Optimization of extinction from surface plasmon resonances of gold nanoparticles

Abstract

We present a method to determine the total extinction of laser light due to excitations of the surface plasmon modes in gold nanoparticles, even for very large particle concentrations. The method uses the Mie theory efficiency parameter for single-particle scattering and absorption, a single-particle extinction parameter. We have previously shown that, by properly screening the scattered light, we can determine the extinction of laser light when the beam transverses as many as ten scattering mean free paths in a dense medium, i.e. in the presence of significant multiple scattering. We present the application of the method to the total extinction due mainly to the excitations of the surface plasmon resonance in gold nanoparticles. Although the results obtained from measurements in this multiple-particle medium are explained in terms of the single-particle Mie extinction parameter, we find that the optimum particle size for maximum multiple-scattering extinction is smaller than that for the maximum single-particle extinction parameter predicted by the Mie theory.

Gold Nanoparticles in Chemical and Biological Sensing

“…199 The refractive index dependence on solvent and ligand can alter the optical thickness, which can be used for detecting impurities due to different refractive indexes of gold oxide and gold chloride. 200 The core charge, as mentioned above, is influential in determining SPB energy, causing shifts to higher energy with excess electronic charge and to lower one with electron deficiency. 199,201–203 The mechanism of the dominant electronic dephasing was proposed to be that only electron-electron interactions were involved rather than electron-photon coupling.…”

Sensors based on monochromatic interrogation of a localised surface plasmon resonance

“…In the first, the optical path length through the sensing volume is significant, and the sensing nanoparticles are both dilute and randomly distributed throughout the volume of the optical path. In this case, the transmittance can be estimated (provided that multiple scattering events are negligible [29]) by the Beer-Lambert law:…”

“…where N the number of particles per unit volume, x the thickness of the sensor coating, and C ext the extinction cross-section [30]. The term N.x.C eff is a measure of the 'optical thickness' of the sample [29]. Since…”

“…As the concentration of the nanoparticles increases, Eq. (3) will start to underestimate the extinction [29] and hence over-estimate the transmittance.…”

Microfabrication Technology for Millimeter-Wave Photonic Systems on Si

“…That is, the addition of H 2 O 2 aq causes some oxidized gold compounds to form when the gold removal rate is high, despite gold's chemical stability. These oxidized compounds are possibly oxide and/or halide (iodide) (14)～ (16) . Figure 9 shows the XPS spectra for the I3d region.…”