Wahl, professor who discovered plutonium; 89

Arthur G. Wahl, Ph.D., the Henry V. Farr Professor of Radiochemistry from 1952 until his retirement in 1983, died Monday, March 6, 2006, of Parkinson’s disease and pneumonia in Santa Fe, N.M. He was 89.

Wahl was famous for proving the existence of a radioactive isotope, element 94 on the periodic table, that had been postulated but never isolated. He discovered what would come to be called plutonium as a team member of nuclear chemists at the University of California, Berkeley, in 1941.

Arthur Wahl
Arthur Wahl

It became clear to the scientists working on the element that the isotope of plutonium with the mass number 239 was fissionable and could be used to make a weapon.

In early 1943, J. Robert Oppenheimer, the director of the secret project being organized at Los Alamos, asked Glenn T. Seaborg, who led Wahl’s group, to come to “The Hill,” with his Berkeley team.

Wahl was a group leader in the Nuclear Chemistry Division from 1943-46. When they arrived, they found that the goal of the scientists at Los Alamos was to use plutonium that was extremely pure, thus reducing the possibility of a spontaneous fission. At Los Alamos, Wahl developed a plutonium purification method that is still in use today.

In 1946, Washington University recruited one of the team members, Joseph Kennedy. Kennedy accepted the offer with the condition that he could bring the Los Alamos nuclear chemistry team with him.

Kennedy took Lindsay Helmholz, David Lipkin, Herbert Potratz, Wahl and Samuel Weissman. Kennedy was chair of the Department of Chemistry in Arts & Sciences for the next 10 years until his death from cancer at age 41.

The six scientists were honored at a portrait unveiling at WUSTL in September. Weissman is the only original member of the Los Alamos chemists still living and working at the University.

Wahl earned a bachelor’s degree in radiochemistry in 1930 from Iowa State University and a doctorate in 1942 from the University of California, Berkeley.

He is survived by his wife, Mary, and daughter, Nancy Miegel.

A fund has been established in his name for the WUSTL chemistry department. Contributions may be sent to The Arthur Wahl Endowment Fund, Development Services, Washington University, Box 1082, St. Louis, MO 63130.

A memorial gathering is scheduled for 1-3 p.m. May 28 in the Arts & Sciences Laboratory Science Building, Room 250.