium had an atomic mass 40% less than uranium, and no previously known methods of radioactive decay could account for such a large difference in the mass of the nucleus. Nonetheless, she had immediately written back to Hahn to say: "At the moment the assumption of such a thoroughgoing breakup seems very difficult to me, but in nuclear physics we have experienced so many surprises, that one cannot unconditionally say: 'It is impossible.'" Meitner felt that Hahn was too careful a chemist to make an elementary blunder, but found the results difficult to explain.
Discovery of nuclear fission | Eureka!
On 19 December, Hahn wrote to Meitner, informing her that the radium isotopes behaved chemically like barium. Anxious to finish up before the Christmas break, Hahn and Strassmann submitted their findings to "Naturwissenschaften" on 22 December without waiting for Meitner to reply. Hahn concluded with: "As chemists... we should substitute the symbols Ba, La, Ce for Ra, Ac, Th. As 'nuclear chemists' fairly close to physics we cannot yet bring ourselves to take this step which contradicts all previous experience in physics." Frisch normally celebrated Christmas with Meitner in Berlin, but in 1938 she accepted an invitation from Eva von Bahr to spend it with her family at Kungälv, and Meitner asked Frisch to join her there.
Discovery of nuclear fission | Eureka!
In 1913, chemists Frederick Soddy and Kasimir Fajans independently observed that alpha decay caused atoms to shift down two places on the periodic table, while the loss of two beta particles restored it to its original position. Under the resulting reorganisation of the periodic table, radium was placed in group II, actinium in group III, thorium in group IV and uranium in group VI. This left a gap between thorium and uranium. Soddy predicted that this unknown element, which he referred to (after Dmitri Mendeleev) as "ekatantalium", would be an alpha emitter with chemical properties similar to tantalium. It was not long before Fajans and Oswald Helmuth Göhring discovered it as a decay product of a beta-emitting product of thorium.
Otto Hahn | Discovery of protactinium
Otto Hahn (1828 – 1904) was a German petrologist, geologist, lawyer and author. His father was Johann Franz Gottlieb Hahn (1789 – 1844). His great-grandfather was Christian Tobias Hahn (1759 – 1837), who was the half-brother of Philipp Matthäus Hahn. Hahn started his career as a lawyer. He eventually left the legal profession for the natural sciences. The University of Tübingen awarded him a doctorate for his participation in the Eozoön canadense controversy. He was an active member of The New Church (Swedenborgian) and was a Neptunist. He published "Die Urzelle" in 1879. His book "Die Meteorite (Chondrite) und ihre Organismen", published the following year in 1880, was a major work in the field of meteoritics that included 142 black and white photomicrographs of chondrite thin sections.
Otto Hahn (petrologist) | Introduction
While Hahn was in North America, his attention was drawn to a mica-like mineral from Manitoba that contained rubidium. Some years before he had studied the radioactive decay of rubidium-87, and had estimated its half life at 2 x 10 years. It occurred to Hahn that by comparing the quantity of strontium in the mineral (which had once been rubidium) with that of the remaining rubidium, he could measure the age of the mineral, assuming that his original calculation of the half life was reasonably accurate. This would be a superior dating method to studying the decay of uranium, because some of the uranium turns into helium, which then escapes, resulting in rocks appearing to be younger than they really were.
Otto Hahn | Rubidium–strontium dating
Otto Robert Frisch was born in Vienna in 1904. He studied physics at the University of Vienna, from which he received his DPhil in 1926. He worked at the Physikalisch-Technische Reichsanstalt in Berlin until 1930, when he obtained a position at the University of Hamburg under the Nobel Prize-winning scientist Otto Stern. As non-Aryans, Stern and Frisch were dismissed after Hitler's accession. Stern found Frisch a position in Britain with Patrick Blackett at Birkbeck College at the University of London, and a grant from the Academic Assistance Council. He followed this with a five-year stint at the Niels Bohr Institute in Copenhagen with Niels Bohr where he increasingly specialised in nuclear physics, particularly the physics of neutrons, which had been discovered by James Chadwick in 1932.
Frisch–Peierls memorandum | Otto Frisch
They were given British newspapers, which Hahn was able to read. He was greatly disturbed by their reports of the Potsdam Conference, where German territory was ceded to Poland and the USSR. In August 1945, the German scientists were informed of the atomic bombing of Hiroshima. Up to this point the scientists, except Harteck, were completely certain that their project was further advanced than any in other countries, and the Alsos Mission's chief scientist, Samuel Goudsmit, did nothing to correct this impression. Now the reason for their incarceration in Farm Hall suddenly became apparent. As they recovered from the shock of the announcement, they began to rationalise what had happened.
Otto Hahn | Incarceration
Meitner, and her nephew Otto Robert Frisch, Discovery of fission}}correctly interpreted these results as being nuclear fission. Frisch confirmed this experimentally on 13 January 1939. Droste and Siegfried Flügge, an assistant to Hahn, independently also predicted a large energy release from nuclear fission.
Gottfried von Droste | Career
News of the discovery of nuclear fission by German chemists Otto Hahn and Fritz Strassmann in 1938, and its theoretical explanation by Lise Meitner and Otto Frisch, was brought to the United States by Niels Bohr. Based on his liquid drop model of the nucleus, he theorized that it was the uranium-235 isotope and not the more abundant uranium-238 that was primarily responsible for fission with thermal neutrons. To verify this Alfred O. C. Nier at the University of Minnesota used a mass spectrometer to create a microscopic amount of enriched uranium-235 in April 1940. John R. Dunning, Aristid von Grosse and Eugene T.
Calutron | Origins
Kurt Otto Friedrich Hense (11 April 1845, Halberstadt – 11 March 1931, Freiburg im Breisgau) was a German classical philologist known for his investigations of Sophocles and the anthologist Stobaeus. In 1868 he obtained his doctorate from the University of Halle with the dissertation thesis, "Exercitationes criticae imprimis in Euripidis fragmentis". After graduation, he worked as a gymnasium teacher, and in 1872 received his habilitation for classical philology at the University of Halle. From 1876 to 1909 he was a professor at the University of Freiburg, where in 1893/94 he served as university vice-rector.
Otto Hense | Introduction
The Paris group published their results in September 1938. Hahn dismissed the isotope with the 3.5-hour half-life as contamination, but after looking at the details of the Paris group's experiments and the decay curves, Strassmann was worried. He decided to repeat the experiment, using his more efficient method of separating radium. This time, they found what they thought was radium, which Hahn suggested resulted from two alpha decays: Meitner found this very hard to believe. In November, Hahn travelled to Copenhagen, where he met with Bohr and Meitner. They told him that they were very unhappy about the proposed radium isomers.
Discovery of nuclear fission | Eureka!
Fajans agreed to Meitner naming the element protoactinmium, and assigning it the chemical symbol Pa. In June 1918, Soddy and John Cranston announced that they had extracted a sample of the isotope, but unlike Meitner were unable to describe its characteristics. They acknowledged Meitner's priority, and agreed to the name. The connection to uranium remained a mystery, as neither of the known isotopes of uranium decayed into protactinium. It remained unsolved until the mother isotope, uranium-235, was discovered in 1929.
Otto Hahn | Discovery of protactinium
Fermi arrived in New York City on 2 January 1939. He was immediately offered positions at five universities, and accepted one at Columbia University, where he had already given summer lectures in 1936. He received the news that in December 1938, the German chemists Otto Hahn and Fritz Strassmann had detected the element barium after bombarding uranium with neutrons, which Lise Meitner and her nephew Otto Frisch correctly interpreted as the result of nuclear fission. Frisch confirmed this experimentally on 13 January 1939. The news of Meitner and Frisch's interpretation of Hahn and Strassmann's discovery crossed the Atlantic with Niels Bohr, who was to lecture at Princeton University.
Enrico Fermi | Manhattan Project
From 1933 to 1935, he was a teaching assistant at the Johann Wolfgang Goethe University Frankfurt am Main. From 1936 to 1937, he was a teaching assistant to Werner Heisenberg at the University of Leipzig. From 1937 to 1942, as successor to Max Delbrück, Flügge was an assistant to Otto Hahn at the "Kaiser-Wilhelm Institut für Chemie" (KWIC, after World War II reorganized and renamed the Max Planck Institute for Chemistry), in Berlin-Dahlem. In 1938, Flügge completed his Habilitation at the "Technische Hochschule München" (today, the Technical University of Munich). In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to "Naturwissenschaften" reporting they had detected the element barium after bombarding uranium with neutrons; simultaneously, they communicated these results to Lise Meitner, who had in July of that year fled to The Netherlands and then went to Sweden.
Siegfried Flügge | Career
Hans Hahne was born the son of a sugar manufacturer. He attended school in Artern and after 1885 in Berlin and Magdeburg, where he graduated in 1894 from the "Domgymnasium". At the Universities of Jena, Munich, and Leipzig, he studied natural sciences and medicine and received his MD in 1899. This was followed by specialist training in Bern, Berlin, and Leipzig. In 1902 Hahne settled in Magdeburg as an internist and neurologist, but closed his practice in 1905 to devote himself to prehistory and early history . In the years 1905-1907 Hahne studied prehistory under Gustaf Kossinna at the University of Berlin.
Hans Hahne (archaeologist) | Life
Source: Society of German Chemists
Otto Hahn Prize | Recipients: Otto Hahn Prize
In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to "Naturwissenschaften" reporting they had detected the element barium after bombarding uranium with neutrons. They communicated these results to Lise Meitner, who, with her nephew Otto Frisch, correctly interpreted these results as being the result of nuclear fission. Frisch then confirmed this experimentally on January 13, 1939. Even before it was published, Meitner’s and Frisch’s interpretation of the work of Hahn and Strassmann crossed the Atlantic Ocean with Niels Bohr, who was to lecture at Princeton University. Isidor Isaac Rabi and Willis Lamb, two Columbia University physicists working at Princeton, heard the news and carried it back to Columbia.
John R. Dunning | Manhattan Project
From 1937, Starke was an assistant to Otto Hahn at the "Kaiser-Wilhelm-Institut für Chemie" (KWIC, Kaiser Wilhelm Institute for Chemistry; today, the "Max Planck Institut für Chemie - Otto Hahn Institut"), in Berlin-Dahlem. In 1940, scientists in both Germany and America were working on transuranic elements. Starke discovered the transuranic element neptunium (atomic number 93), independently from the American team of Edwin McMillan and Philip Abelson. The war and his move to Munich in 1941 delayed publication of his results until 1942. In 1941, Starke transferred to the "Institut für physikalische Chemie" under Klaus Clusius at the "Ludwig-Maximilians-Universität München". Shortly after the move, Starke was drafted into military service.
Kurt Starke | Career
Otto Sackur (28 September 1880 in Breslau, Germany – 17 December 1914 in Berlin, Germany) was a German physical chemist. He is known for the development of the Sackur–Tetrode equation, which he developed independently of Hugo Tetrode. His and Tetrode's names are also combined to name the Sackur–Tetrode constant derived using the equation. Sackur studied at the University of Breslau, receiving his doctorate there in 1901. He then worked in London before joining the Fritz Haber Institute in Berlin. He died in an explosion after mixing two chemicals.
Otto Sackur | Introduction
Hahn purchased two milligrams of radium from Friedrich Oskar Giesel, the discoverer of emanium (radon), for 100 marks a milligram, and obtained thorium for free from Otto Knöfler, whose Berlin firm was a major producer of thorium products. In the space of a few months Hahn discovered mesothorium I (radium-228), mesothorium II (actinium-228), and – independently from Boltwood – the mother substance of radium, ionium (later identified as thorium-230). In subsequent years, mesothorium I assumed great importance because, like radium-226 (discovered by Pierre and Marie Curie), it was ideally suited for use in medical radiation treatment, but cost only half as much to manufacture.
Otto Hahn | Discovery of mesothorium I
While at Vanderbilt, Slack maintained ties with his "alma mater" Columbia University. In December 1938, the German chemists Otto Hahn and Fritz Strassmann sent a manuscript to "Naturwissenschaften" reporting they had detected the element barium after bombarding uranium with neutrons; they communicated these results to Lise Meitner. Meitner, and her nephew Otto Robert Frisch, who correctly interpreted these results as being nuclear fission. Frisch confirmed this experimentally on 13 January 1939. In 1944, Hahn received the Nobel Prize for Chemistry for the discovery of nuclear fission. Some historians have documented the history of the discovery of nuclear fission and believe Meitner should have been awarded the Nobel Prize with Hahn.
Francis G. Slack | Career
Fajans and Otto Hahn were the discoverers of the formula that defined the conditions of the precipitation and absorption of radioactive substances. It is very significant in the context of radiochemical methods of separating and cleaning radioactive substances found in the smallest number. In 1919, Fajans started researching the structure of particle and crystal by the thermochemical and refractometrical methods. The co-relation of Born, Fajans and Haber is one of the basic thermochemical rule. On the basis of his research data Fajans formulated the essential conclusions concerning chemical bonding strength and deformation of ions and particles, such as heat of ion hydration, refraction measurements and the heat of sublimation.
Kazimierz Fajans | Scientific work