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Press Release 06-056

Frictionless Motion Observed in Water

Discovery could have fundamental implications for chemistry

Each rotating cyanide molecule throws back the surrounding water molecules.


Each rotating cyanide molecule throws back the surrounding water molecules.
Credit and Larger Version


April 7, 2006

By using ultra-short laser pulses to spin a cyanide molecule like a propeller, chemists at the University of Southern California and Brown University have achieved the first known demonstration of near-frictionless motion in water. Although the discovery has no immediate practical use, says USC chemist Stephen Bradforth, "it impacts how we think about the vast majority of chemical reactions"--90 percent of which take place in liquid solutions.

Indeed, the technique gives chemists a potential new tool to influence how a reaction progresses, as one way to do that is to isolate an interacting molecule from its surroundings.

In experiments they describe in a recent issue of the journal Science, the chemists start with a water sample containing cyanide molecules, each of which is basically a molecular stick with a carbon atom at one end and a nitrogen atom at the other. Then they spin the sticks to with a laser.

Within the first quarter-turn, each rotating cyanide molecule creates a shock wave that throws back the surrounding water molecules. (Bradforth, who is part of the study team, likens the phenomenon to a passenger swinging a suitcase in a crowded airport terminal, minus the real-life bruises and hurt feelings.) Inside the resulting bubble, the molecule will then continue whirling for a time with essentially no friction.

Besides Bradforth, authors of the report included Brown University chemist Richard Stratt, graduate students Amy Moskun and Askat Jailaubekov from USC, and Guohua Tao from Brown.

Primary funding for this work came from the National Science Foundation, with additional support from the David and Lucile Packard Foundation.

For more information, see the USC news release.

-NSF-

Media Contacts
M. Mitchell Waldrop, NSF, (703) 292-7752, mwaldrop@nsf.gov
Wendy Lawton, Brown University, (401) 863-1862, wendy_lawton@brown.edu
Carl Marziali, University of Southern California, (213) 219-6347, marziali@usc.edu

Related Websites
The USC news release: http://www.usc.edu/uscnews/stories/12246.html
Brown University news release: http://www.brown.edu/Administration/News_Bureau/2005-06/05-101.html

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2016, its budget is $7.5 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 48,000 competitive proposals for funding and makes about 12,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.

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