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The molecular features that influence
the rate of chemical reactions were
poorly understood until the mid-1960s,
when Dudley Herschbach and his postdoctoral
student Yuan T. Lee began a series
of experiments at Harvard University.
With funding from the Office of Science
and predecessor agencies, they explained
in detail how chemical reactions take
place, and solved the problem of how
to observe the random directions and
velocities of molecules in a gas or
a liquid. They developed an apparatus
in which crossed molecular beams were
used to vary the velocities and approach
angles of reacting molecules. With
this tool, the scientists discovered
and studied long-lived complexes of
reactants formed before a reaction
was completed, and described theoretically
their formation and decay. They also
examined the velocities of products,
rotational energies, and internal
vibration energies. In this way, they
could map out all the details of a
chemical reaction and explain the
effects of temperature and pressure.
Initially, these studies focused on
reactions between alkali atoms and
other molecules; Lee later adapted
the crossed molecular beam method
for general reactions. The 1986 Nobel
Prize in Chemistry was awarded jointly
to Herschbach, Lee, and a third scientist.
Scientific Impact:
This work contributed significantly
to the modern knowledge base for atmospheric
and combustion chemistry. These scientists
helped establish reaction dynamics
as a discrete field of research, and
their crossed molecular beam approach
is among the most important contributions
to this field.
Social Impact: These
studies contributed to improvements
in industrial production efficiency
and assisted in the design of new
products to be more useful, durable,
and conserving of natural resources.
This work also contributed to the
development of predictive theories
and models used to design and manufacture
new products ranging from plastics
to pharmaceuticals.
Reference: http://www.nobel.se/chemistry/laureates/1986/press.html
http://www.nobel.se/chemistry/articles/decades.htm
URL:
http://www.sc.doe.gov/production/bes/chm/Programs/programs.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 |
