Berkeley Lab Researchers Find Simpler Approach to Making Plasmonic Materials
Lynn Yarris
November 22, 2011
“The question of how many polyhedral nanocrystals of silver can be packed into millimeter-sized supercrystals may not be burning on many lips but the answer holds importance for one of today’s hottest new high-tech fields – plasmonics! Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) may have opened the door to a simpler approach for the fabrication of plasmonic materials by inducing polyhedral-shaped silver nanocrystals to self-assemble into three-dimensional supercrystals of the highest possible density.”
On the left are micrographs of supercrystals of silver polyderal nanocrystals and on the right the corresponding diagrams of their densest known packings for (from top-down) cubes, truncated cubes and cuboctahedra. (Image courtesy of Berkeley Lab)
Plasmonics is the phenomenon by which a beam of light is confined in ultra-cramped spaces allowing it to be manipulated into doing things a beam of light in open space cannot. This phenomenon holds great promise for superfast computers, microscopes that can see nanoscale objects with visible light, and even the creation of invisibility carpets. A major challenge for developing plasmonic technology, however, is the difficulty of fabricating metamaterials with nano-sized interfaces between noble metals and dielectrics.
Peidong Yang, a chemist with Berkeley Lab’s Materials Sciences Division, led a study in which silver nanocrystals of a variety of polyhedral shapes self-assembled into exotic millimeter-sized superstructures through a simple sedimentation technique based on gravity.
‘We have shown through experiment and computer simulation that a range of highly uniform, nanoscale silver polyhedral crystals can self-assemble into structures that have been calculated to be the densest packings of these shapes,’ Yang says.”
Peidong Yang, a chemist who holds joint appointments with Berkeley Lab and UC Berkeley, is a recognized nanoscience authority. (Photo by Roy Kaltschmidt, Berkely Lab Public Affairs)
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A U.S. Department of Energy National Laboratory Operated by the University of California
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