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Physicists discover new way to visualize shape changes in molecules |
| Theallineed.com |
(NC&T/UCB) The team, which includes CU-Boulder MacArthur fellow Margaret Murnane and her husband, physicist Henry Kapteyn, published their findings this week on the Web site of the Proceedings of the National Academy of Sciences. JILA is a joint institute of the National Institute of Standards and Technology and CU-Boulder.
Kapteyn explained that the new technique could someday lead to advances in pharmaceuticals, chemicals and other industries.
"This is an important step in the exploration of the molecular world," said Kapteyn. "If we can understand exactly what's going on in a chemical reaction, our chances of manipulating it in a desired way are greatly improved."
Molecules are generally viewed as the smallest particle of a chemical substance that still retains the chemical composition of the substance. Molecules are comprised of many atoms, which are the smallest particles that retain the characteristics of chemical elements. When molecules combine to form chemical compounds, their shape must change.
 | | Margaret Murnane. (Photo: U. Colorado B.) |
"Understanding how atoms move within a molecule to change that molecule's shape is therefore crucial in learning, for example, what makes chemical reactions efficient in the human body or in a chemical catalyst," Murnane said.
Previously, scientists could only gather data that inferred how atoms or molecules move during a chemical reaction. Visible lasers, X-rays or electrons were used to scatter atoms from a molecule. However, visible light cannot see individual atoms in molecules, and it is difficult to produce very short bursts of X-rays or electrons, according to Murnane.
The CU-Boulder team used the electric field from an intense laser pulse to pluck electrons away from a molecule and then slam them back into the same molecule. The highly energetic electrons scatter from the molecule and emit bright bursts of X-rays that are detected and measured.
"The brightness of the X-ray bursts is highly sensitive to the microscopic position of the atoms within a molecule," Murnane said. "This is because, although electrons are particles, they also have wave-like properties and their wavelength is comparable to distances between atoms in a molecule."
The new method shows great promise as a way of imaging energetic molecules undergoing ultrafast structural transformations, including the fundamental action of chemistry, the making and breaking of chemical bonds, according to the CU-Boulder team.
Kapteyn explained that scientists will need years of experimentation with this new technique to determine just how much can be learned about chemical reactions at the molecular level.
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©2006 All rights reserved
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| Quotes | Figures wont lie, but liars will figure.
General Charles H. Grosvenor.
He thought the formula for water was H-I-J-K-L-M-N-O (H-to-O).
He uses statistics as a drunken man uses lampposts — for support rather than illumination. — Andrew Lang.
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