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
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
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
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.