Multipolar Plasmonic Resonances in Silver Nanowire Antennas Imaged with a Subnanometer Electron Probe

Abstract

We detect short-range surface plasmon-polariton (SR-SPP) resonances setup in individual silver nanoantenna structures at high-spatial resolution with a scanning, subnanometer electron probe. Both even and odd multipolar resonant modes are resolved up to sixth order, and we measure their spatial distribution in relation to nanoantenna structures at energies down to 0.55 eV. Fabry-Perot type SR-SPP reflection phase shifts are calculated from direct measurements of antinode spacings in high-resolution plasmonic field maps. We observe resonant SR-SPP antinode bunching at nanoantenna terminals in high-order resonant modes, and antinode shifts in nonhomogeneous local environments. Finally, we achieve good agreement of our experimental SR-SPP maps with numerical calculations of photon excited near fields, using a novel integrated photon excitation geometry.

Fabry-Perot Plasmonic Resonances in Silver Nanowire Antennas Imaged with a Sub-Nanometer Electron Probe

“…The detected resonance energies range from near-infrared to ultraviolet photon energies. The filtered images are in good agreement with simulated near-field distributions, calculated at resonant energies and averaged over all in plane wavevector orientations as discussed in details elsewhere [3].The direct measure of the SPP intensity profile at resonance, carried out on multiple rods and mode orders, enabled the measurement of the SPP wavelength and phase relative to the nanoantenna structure as shown in Fig. 2.…”

The Substrate Effect in Electron Energy-Loss Spectroscopy of Localized Surface Plasmons in Gold and Silver Nanoparticles

“…3 accessible, allowing LSPs to be probed and studied with sub-nanometer spatial resolution 6,8,[22][23][24][25][26] . TEM requires specimens thin enough to be electron transparent (typically below 100 nm) and therefore, plasmonic nanoparticles studied by EELS are typically supported on thin membranes 6,8,27 or buried in a thin embedding material 28 .…”

“…TEM requires specimens thin enough to be electron transparent (typically below 100 nm) and therefore, plasmonic nanoparticles studied by EELS are typically supported on thin membranes 6,8,27 or buried in a thin embedding material 28 . In many cases, modest attention has been given to the influence of the substrate, where it is either not taken into account 6,8,29 or assumed to act as a homogeneous background medium, whose effective permittivity is fitted by comparing simulations to experimental results 27,30,31 . More recently, a number of studies have focused on specific substrate induced effects in EELS, such as mode splitting and energy transfer between LSPs and the substrate in the optical response of truncated nanospheres and nanocubes [32][33][34][35] .…”

Even Hard-Sphere Colloidal Suspensions Display Fickian Yet Non-Gaussian Diffusion

“…1,2 Following those pioneering studies, electron beams have revealed many of the properties of plasmons through energy-loss and cathodoluminescence spectroscopies, which benefit from the impressive combination of high spatial and spectral resolutions that is currently available in electron microscopes and that allows mapping plasmon modes in metallic nanoparticles and other nanostructures of practical interest. [3][4][5] However, plasmon creation rates are generally low, thus rendering multiple excitations of a single plasmon mode by a single electron extremely unlikely.…”