Tuning Plasmons in Colloidal Nanostructures

Main list: Physics and Astronomy Colloquia

Abstract

Dr. Laura Fabris
Rutgers Materials Science and Engineering

Near field techniques, such as surface enhanced Raman spectroscopy (SERS), rely on the ability of plasmonic nanoparticles to induce localized electromagnetic field enhancements in close proximity to the metallic surface. The possibility of achieving SERS signal enhancements high enough to enable sensitive identification of analytes down to the single molecule level depends on the presence of the so-called “hot spots”, which can be located at the vertices, edges, or crevices in isolated nanoparticles or at narrow junctions between assembled nanoparticles. In turn, the presence of finely tunable hot spots correlates to the possibility of applying SERS as a reliable spectroscopic technique in the analytical and biomedical fields. Our group has worked for several years on the implementation of SERS sensing substrates and imaging tags, in which gold nanostars have demonstrated to be excellent substrates.  We have also shown that when these nanostructures are conformally coated with semiconductors such as TiO2 they can efficiently photocatalyze the evolution of hydrogen from water via near IR induced generation of hot electrons. However, for the realization of more quantitative approaches, and for a more reliable E-field manipulation, improved plasmonic platforms are necessary. For this reason, we have established a combined experimental and computational approach that has led us to synthesize by design highly monodispersed gold nanostars with localized surface plasmon resonances tunable between 600 and 2000 nm. We have measured their plasmonic response both at the single particle level (via EELS) and in ensemble averaged samples (UV-Vis and FT-IR spectroscopies), with excellent agreement with the theoretical predictions obtained with 3D finite element simulations, underscoring their importance as testbeds for the design and development of 3D colloidal antennas.

  • Venue

    Dept of Physics, University Of St. Andrews North Haugh

  • Venue Info

    Lecture theatre C

  • Date

    February 22, 2019

  • Time

    From: 10h00 To: 11h00

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