Technique lets scientists view step-by-step breakdown of water pollutant
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 formed and broken.
"We can see the vibrations of the bonds between the atoms of our molecules,” said researcher Michael Wong. "By watching the way these vibrations change frequency and intensity with time, we can watch how molecules transform into other molecules step-by-step."
The research is available online in the Journal of the American Chemical Society.
This chemical sensing technique relies on nanoparticles consisting of gold and silica called nanoshells, invented 10 years ago at Rice by nanophotonics pioneer Naomi Halas. Nanoshells are about 20 times smaller than a red blood cell, and they can amplify light waves and focus them so tightly that scientists can use them to detect just a few molecules of a target chemical. Building catalysts directly on the surface of the nanoparticles themselves allows researchers to use the nanosensing capabilities of nanoshells to directly follow chemical reactions on the catalyst using light.
"Nanoshells are among the world's most effective chemical sensors, and this study reveals another area where they are uniquely valuable," said Halas, the Stanley C. Moore Professor in Electrical and Computer Engineering, professor of chemistry and director of Rice's Laboratory for Nanophotonics. "We are aware of no other method that provides this level of detail about metal-catalyzed chemical reactions that run in water. Given the overwhelming interest in biofuels processing and other water-based reactions, we expect this to be a very useful tool in understanding these chemistries in more detail."
The research is supported by the National Science Foundation, the Welch Foundation and the Gulf Coast Consortia's Keck Center for Interdisciplinary Bioscience Training.
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