HAHN, OTTO

Ci-dessous un extrait traitant le sujet : HAHN, OTTO. Ce document contient 1 mots soit pages. Pour le télécharger en entier, envoyez-nous un de vos documents grâce à notre système gratuit d’échange de ressources numériques. Cette aide totalement rédigée en format PDF sera utile aux lycéens ou étudiants ayant un devoir à réaliser ou une leçon à approfondir en: Echange.

HAHN, OTTO (1879–1968), chemist; directed the Kaiser Wilhelm Institutefor Chemistry during 1928–1944. Born in Frankfurt, he decided at an early ageto become an industrial chemist. Defying his father, who wanted him to be anarchitect, he began studies at Marburg in 1897 and completed a doctorate inorganic chemistry in 1901.To cultivate his English, Hahn obtained a position in 1904 at William Ramsay'slaboratory in London. Pivotal research followed when, while working withRamsay, he isolated an unknown radioactive substance, radiothorium. Excitedby his find, he went to Montreal in 1905 to work with Ernest Rutherford, theera's radioactivity authority. At Ramsay's urging, Hahn focused on radium researchand in 1906 joined the institute of the famous Berlin* chemist EmilFischer. He was soon appointed Privatdozent in Fischer's so-called carpentryshop and began a thirty-year association in 1907 with the Austrian physicistLise Meitner.* In their joint research into radioactivity, Hahn focused on chemistrywhile Meitner handled physics. When the Kaiser Wilhelm Society* (KWG)opened its Institut fu¨r Chemie in 1912, Hahn, who became head of the radioactivitydepartment, invited Meitner to join his laboratory. During World WarI, as an officer in the gas-warfare corps, he served under the supervision of FritzHaber.* Despite heavy involvement in weapons development, he and Meitnerisolated a new element, protactinium, in 1918.By the 1920s most of the natural radioactive elements were known and prospectsfor research were narrowing. After brief work with tracer techniques, Hahnentered the new arena of nuclear chemistry. Shortly before Hitler's* seizure ofpower, he joined Meitner and Fritz Strassmann, an analytical chemist, in catalogingthe properties of transuranium elements. Neither a Nazi nor a participantin Germany's later bomb project, he was identified by the Gestapo as part ofthe ‘‘Einstein clique.'' In mid-1938 Meitner, of Jewish ancestry, was forced bythe Anschluss to flee Germany. When Hahn and Strassmann were later baffledby an experiment in which uranium was transmuted into radioactive barium,Meitner concluded that her erstwhile colleagues had produced fission of theuranium nucleus.Without learning of it until after the war, Hahn was awarded the 1944 NobelPrize in chemistry. Although he was interned in England in 1945, he returnedto 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 againstthe improper use of nuclear power.