Optimization of extinction from surface plasmon resonances of gold nanoparticles

摘要

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.