‘Uber das Zerplatzen des Urankernes Durch Langsame Neutronen.’ [TOGETHER WITH:] HAHN, STRASSMANN and Hans GÖTTE. ‘Einiges Uber die Experimentelle Entwirrung der bei der Spaltung des Urans Auftretenden Elemente und Atomarten.’ [TOGETHER WITH:] HAHN and STRASSMANN. ‘Die Chemische Abscheidung der bei der Spaltung des Urans Entstehenden Elemente und Atomarten (Allgemeiner Teil).’ Together three issues of Abhandlungen der preussischen Akademie der Wissenschaften.
Berlin: Walter de Gruyter und Co., 1939 [1942, 1944].
First edition, offprint issues, of the three fundamental papers on nuclear fission which eventually lead to the creation of the atom bomb. “…experiments conducted in 1938 at Berlin by Hahn and Strassman [sic] were reported to Lise Meitner, an Austrian scientist who had fled to Copenhagen to escape religious persecution. She and her nephew, O. R. Frisch, working in Niels Bohr’s laboratory, found the true explanation of these phenomena. The interpolation of a neutron into the nucleus of a uranium atom caused it to divide into two parts and to release energy amounting to about 200,000,000 electron volts. This process bore such a close similarity to the division of a living cell that Frisch suggested the use of the term ‘fission’ to describe it” (PMM). “Hahn and Strassmann published this article [i.e. the 1939 paper] that started scientists down the path to the atomic bomb. Originally working with Lise Meitner who was forced to flee Nazi Germany in 1938, they had been working with uranium and bombarding samples with slow neutrons. They realized that this caused the uranium atoms to split into lighter nuclei and releasing large amounts of energy, and the implications were not lost to a world at war” (Dibner). Hahn received the 1944 Nobel Prize in Chemistry “for his discovery of the fission of heavy nuclei.”
Hahn and Meitner worked together at the Kaiser-Wilhelm Institute (KWI) of Chemistry in Berlin from 1912, discovering the new element protactinium in 1918; Strassmann joined them there in 1929 and Götte in 1935. When, after the First World War, limitations for women in the academic world were lifted, Meitner became professor at the KWI; Hahn became its director in 1928.
“In 1934 [Enrico] Fermi roused the world of radioactivity with his method of neutron bombardment and that same year reported on the possible production of transuranic elements by irradiating uranium with neutrons. The irradiation had led to radioactive substances with different half-lives such as 10s, 40s, 13min, and 90min. Fermi’s group had separated the 13-min and 90-min ‘bodies’ chemically from uranium and had shown that they were not isotopes of elements, which are located only a few places below uranium in the Periodic Table … they assumed that the uranium nucleus with the extra neutron transformed, via beta decay, into a nucleus of an element with the number 93 in the Periodic Table. That could still be unstable and transit, by another beta decay, into a nucleus of element 94.
“The idea of more than 92 elements was, of course, contested. Ida Noddack, a renowned chemist and co-discoverer of the element rhenium, pointed out that all known elements had to be excluded before new ones were proposed. This very sound advice was not taken. Nuclear physicists saw no possibility for a nucleus to fragment into large pieces. Nothing more drastic than alpha decay had ever been observed. Another way out was also proposed: in spite of Fermi’s interpretation, his 13-min body might be an isotope of protactinium, element number 91. Here Hahn and [Lisa] Meitner came in. After all, they were discoverers of protactinium and knew the properties of this element. They were able to show that the activity in question was not due to protactinium and became convinced that transuranic elements had been produced. They began intensive work in this new field, from 1935 onwards together with Strassmann … Quite a number of substances with different half-lives and different chemical properties were found in uranium irradiated with neutrons. A detailed scheme for their production was proposed, which implied the creation and subsequent decay of four, possibly five, transuranic elements. It was not seriously challenged by other groups working in the field.
“When Austria was annexed in 1938, Lise Meitner became a German citizen and, because of her Jewish descent, was in acute danger. Helped by Hahn and other colleagues, she fled via Holland and Denmark to Sweden, where she could work in the Physical Institute of the Academy of Sciences in Stockholm.
“Hahn and Strassmann continued alone. The decay products of the apparent transuranic elements seemed to contain three substances, which underwent beta decays of different half-lives and were chemically very similar to barium. They were taken to be isomeric nuclei of the isotope Ra231 of radium. Radium is an alkaline-earth metal as is barium and is located below barium in the second column of the Periodic Table, hence the similarity. Hahn and Strassmann tried to isolate the radium. Since only minute quantities could have been produced, a precipitation with barium as carrier from a solution was performed; the barium was to carry along the chemically similar radium. The precipitate then only contained barium and radium, which were to be separated in the next step. As mentioned above, Hahn was well versed in the method of separation, fractional crystallization, originally introduced by Marie Curie. But although they tried hard and checked and rechecked their method, Hahn and Strassmann were unable to separate any radium by chemical means. In their first paper they still conclude rather cautiously: ‘We come to the conclusion: Our ‘radium isotopes’ have the properties of barium; as chemists we should rather say the new bodies are not radium but barium. [. . . ] As ‘nuclear chemists’, in a certain sense close to nuclear physics, we cannot yet decide ourselves to perform this step contradicting all previous experience of nuclear physics. A series of strange coincidences might still have faked our results.’
“Hahn had kept Meitner informed by letter about the work and he mailed her a copy of the manuscript of the paper on 21 December 1938, the same day it was submitted to Die Naturwissenschaften. The manuscript reached her in a small town near Gothenburg, where she had gone to visit Swedish friends over Christmas and where she had also invited her nephew Otto Frisch. We have already met him as collaborator of Stern in Hamburg. He, too, had been forced to leave Germany and at that time was working in Bohr’s institute in Copenhagen. Meitner showed him Hahn’s letter and the manuscript and dismissed the possibility of mistake: ‘Hahn was too good a chemist for that.’ The two began to look for an explanation. The nucleus could not just been cracked like a nut. In fact there was evidence that it behaved rather like a droplet. Now, a droplet might divide into two smaller ones by contracting in one direction, then elongating, and so on, until it finally would split up. The uranium nucleus might need little extra energy to do so, because its many protons provided a repulsive electrical force counteracting the attractive nuclear force between all nucleons, protons as well as neutrons. This extra energy could be provided by a single neutron. Meitner calculated that the energy of 200 MeV would be released in a single process, an energy equivalent to one-fifth of the rest mass of a proton.
“After a few days, Frisch returned to Copenhagen and told Bohr, who was enthusiastic: ‘Oh what idiots we have all been! Oh but this is wonderful! Have you and Lise Meitner written a paper about it?’ Frisch told him that there would soon be a paper and asked Bohr, who was about to travel to the United States to participate in a conference, not to discuss the matter before it would appear in print … this promise could not be kept and Bohr’s reports triggered intense activities which led to the first nuclear reactor in less than four years …
“For the next few years, Hahn and Strassmann continued to identify radioactive isotopes produced in uranium fission. By spring of 1945, they had found a total of about 100 isotopes from 25 different elements … In 1945 Hahn was awarded the Nobel Prize in Chemistry for the year 1944 … In 1966 Meitner, Hahn, and Strassmann were the first non-US citizens to be given the Enrico-Fermi Award by the American president” (Harvest of a Century, pp. 264-7).
“Hahn was little concerned with the energy released in fission and played no part in the German atomic bomb and reactor project during World War II. Instead, he devoted most of his efforts to the study of fission fragments. When the chemical institute, of which he had become director in 1928, was destroyed in an air raid, he moved his usable equipment to southern Germany and resumed work there. With several other nuclear physicists and chemists he was arrested in the spring of 1945 by Allied troops and interned for over half a year in England. There, to his profound dismay, he heard of the application of his discovery when nuclear weapons were detonated over Hiroshima and Nagasaki. He learned also of the award to him of the 1944 Nobel Prize in chemistry, and he received a request to become president of the Kaiser Wilhelm Gesellschaft” (DSB - Hahn).
The first offered paper, “containing the first comprehensive account of the phenomenon [i.e., fission]” (Norman) was followed by the two papers published during the Second World War which describe experiments to identify the fission fragments.
Dibner, Heralds of Science, 168; Norman 963 (first paper only); PMM 422. Segré, X-Rays to Quarks, pp. 206-7. DSB VI, p. 14 for Hahn and DSB XVIII, p. 880 for Strassmann.
4to, pp. 20; 30; 14. Original printed wrappers (green, orange and green, respectively), some very light sunning to margins, spine strip of first paper with closed tear to lower part of spine strip. In all a very fine set in its original state.