Today’s nanotechnology has enabled the fabrication of metallic nanoparticles with a variety of geometries, greatly advancing the research field of plasmonics. The complementary system of the inverted nanostructures such as nano-voids, however, has so far been limited to either 2D holes or spherical voids, owing to the difficulty in creating voids with well-defined 3D geometries. Here we present the first localized surface plasmon resonance (LSPR) study, both experimentally and theoretically, on aluminium nano-voids in the shape of truncated octahedra.
Nano-voids were made in high-purity aluminium using an annealing and quenching treatment.1 To characterize LSPRs of voids, we used electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) – an aberration-corrected FEI Titan operating at 80 kV. The lower accelerating voltage mitigates irradiation damage on aluminium, which is critical to perform reliable STEM-EELS mapping on voids. To confirm experimental results, electrodynamic EELS calculations were carried out based on electron-driven discrete dipole approximation (e-DDA).2
Our results show that these aluminium nano-voids exhibit strongly localized field enhancements, with the LSPR energies 10.7 – 13.3 eV (116 – 93 nm), well beyond the conventional LSPR spectrum range. The LSPR tunability was demonstrated by tailoring the shape of nano-voids using controlled electron irradiation. Furthermore, owing to the simplicity of the nano-void system which is free of aluminium oxidation and supporting substrates, we demonstrate that the intrinsic LSPR properties of pure Al nanoparticles can be revealed from nano-voids characterization using the sum rule for the complementary systems. Combined with the low cost and mass producibility of Al, our results indicate that both the Al nano-voids and nanoparticles can effectively expand the available plasmonic spectrum to the extreme UV region (≤ 124 nm), which opens possibilites for applications such as plasmon-enhanced UV photoemission spectroscopy and photoionization.
This work was supported by the Australian Research Council (ARC) grant DP110104734 and DP150104483 and a Monash University IDR grant. The FEI Titan3 80-300 S/TEM at Monash Centre for Electron Microscopy was funded by the ARC Grant LE0454166.
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To cite this abstract:Ye Zhu, Philip Nakashima, Alison Funston, Laure Bourgeois, Joanne Etheridge; Localized surface plasmon resonance mapping on aluminium voids with three-dimensional nanostructures. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/localized-surface-plasmon-resonance-mapping-on-aluminium-voids-with-three-dimensional-nanostructures/. Accessed: May 26, 2020
EMC Abstracts - https://emc-proceedings.com/abstract/localized-surface-plasmon-resonance-mapping-on-aluminium-voids-with-three-dimensional-nanostructures/