Chemistry ETDs

Publication Date



From a sample of uranium bombarded with neutrons, Hahn and Strassmann, in 1939, separated four radioactive products which followed alkaline earth chemistry and were therefore tentatively attributed to isotope of radium. Each of these products decayed to a daughter activity which could be precipitated along with lanthanum; the daughter activities were then assumed to be isotopes of actinium. Subsequently, by accepted methods of fractional crystallization and precipitation, the "radium" and "actinium" isotopes were identified unequivocally as isotopes of barium and lanthanum, respectively. Within a relatively short time there were found more such radioactive products, which were identified as isotopes of elements between bromine and lanthanum. This startling result could be explained only by the assumption that the uranium nucleus, after capture of a neutron, split into two fragments of similar mass. Thus, by radiochemical methods, the phenomenon of nuclear fission was discovered. Within a year of the original discovery of Hahn and Strassmann, about fifty more radioactive fission-product nuclides had been isolated.

By 1941, extensive physical and chemical studies had revealed the nature and implications of the fission phenomenon; during the period 1941-1945 fission radiochemistry was pursued intensively under wartime secrecy, and when in 1946 the results of this work were finally released and published, the number of known fission products had been extended to over 160.

Project Sponsors

Los Alamos National Laboratory



Document Type


Degree Name


Level of Degree


Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Milton Kahn

Second Committee Member

J. D. Knight

Third Committee Member

John Francis Suttle

Fourth Committee Member

Jesse LeRoy Riebsomer

Fifth Committee Member

Ernest Lynne Martin

Sixth Committee Member

Carleton Eugene Buell