Darleane Hoffman, Harold Johnston to Receive National Medal of Science

May 2, 1997

Nuclear chemist Darleane Hoffman and atmospheric chemist Harold Johnston, both researchers at Berkeley Lab and professors at UC Berkeley, are among nine winners of the prestigious National Medal of Science announced April 30 by the White House and the National Science Foundation.

The two chemists will receive the medal later this year during a ceremony at the White House. The Medal of Science, which is awarded by the President, is the United States' equivalent of the Nobel Prize.

Hoffman, 70, is a faculty senior scientist in the Nuclear Science Division and a professor in the graduate school at UC Berkeley. She is internationally recognized for her studies of the chemistry of the so-called transuranic elements--chemical elements heavier than uranium that typically decay to lighter elements in seconds to milliseconds. In 1993 she was among the researchers who confirmed the existence of element 106, the heaviest element found so far and recently named seaborgium after long-time colleague and Nobel Prize winner Glenn Seaborg.

Johnston, 76, professor emeritus of chemistry at UC Berkeley and researcher in the Chemical Sciences Division at Berkeley Lab, was among the first to sound the alarm in the 1970s that human activities can harm the Earth's atmosphere. His scientific concerns about the effects of man-made chemicals on the ozone layer, heatedly attacked at the time, have been borne out by the subsequent discovery of ozone holes over the Earth's poles.

The National Medal of Science, established by Congress in 1959 and administered by the National Science Foundation, honors individuals who have made a major impact on the present state of knowledge in the fields of physical, biological, mathematical, engineering or social and behavioral sciences.

"It is important that the nation publicly repay its debt to these outstanding men and women, whose contributions to science have helped to advance human learning, fight disease and provide insight into the central questions of the nature of universe and humanity's place in it," said NSF Director Neal Lane in announcing the winners.

The other recipients of the National Medal of Science are the late Martin Schwarzschild (Princeton University); Nobel Laureate James D. Watson (Cold Spring Harbor Laboratory); William K. Estes (Harvard University); Marshall N. Rosenbluth (UC San Diego); Robert A. Weinberg (Whitehead Institute for Biomedical Research and MIT); George W. Wetherill (Carnegie Institution of Washington); and Shing-Tung Yau (Harvard University).

Before coming to Berkeley, Hoffman spent 31 years at Los Alamos National Laboratory, where she worked on nuclear chemistry and the spontaneous fission of elements such as fermium. There, she established herself as the world authority on spontaneous fission, the sudden decay of heavy nuclei into two "daughter" nuclei.

She also worked on radionuclide migration in the environment, studies relevant to the storage of radioactive waste. She continued her work on transuranics after joining the UC Berkeley faculty in 1984. Through her affiliation at Berkeley Lab she has used the 88-inch cyclotron to create rare heavy elements, often generating only a few atoms per week for study.

From its inception in 1991 until she retired last year, Hoffman directed the Glenn T. Seaborg Institute for Transactinium Science, which is devoted to elements heavier than actinium (element 89). A major emphasis is education and training in heavy element research.

She currently is involved in an international collaboration to study the chemistry of elements 104 (rutherfordium), 105 (hahnium) and 106 (seaborgium), using "atom-at-a-time" techniques that she and her colleagues developed. Her work has helped establish the chemical families to which these short-lived elements belong.

Hoffman was born in Terril, Iowa, and attended Iowa State University, where she received a Ph.D. in chemistry in 1951. She took a job as a chemist at Oak Ridge National Laboratory, and in 1953 moved to Los Alamos National Laboratory, where she remained moving to Berkeley in 1984.

She has served on many government advisory boards, including currently the NAS Board on Radioactive Waste Management. She is a fellow of the American Institute of Chemists and the American Physical Society, and a member of the Norwegian Academy of Science and Letters. She has received the Nuclear Chemistry Award and the Garvan Medal from the American Chemical Society, and in 1996 UC Berkeley's highest academic award, the Berkeley Citation.

Johnston's research concerned the chemical reactions that take place in a mixture of gases, and also how light affects these reactions. In particular he looked at oxides of nitrogen--referred to as NOx, the major constituents of smog--as well as ozone, fluorine, chlorine and various highly reactive free radicals.

His work on NOx reactions first led him to question a proposal of the late 1960s that the country build a fleet of supersonic transport planes that would fly in the stratosphere. His calculations in 1971 indicated that NOx spewed into the stratosphere from the airplanes' exhaust could reduce global ozone by 3 to 23 percent. Because this ozone protects us from the sun's damaging ultraviolet rays, this could have a deleterious effect on life on the planet.

Following publication of his findings and the associated publicity, Congress set up its first major program of stratospheric research. From this beginning came warnings about other ozone destroyers including chlorofluorocarbons, which have since been banned in the U.S. and many other countries. In 1982 the Federal Aviation Agency awarded Johnston its citation for "Service in Aviation" for his work on high altitude aircraft pollution.

In 1991 Johnston was part of a NASA team that showed that at some altitudes and in some conditions supersonic passenger aircraft could operate with little or no effect on ozone.

Johnston was elected to the National Academy of Sciences in 1965 and to the American Academy of Arts and Sciences in 1972. He also received the Tyler World Prize for Environmental Achievement in 1983 and the NAS Award for Chemistry in Service to Society in 1993. He is a member of the American Chemical Society and a fellow of the American Geophysical Union and the American Physical Society.

Johnston came to UC Berkeley in 1957 as a professor of chemistry, and served as dean of the College of Chemistry from 1966 to 1970. He retired in 1991, at which time he received the UC's academic honor, the Berkeley Citation.

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