Listen up! New experiment records ultrafast chemical reaction with vibrational echoes

Aug 31, 2010
The molecules shown here in yellow are first-hand observers to an ultrafast chemical reaction. As the reaction proceeds, the vibrational frequencies of the yellow molecules change. By "listening" to changes in these vibrational frequencies, researchers Kevin Kubarych and Carlos Baiz could observe the chemical reaction underway. The rainbow colors indicate how the "notes" of the yellow molecules change in response to the reaction. Credit: Kevin Kubarych and Carlos Baiz

(PhysOrg.com) -- To watch a magician transform a vase of flowers into a rabbit, it's best to have a front-row seat. Likewise, for chemical transformations in solution, the best view belongs to the molecular spectators closest to the action.

Those special molecules comprise the "first solvation shell," and although it has been known for decades that they can sense and dictate the fate of nearly every chemical reaction, it has been virtually impossible to watch them respond. University of Michigan researchers Kevin Kubarych and Carlos Baiz, however, recently achieved the feat. Their work was published online Aug. 25 in the .

Until now, observing the solvent shell in action has been difficult for several reasons. First, fundamental steps in chemical reactions are exceedingly fast. To "film" a chemical reaction requires a camera with a "" of femtoseconds (one is the time it takes light to travel the length of a bacterium—about half a micrometer, or one hundredth the width of a human hair).

Second, a solution contains many solvent molecules, but only a few are privileged to be in the first solvation shell and participate in the reaction. Finally, most spectroscopic probes of liquids are not chemically specific, meaning they can't identify the particular molecular species they are monitoring.

To sum up, watching the first solvation shell respond to a chemical reaction requires a combination of ultrafast time resolution and the ability to initiate the reaction and track the solvent shell's response. It is this combination that Kubarych, an assistant professor of chemistry, and graduate student Baiz have achieved.

The key breakthrough was to realize that move during chemical reactions and that when the nearest solvent molecules sense the electron redistribution, their vibrational frequencies change. Much as the strings on a musical instrument are intimately connected to the wooden neck and body, the solvent shell and the reacting molecule are tightly coupled and difficult to disentangle. Indeed, the very act of holding an instrument may cause it to warp or heat up and, in principle, these changes affect the frequencies of vibration of the strings. Similarly, the new approach to reaction dynamics introduced by Kubarych's lab essentially "listens" to the very fastest events in by noting the changing resonance frequencies of the surrounding molecules.

"This level of detailed information on the complex environments common in chemical transformations is unique," Kubarych said, "and promises to offer remarkable insight into the understanding of natural and artificial charge transfer reactions—processes that are of fundamental importance in contexts ranging from cellular respiration to solar energy conversion."

Explore further: Devices designed to identify pathogens in food

More information: pubs.acs.org/journal/jacsat

Related Stories

Water: the Solvent of Choice

May 16, 2005

Miscibility not required: chemical reactions "on water" faster than in organic solvents We all know what it means to put something "on ice", but what is a chemical reaction "on water"? This new expression has been coined by a ...

Researchers shed new light on catalyzed reactions

Nov 19, 2008

Rice University scientists on the hunt for a better way to clean up the stubborn pollutant TCE have created a method that lets them watch molecules break down on the surface of a catalyst as individual chemical bonds are ...

Recommended for you

Devices designed to identify pathogens in food

May 27, 2015

Researchers at the National Polytechnic Institute (IPN) in Mexico have developed a technology capable of identifying pathogens in food and beverages. This technique could work in the restaurant industry as ...

Biosensor may improve clinical diagnosis of influenza A

May 27, 2015

Sensors based on special sound waves known as surface acoustic waves (SAWs) are capable of detecting tiny amounts of antigens of Influenza A viruses. Developed by A*STAR researchers, the biosensors have the ...

New chip makes testing for antibiotic-resistant bacteria faster, easier

May 26, 2015

We live in fear of 'superbugs': infectious bacteria that don't respond to treatment by antibiotics, and can turn a routine hospital stay into a nightmare. A 2015 Health Canada report estimates that superbugs have already cost Canadians $1 billion, and are a "serious and growing issue." Each year two million people in the U.S. contract antibiotic-re ...

Use your smartphone for biosensing

May 26, 2015

An Australian research team has shown that smartphones can be reconfigured as cost-effective, portable bioanalytical devices, with details reported in the latest edition of the Open Access Journal 'Sensors'.

Faster, portable microbial analysis in the field

May 25, 2015

Until recently, it took hours – sometimes days – to analyze biological samples after they were frozen in the field and brought back to the laboratory. But now there is a faster, cheaper and smaller way ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.