Otto Hahn
Discovery Nuclear fission
Source: Encyclopaedia
Britannica
Written By: Robert Spence
Otto Hahn, (born March 8, 1879, Frankfurt am Main, Ger.—died July 28, 1968, Göttingen, W.Ger.), German chemist who, with the
radiochemist Fritz Strassmann, is credited with the discovery of nuclear fission. He was awarded the Nobel Prize for Chemistry in 1944 and shared the Enrico
Fermi Award in 1966 with Strassmann and Lise Meitner.
Early life
Hahn was the son of a
glazier. Although his parents wanted him to become an architect, he eventually
decided to study chemistry at the University of Marburg. There Hahn
worked hard at chemistry, though he was inclined to absent himself from physics and mathematics lectures in favour of art
and philosophy, and he obtained his doctorate in 1901.
After a year of military service, he returned to the university as chemistry
lecture assistant, hoping to find a post in industry later on.
In 1904, he went to London,
primarily to learn English, and worked at University College with Sir William Ramsay, who was interested in radioactivity. While
working on a crude radium preparation that Ramsay had given to him to
purify, Hahn showed that a new radioactive substance, which he called
radiothorium, was present. Fired by this early success and encouraged by
Ramsay, who thought highly of him, he decided to continue with research on radioactivity rather than go into industry. With Ramsay’s
support he obtained a post at the University of
Berlin. Before
taking it up, he decided to spend several months in Montreal with Ernest Rutherford (later Lord Rutherford of Nelson) to gain
further experience with radioactivity. Shortly after returning to Germany in 1906, Hahn was joined by Lise Meitner, an Austrian-born physicist, and five years
later they moved to the new Kaiser Wilhelm Institute for Chemistry at
Berlin-Dahlen. There Hahn became head of a small but independent department of
radiochemistry.
Feeling that his future was
more secure, Hahn married Edith Junghans, the daughter of the chairman of Stettin City Council, in 1913; but World War I broke out the next year, and Hahn was posted
to a regiment. In 1915 he became a chemical-warfare specialist, serving on all
the European fronts.
After the war, Hahn and
Meitner were among the first to isolate protactinium-231, an isotope of the recently discovered radioactive
element protactinium. Because nearly all the natural radioactive
elements had then been discovered, he devoted the next 12 years to studies on
the application of radioactive methods to chemical problems.
Discovery of
nuclear fission
In 1934 Hahn became keenly
interested in the work of the Italian physicist Enrico Fermi, who found that when the heaviest natural
element, uranium, is bombarded by neutrons, several
radioactive products are formed. Fermi supposed these products to be artificial
elements similar to uranium. Hahn and Meitner, assisted by the young Strassmann, obtained results that at first seemed in
accord with Fermi’s interpretation but that became increasingly difficult to
understand. Meitner fled from Germany in July 1938 to escape the persecution of
Jews by the Nazis, but Hahn and Strassmann continued the work. By the end of
1938, they obtained conclusive evidence, contrary to previous expectation, that
one of the products from uranium was a radioactive form of the much lighter
element barium, indicating that the uranium atom had split into two lighter atoms. Hahn sent
an account of the work to Meitner, who, in cooperation with her nephew Otto Frisch, formulated a plausible explanation of the
process, to which they gave the name nuclear fission.
The tremendous implications of this discovery were realized by
scientists before the outbreak of World War II, and a group was formed in Germany to study
possible military developments. Much to Hahn’s relief, he was allowed to
continue with his own researches. After the war, he and other German nuclear
scientists were taken to England, where he learned that he had been awarded the
Nobel Prize for 1944 and was profoundly affected by the announcement of the
explosion of the atomic bomb at Hiroshima in 1945. Although now aged 66, he was still
a vigorous man; a lifelong mountaineer, he maintained physical fitness during
the enforced stay in England by a daily run.
On his return to Germany he
was elected president of the former Kaiser Wilhelm Society (renamed the Max Planck Society for the Advancement of Science) and
became a respected public figure, a spokesman for science, and a friend of Theodor Heuss, the first president of the Federal Republic
of Germany. He campaigned against further development and testing of nuclear
weapons. Honours came to him from all sides; in 1966 he, Meitner, and
Strassmann shared the prestigious Enrico Fermi Award. This period of his life
was saddened, however, by the loss of his only son, Hanno, and his
daughter-in-law, who were killed in an automobile accident in 1960. His wife
never recovered from the shock. Hahn died in 1968, after a fall; his wife
survived him by only two weeks.
With affection,
Ruben
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