HAHN, OTTO

HAHN, OTTO (1879–1968), chemist; directed the Kaiser Wilhelm Institute for Chemistry during 1928–1944. Born in Frankfurt, he decided at an early age to become an industrial chemist. Defying his father, who wanted him to be an architect, he began studies at Marburg in 1897 and completed a doctorate in organic chemistry in 1901. To cultivate his English, Hahn obtained a position in 1904 at William Ramsay's laboratory in London. Pivotal research followed when, while working with Ramsay, he isolated an unknown radioactive substance, radiothorium. Excited by his find, he went to Montreal in 1905 to work with Ernest Rutherford, the era's radioactivity authority. At Ramsay's urging, Hahn focused on radium research and in 1906 joined the institute of the famous Berlin* chemist Emil Fischer. He was soon appointed Privatdozent in Fischer's so-called carpentry shop and began a thirty-year association in 1907 with the Austrian physicist Lise Meitner.* In their joint research into radioactivity, Hahn focused on chemistry while Meitner handled physics. When the Kaiser Wilhelm Society* (KWG) opened its Institut fu¨r Chemie in 1912, Hahn, who became head of the radioactivity department, invited Meitner to join his laboratory. During World War I, as an officer in the gas-warfare corps, he served under the supervision of Fritz Haber.* Despite heavy involvement in weapons development, he and Meitner isolated a new element, protactinium, in 1918. By the 1920s most of the natural radioactive elements were known and prospects for research were narrowing. After brief work with tracer techniques, Hahn entered the new arena of nuclear chemistry. Shortly before Hitler's* seizure of power, he joined Meitner and Fritz Strassmann, an analytical chemist, in cataloging the properties of transuranium elements. Neither a Nazi nor a participant in Germany's later bomb project, he was identified by the Gestapo as part of the ‘‘Einstein clique.'' In mid-1938 Meitner, of Jewish ancestry, was forced by the Anschluss to flee Germany. When Hahn and Strassmann were later baffled by an experiment in which uranium was transmuted into radioactive barium, Meitner concluded that her erstwhile colleagues had produced fission of the uranium nucleus. Without learning of it until after the war, Hahn was awarded the 1944 Nobel Prize in chemistry. Although he was interned in England in 1945, he returned to Berlin in 1946 as president of the Max Planck Society, the renamed KWG. The rest of his life was given to restoring German science and warning against the improper use of nuclear power.