Optical Extinction Spectroscopy of Oblate, Prolate and Ellipsoid Shaped Gold Nanoparticles: Experiments and Theory

Abstract

Localized Surface Plasmons (LSP) on metallic nanoparticles of different shapes are investigated by extinction spectroscopy. Experimental results are compared to simulations by a Finite-Difference TimeDomain (FDTD) method. Three different shapes of nanoparticles are compared, oblates, prolates and ellipsoids, in terms of spectral tunability of the LSP resonance (LSPR). It is found that the complete geometry of the nanoparticle must be given to truly define the LSP resonance and that ellipsoids offer the widest spectral tunability.

Depolarization effects in tip‐enhanced Raman spectroscopy

“…The localized surface plasmon resonance of gold nanoparticles with diameters of few tens of nanometers is located between 500 and 550 nm and can be red-shifted to higher wavelengths (up to 800 nm) for greater diameters (between 50 and 200 nm). [62] The resonance is, however, generally broad, varying from 50 nm (full width at half maximum) for nano-lithographied structures [61] to more than 200 nm. [62] The plasmonic scattering from gold tips has been found to result in a quite broad resonance (full width > 100 nm) extending from 550 to 800 nm, as a function of the geometry.…”

“…[62] The resonance is, however, generally broad, varying from 50 nm (full width at half maximum) for nano-lithographied structures [61] to more than 200 nm. [62] The plasmonic scattering from gold tips has been found to result in a quite broad resonance (full width > 100 nm) extending from 550 to 800 nm, as a function of the geometry. [63] Regarding our experiments, we note that, for an excitation wavelength of 514.5 nm, the wavelengths of the scattered photons of the 300-, 520-and 980-cm −1 silicon modes correspond to 523, 528 and 541 nm respectively.…”

Realization of a High‐Performance GaN UV Detector by Nanoplasmonic Enhancement

“…[13] It follows that by changing shapes of the metallic nanoparticles, the distribution of the surface charges can be modified. This allows one to tune the surface plasmon resonance frequency, [23][24][25] and manage scattering from the nanoparticles over a broad wavelength range. [11,26] However, up to now, research on the semiconductor optoelectronic devices that have been enhanced by metallic nanoparticles mainly focus on LEDs and solar cells working at visible frequencies and direct evidence of NP enhancement in UV detectors is still lacking.…”

Functional Nanostructured Plasmonic Materials

“…Electron beam lithography and focused ion beam lithography, for example, have been used to fabricate arrays of gold particles, [49,50] circular slits, [51] nanoholes, [52,53] and v-shaped grooves in metal films. [54] These fabrication methods provide high precision and control over the dimensions of the nanostructures.…”