Second harmonic generation of single metallic nanoparticles

Single metallic nanoparticle sensitivity in liquid solution was achieved with hyper Rayleigh scattering (HRS). The study of the HRS intensity fluctuations over time was performed for several dilutions of the nanoparticle solution. Histograms of the HRS intensity counts were then obtained. These histograms exhibit a Gaussian profile down to low concentrations before evolving towards Poisson distributions at very low concentrations, demonstrating that the single particle sensitivity is obtained. Based on these results, we were then able to achieve the three-dimensional mapping of immobile 150 nm gold metallic nanoparticles dispersed in a homogeneous transparent polyacrylamide matrix. Polarization resolved measurements were also performed allowing for a clear identification of the harmonic light generated by single gold metallic nanoparticles.