Showing papers by "Alison M. Funston published in 2016"
TL;DR: A reliable and reproducible method to rapidly charge single gold nanocrystals in a solid-state device is reported, and single wavelength resonance shifts provide a much faster, more sensitive method for all surface plasmon-based sensing applications.
Abstract: A reliable and reproducible method to rapidly charge single gold nanocrystals in a solid-state device is reported. Gold nanorods (Au NRs) were integrated into an ion gel capacitor, enabling them to be charged in a transparent and highly capacitive device, ideal for optical transmission. Changes in the electron concentration of a single Au NR were observed with dark-field imaging spectroscopy via localized surface plasmon resonance (LSPR) shifts in the scattering spectrum. A time-resolved, laser-illuminated, dark-field system was developed to enable direct measurement of single particle charging rates with time resolution below one millisecond. The added sensitivity of this new approach has enabled the optical detection of fewer than 110 electrons on a single Au NR. Single wavelength resonance shifts provide a much faster, more sensitive method for all surface plasmon-based sensing applications.
48 citations
TL;DR: This work shows that EELS, in conjunction with eigenmode simulations, offers a complete characterization of the individual superstructures, and traces the evolution of both optically dark and bright modes and identifies multipolar mode contributions.
Abstract: We present a combined scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS) investigation into the mode symmetries of plasmonic nanoparticle trimer and tetramer structures. We obtain nanometer-resolved energy loss spectra for both trimer and tetramer structures and compare these to boundary element method simulations. We show that EELS, in conjunction with eigenmode simulations, offers a complete characterization of the individual superstructures, and we trace the evolution of both optically dark and bright modes and identify multipolar mode contributions. We then apply this technique to tetramer structures that exhibit an expanded range of mode symmetries for two-dimensional and three-dimensional self-assembled geometries. These findings provide a comprehensive experimental account of the available photonic states in self-assembled nanoparticle clusters.
43 citations