Polarization-resolved extinction and scattering cross-sections of individual gold nanoparticles measured by wide-field microscopy on a large ensemble

Abstract

We report a simple, rapid, and quantitative wide-field technique to measure the optical extinction σext and scattering σsca cross-section of single nanoparticles using wide-field microscopy enabling simultaneous acquisition of hundreds of nanoparticles for statistical analysis. As a proof-of-principle, we measured gold nanoparticles of 40 nm and 100 nm diameter and found mean values and standard deviations of σext and σsca consistent with the literature. Switching from unpolarized to linearly polarized excitation, we measured σext as a function of the polarization direction and characterized the nanoparticle asphericity. The method can be implemented cost-effectively on any conventional wide-field microscope and is applicable to any nanoparticles.