High-Resolution Imaging and Spectroscopy of Multipolar Plasmonic Resonances in Aluminum Nanoantennas

Abstract

We report on the high resolution imaging of multipolar plasmonic resonances in aluminum nanoantennas using electron energy loss spectroscopy (EELS). Plasmonic resonances ranging from near-infrared to ultraviolet (UV) are measured. The spatial distributions of the multipolar resonant modes are mapped and their energy dispersion is retrieved. The losses in the aluminum antennas are studied through the full width at half-maximum of the resonances, unveiling the weight of both interband and radiative damping mechanisms of the different multipolar resonances. In the blue-UV spectral range, high order resonant modes present a quality factor up to 8, two times higher than low order resonant modes at the same energy. This study demonstrates that near-infrared to ultraviolet tunable multipolar plasmonic resonances in aluminum nanoantennas with relatively high quality factors can be engineered. Aluminum nanoantennas are thus an appealing alternative to gold or silver ones in the visible and can be efficiently used for UV plasmonics.

Localized Plasmonic Resonances of Prolate Nanoparticles in a Symmetric Environment: Experimental Verification of the Accuracy of Numerical and Analytical Models

“…The MNPBEM code developed by Hohenester and Trügler [89][90][91], which in recent years has been extensively used for the simulation of plasmonic nanoparticles [92][93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108], is used for these simulations. Further details can be found in Sec.…”

“…REV. APPLIED 9, 064038 (2018) 064038-10 plasmonic excitations in the nanoparticles studied here from the collected experimental STEM-EELS data (as was also done by other groups for other NPs [46,102,119,120] Figure 7 shows the dipolar plasmonic mode energies of all 66 studied nanoparticles versus their aspect ratio A ¼ L=w (where L is the length and w the width of the nanoparticle). The results of different length ranges of the nanoparticles (L < 30 nm, 30 nm < L < 60 nm, 60 nm < L < 90 nm, and 90 nm < L) are coded with different colors (dark blue, green, orange, and light blue) in Fig.…”

Unveiling Nanometer Scale Extinction and Scattering Phenomena through Combined Electron Energy Loss Spectroscopy and Cathodoluminescence Measurements

“…The boundary element method (BEM) numerical simulations are achieved using either BEM-3D 37 or the MNPBEM toolbox 53 with its EELS/CL extension, 54 with the CL spectra computed as described in ref 55. Simulations including a substrate are performed by adding a 5 nm thin cylinder upon which the nanoprism stands completely.…”

Plasmonics in the Ultraviolet with Aluminum, Gallium, Magnesium and Rhodium

“…Among these methods are lithography, laser ablation and chemical synthesis. This includes nanorods [28][29][30], nanodisks [22] or flat triangles [31,32]. The main disadvantage is its inherent high tendency to oxidation.…”

“…This is why this oxide layer is sometimes described as a "protective" layer. Recent experiments on Al nanorods, have shown that high-order resonant modes are more confined inside the oxide-shell [30].…”