50th Anniversary: Death of Otto Hahn

50th Anniversary: Death of Otto Hahn

Author: ChemViews Magazine

Otto Emil Hahn was born in Frankfurt am Main, Germany, on March 8, 1879. He studied chemistry at the Universities of Marburg and Munich, both Germany, under Theodor Zincke and Adolf von Baeyer, respectively. He received his Ph.D. in organic chemistry from the University of Marburg in 1901.

In 1904, Hahn joined University College London, UK, to work under Sir William Ramsay, the discoverer of the noble gases. Here, he started to work on radiochemistry, a field in which he was to have an enormous influence. He is sometimes referred to as the “father of nuclear chemistry”. In 1905, Hahn discovered a new isotope of thorium, which he first thought to be a new radioactive element. In fact, the term “isotope” had not been coined yet, it was first suggested in 1913 by Frederick Soddy. Ramsay recommended Hahn to Ernest Rutherford at McGill University, Montreal, Canada, who Hahn joined in 1905 and 1906. There, he discovered other new radioactive isotopes.

Hahn returned to Germany in 1906 to work with Emil Fischer at the University of Berlin, Germany. He completed his habilitation there in 1907 and, thus, qualified as lecturer. The same year, Lise Meitner transferred to Berlin from Vienna, Austria, and she and Hahn started their decades-long collaboration. Hahn was appointed Professor in Berlin in 1910. In 1912, he was chosen lead the radiochemistry department of the newly founded Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem. Hahn was the last President of the Kaiser Wilhelm Society during 1946 and the first President of its successor, the Max Planck Society, serving from 1948 to 1960.

During World War I, Hahn served in the German army. He met with Fritz Haber and worked on the preparation of the first uses of toxic gases as chemical weapons, scouting attack sites and working on testing the weapons and gas masks. Hahn resumed research in Berlin after the war. In 1917 and 1918, Hahn and Meitner worked together on the isolation of a new isotope of the radioactive element protactinium, 231Pa. Kasimir Fajans and Oswald Helmuth Göhring had discovered another isotope of the element in 1913.

In the 1930s, Hahn worked on the bombardment of uranium with neutrons together with Meitner and his student Fritz Strassmann. It was thought that transuranium elements could be prepared by this method. Meitner, who was born into a Jewish family, fled from the national socialist regime to Sweden via The Netherlands in July of 1938. Hahn supported her and gave her an inherited diamond ring to be used as a possible bribe at the border. Hahn continued to oppose the persecution of Jewish citizens. Together with his wife, he helped to provide people in hiding with food, he refused to sign a vow of allegiance of the professors of the German universities to Adolf Hitler, and he resigned his post at the University of Berlin in 1934 in protest over the firing of his Jewish colleagues.

Hahn and Strassmann continued their research at the Kaiser Wilhelm Institute and in late 1938, they found barium in the products of their uranium bombardment experiments. This was tough to explain at first, because the idea of heavy nuclei breaking apart into smaller ones seemed far-fetched. However, further evidence for the formation of light elements during the experiments gradually convinced Hahn that nuclear fission must be taking place. Meitner and her nephew Otto Robert Frisch meanwhile worked on the theoretical interpretation of the phenomenon in Sweden. Hahn was awarded the Nobel Prize in Chemistry in 1944 “for his discovery of the fission of heavy nuclei”.

In 1945, Hahn and nine other German scientists, who the Allies suspected of knowing about the German nuclear weapon project, were captured and interned by the British. During his internment, Hahn learned of the use of atomic bombs in Hiroshima and Nagasaki and was extremely distraught by this application of his discovery of nuclear fission. The announcement of his Nobel Prize also took place during this time, as the award was presented in 1945. Hahn learned about the honor from the newspaper and was unable to attend the festivities in 1945. He was allowed to return to Germany in 1946 and was presented with his Nobel Prize later that year.

After WWII, Hahn campaigned passionately against the development, production, and use of nuclear weapons. He was nominated for the Nobel Peace Prize several times, starting in 1957. Otto Hahn died on July 28, 1968.

Otto Hahn is the answer to Guess the Chemist (79).


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