Abstract
We proposed an IR absorber hybrid nanoantenna comprise of two overlapping gold nanoparticles residing over larger a silica nanoparticle. A wet chemical route was employed to prepare the hybrid structure of nanoantenna. High-resolution transmission electron microscope was used to measure the size and morphology of the nanoantenna. The Hybrid nanoantenna was excited by electron beam to investigate the optical response over a large wavelength range using Electron Energy Loss Spectroscopy. The beam of the electron was focused and we measured the electron energy loss spectra at different point of interest, which confirmed the of Low Energy Surface Plasmon Politron resonances in the IR region. The optical response of the nanoantenna was simulated numerically by employing Electric Hertzian dipole using finite element method with frequency domain solver in CST Microwave Studio. We used the Electric Hertzian dipole approach for the first time to model the Electron Energy Loss Spectroscopy experiment. The Electron Energy Loss Spectroscopy experimental results with their numerically simulated values confirmed the plasmonic resonance at the interface of the two overlapped gold nanoparticles.
Highlights
Nanoantennas are able to confine the visible or infrared light into the sub-diffraction volume, through the collective excitation of conduction electrons at the boundaries of plasmonic nanostructures [1,2]
The Energy Loss Spectroscopy (EELS) beam was focused, and spectra were measured at different locations on the two overlapped Au nanoparticles
The EELS measured data reveal that Low Energy Surface Plasmon Politron resonances (LE-SPPr) occurs across the thin interfacial area between Au nanoparticles
Summary
Nanoantennas are able to confine the visible or infrared light into the sub-diffraction volume, through the collective excitation of conduction electrons at the boundaries of plasmonic nanostructures [1,2]. Several approaches have been made for solving of Maxwell equations with an electron beam as excitation source Some of these solutions have been used successfully to model the EELS experimental data. These Approaches include Discrete Dipole Approximation (DDA), Boundary Element Method (BEM), and Finite-Difference Time-Domain (FDTD) [18,19,20]. The simulation was performed by employing Frequency domain Finite Element Method (FEM) using Computer Simulation Technology (CST) Microwave Studio In these numerical analyses, the plasmonic gold nanoparticles were excited by an Electric Hertzian dipole (EHD) driven with a small current [21]. A modified Drude model has been used to include the size effects of gold nanoparticles [21,22]
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