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

We report a simple, rapid, and quantitative wide-field technique to measure the optical extinction $σext$ and scattering σ_sca 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 σ_sca 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.