 |
|
The stratospheric layer of ozone
15 to 50 kilometers above the Earth
absorbs ultraviolet radiation, preventing
it from reaching the planet's surface.
For many years, scientists assumed
that this protective ozone would not
be affected by release into the atmosphere
of chlorofluorocarbons (CFCs), chemically
inert and nontoxic gases once common
in aerosol sprays and refrigerants.
But in fact, CFCs do threaten the
ozone layer, as explained in 1974
by F. Sherwood Rowland of the University
of California, Irvine, and Mario Molina
of the Massachusetts Institute of
Technology. Rowland was supported
by predecessors to the Office of Science
for his research in hot-atom chemistry.
Initially interested in species formed
as a result of nuclear reactions,
he extended his work to study the
photochemical formation of chlorine
atoms. Roland and Molina theorized
that CFC molecules could be split
apart by solar radiation to produce
chlorine atoms, which could catalyze
the destruction of ozone. They were
right, as underlined later by discovery
of the "ozone hole" over the Antarctic.
Rowland and Molina, together with
Paul Crutzen of the Max-Planck-Institute
for Chemistry in Germany, shared the
1995 Nobel Prize in Chemistry for
their work on the formation and decomposition
of ozone.
Scientific Impact:
Discovery of the effect of CFCs on
the ozone layer was a seminal contribution
to atmospheric chemistry.
Social Impact: Rowland
and Molina's work initially led to
restrictions on CFC releases; after
discovery of the ozone hole, an international
agreement was signed to limit the
manufacture and use of these compounds.
Thus, this research has helped mitigate
a global environmental problem with
potentially catastrophic consequences.
It will take at least 100 years for
the ozone layer to recover fully.
Reference: Molina,
M. j., and F. S. Rowland, Stratospheric
Sink for Chlorofluoromethanes: Chlorine
Catalysed Destruction of Ozone, Nature,
249, 810-814 (1974)
URL:
http://www.nobel.se/chemistry/laureates/1995/press.html
Technical Contact:
Don Freeburn, Office of Basic Energy
Sciences, 301-903-3156
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Basic Energy Sciences |
