Bimetallic Bifrustums | August 10, 2009 Issue - Vol. 87 Issue 32 | Chemical & Engineering News
Volume 87 Issue 32 | p. 31 | Concentrates
Issue Date: August 10, 2009

Bimetallic Bifrustums

Nanocrystals with novel shape and composition may spur applications in biodiagnostics and spectroscopy
Department: Science & Technology
News Channels: Nano SCENE
Keywords: nanocrystals, surface plasmon resonance
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These gold-core/silver-shell nanocrystals look like flat triangles in the TEM image on the left (top). But an edge-on view (right) reveals that they are flattened bipyramids known as triangular bifrustums.
Credit: Nano Letters (Both)
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These gold-core/silver-shell nanocrystals look like flat triangles in the TEM image on the left (top). But an edge-on view (right) reveals that they are flattened bipyramids known as triangular bifrustums.
Credit: Nano Letters (Both)

Add two-tone triangular bifrustums to the list of unusual nanocrystal shapes and compositions that can be prepared synthetically. Researchers at Northwestern University report that they have synthesized these structures, which are truncated (flattened) triangular bipyramids as nanocrystals with gold cores and silver shells (Nano Lett., DOI: 10.1021/nl901513g). Bimetallic triangular crystals could serve as test subjects for studying relationships among crystal structure, composition, and electronic and optical properties. But the unusual crystals have been tough to synthesize. Northwestern's Hyojong Yoo, Chad A. Mirkin, George C. Schatz, and coworkers succeeded in making the tiny structures by using an aqueous route in which silver layers grow on gold nanoprism seed crystals. The crystals' surface plasmon resonances (SPRs)—a property that can lead to intense fluorescence and Raman spectroscopy signals—can be tuned easily throughout the UV-visible and near-IR regions by synthetically controlling the thickness of the silver shells. That property may make the crystals useful for applications in biodiagnostics and spectroscopy.

 
 
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