Browsing by Author "Skrabalak, Sara E."

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    Plasmon and compositional mapping of plasmonic nanostructures
    (SPIE, 2014) Ringe, Emilie; Collins, Sean M.; DeSantis, Christopher J.; Skrabalak, Sara E.; Midgley, Paul A.
    Recently, co-reduction of Au and Pd has allowed the synthesis of complex Au core/AuPd shell nanoparticles with elongated tips and cubic-like symmetry. Optical studies have shown strong plasmonic behavior and high refractive index sensitivities. In this paper, we describe the composition and the near-field plasmonic behavior of those complex structures. Monochromated STEM-EELS, Cathodoluminescence, and EDS mapping reveals the different resonant modes in these particles, and shows that Pd, a poor plasmonic metal, does not prevent strong resonances and could actually be extremely helpful for plasmon-enhanced catalysis.
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    Resonances of nanoparticles with poor plasmonic metal tips
    (Macmillan Publishers Limited, 2015) Ringe, Emilie; DeSantis, Christopher J.; Collins, Sean M.; Duchamp, Martial; Dunin-Borkowski, Rafal E.; Skrabalak, Sara E.; Midgley, Paul A.
    The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.