(496e) Effect of Substrate, Polarization, and Orientation on the Scattering Behavior of Differently Shaped Individual Gold Nanostructures

Understanding the effects of different factors that impact the scattering behavior of plasmonic gold nanostructures is essential for many sensing and spectroscopy applications. In this work, we present a systematic study of the effect of substrate, nanostructure orientation, and polarization direction of the incident light on the scattering patterns of differently shaped individual gold nanostructures, including nanorods, nanowires, nanotriangles, nanoparticles, and nanoparticle dimers, trimers, and chains. Scattering signals from these isolated gold nanostructures in the optical far-field were captured with a polarized dark-field microscope using either a CCD imaging camera or a dispersive spectrograph. The color of these isolated gold nanoparticles, along with their optical spectra were correlated with their shape, size, and orientation as observed using high-resolution scanning electron microscopy. The scattering spectra of the individual nanostructures were captured at different polarization directions and azimuthal orientations of the incident light. The scattering from spherical gold nanoparticles and nanotriangles was seen to be mostly independent of their orientation and the polarization direction of incident light. In contrast, the scattering from gold nanorods, nanowires, and nanoparticle chains was highly dependent on both polarization and orientation of the incident light. Experimental results were compared to numerical simulations of the various nanostructures. We anticipate that this dark-field spectroscopy technique can be used for the optical characterization of various complex nanostructures, including split ring resonators whose scattering behavior depends strongly on its orientation and polarization direction of light.