Featured Research

from universities, journals, and other organizations

Frictionless Motion Observed In Water -- Discovery Has Fundamental Implications For Chemistry

Date:
April 3, 2006
Source:
University of Southern California
Summary:
A molecule spinning in a liquid can create a friction-free bubble for itself, researchers report in Science. The finding violates established theory and may reshape basic models of chemical reactions.

Free rotation can occur in gases, where molecules are far apart, researchers said.
Credit: Image courtesy of University of Southern California

Researchers at the University of Southern California and Brown University say they have achieved near-frictionless motion in water by using lasers to spin a molecule like a propeller.

Related Articles


Free rotation can occur in gases, where molecules are far apart. This is the first known demonstration of friction turning off in a room temperature liquid, the authors report in the Mar. 31 issue of Science.

Graduate student Amy Moskun and her advisor Stephen Bradforth, associate professor of chemistry in the USC College of Letters, Arts and Sciences, used ultra-short, high-energy laser pulses to spin a CN "diatomic" -- a simple molecular stick with a carbon at one end and a nitrogen at the other.

Within the first quarter-turn the molecular stick creates a shock wave, throwing back the water molecules that had been crowding it.

"If you give it enough spin, it pushes all the guys around it away," said Bradforth, "and it builds itself a little bubble. It's destroyed the friction in the liquid around it by completely reshaping its environment."

Bradforth likened the phenomenon to a passenger swinging a suitcase around in a crowded airport terminal, minus the real-life bruises and hurt feelings.

As with the airport analogy, after some time -- about 10 complete rotations of the CN molecule -- the shock dissipates and the water molecules rush back in.

Even so, said Bradforth, the length of friction-free spinning was far greater than expected.

"Everyone's prediction was that it wouldn't even complete a few degrees of free rotation," he said.

The discovery has no immediate practical use, but since 90 percent of reactions take place in liquid solutions, Bradforth said his group's study "impacts how we think about the vast majority of chemical reactions."

In chemistry, friction is a useful phenomenon that transfers energy between molecules and allows reactions to proceed. But what if a reaction needs to be stopped or delayed? Chemists have long sought to manipulate reactions, which usually yield useless byproducts along with the desired compound.

The Science paper provides a potential new tool, since one way to influence the progress of a reaction is to isolate a molecule from its surroundings.

"Most people thought this was hopeless in a liquid," Bradforth said.

It took the researchers more than a year to grasp the significance of their work. After Moskun and Bradforth figured out how to spin up CN molecules and to observe the rotation with a strobe-like apparatus, they sent their data to Richard Stratt, professor of chemistry at Brown University.

Stratt's group of theoretical chemists showed that the data represents a violation of linear response theory, a key model for liquid behavior that states the effects of friction and molecular energy are scalable. Under the theory, the rapidly spinning CN diatomic should not have caused a fundamental change in its environment.

"People have seen linear response theory fail in simulations before," Stratt wrote in a summary for the researchers' funding agency, the National Science Foundation. "I believe these studies represent the first time anyone has ever seen that a particular, well-defined, molecular event was responsible for suddenly turning off a liquid's linear response behavior."

The USC group then verified their collaborators' interpretation with a new round of experiments.

Said Bradforth: "The theory fails in this case, and we can see why it fails."

The theory's failure may be chemistry's gain.

Bradforth and Stratt were co-authors on the Science paper, along with graduate students Moskun and Askat Jailaubekov from USC, and Guohua Tao from Brown.

Additional funding for Bradforth's group came from the David and Lucile Packard Foundation.



Story Source:

The above story is based on materials provided by University of Southern California. Note: Materials may be edited for content and length.


Cite This Page:

University of Southern California. "Frictionless Motion Observed In Water -- Discovery Has Fundamental Implications For Chemistry." ScienceDaily. ScienceDaily, 3 April 2006. <www.sciencedaily.com/releases/2006/04/060401110040.htm>.
University of Southern California. (2006, April 3). Frictionless Motion Observed In Water -- Discovery Has Fundamental Implications For Chemistry. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2006/04/060401110040.htm
University of Southern California. "Frictionless Motion Observed In Water -- Discovery Has Fundamental Implications For Chemistry." ScienceDaily. www.sciencedaily.com/releases/2006/04/060401110040.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins