
Crystalline Structure of Carbon Dioxide Seen for the First TimeBy Hank Becker February 23, 1998For the first time, scientists are able to see the crystalline structure of
carbon dioxide--a view that could help them learn how the crystals cause the
greenhouse effect. According to William Wergin and colleagues with the
Agricultural Research Service, carbon
dioxide crystals are as small as 1/200,000 of an inch. The crystals generally
appear as eight-sided structures called octahedrons, the scientists say. Carbon dioxide ranks high--along with nitrous oxide and methane--as a
greenhouse gas that contributes to global warming as it increases in
concentration in the atmosphere. Scientists say knowing the crystalline
structure may give them clues to the capacity of carbon dioxide gas to absorb
and re-radiate energy, which is the behavior of greenhouse gas that makes it so
troubling. Plants take up carbon dioxide through photosynthesis. When they are
harvested, the crop residue is incorporated into soil and becomes organic
carbon. This gives farmers a chance to reduce atmospheric carbon dioxide by
improving their management of agricultural systems to increase soil organic
carbon. The spinoff benefits from increased soil organic carbon are reduced
soil erosion and improved soil tilth- -an indicator of soil health. No one has ever before seen the structure of carbon dioxide crystals because
the crystals evaporate at temperatures higher than minus 210 degrees F. But at
ARS' Nematology
Laboratory in Beltsville, Md., the scientists used a special scanning
electron microscope (SEM) to view the crystals. At one point in the SEM viewing
process, the material under observation is cooled to minus 320 degrees F, making
it possible to observe the structure of the crystals of solid carbon dioxide. Scientific contact: William P. Wergin, ARS
Nematology Laboratory,
Beltsville Agricultural Research Center,
Beltsville, Md., phone (301) 504-9027, fax (301) 504-8923,
[email protected]. U.S. Department of Agriculture | |