The optical properties of metal nanocrystals (NCs) have been exploited in many applications, including for medicine, energy, and chemical sensing. The diversity of these applications arises from the sensitivity of the localized surface plasmon resonance (LSPR) of metal NCs to their size, shape, composition, and environment. Currently there are many NCs available for use, but branched NCs have received increasing attention due to the increase in electric field enhancement that arises from the localization of the LSPR at the tips. In this study, seed-mediated co-reduction was used to achieve stellated NCs from Au seeds rich in planar defects. Interestingly, stellated NC’s conserved initial seed symmetry and rules for the growth of stellated structures from Au seeds with planar defects were established. Symmetry-dependent optical properties of stellated decahedra, icosahedra, pentatwinned rods, and triangular plates were further investigated. Specifically, finite-difference time-domain (FDTD) simulations were employed to probe the near-field enhancements and far-field scattering of these NCs. The near- and far-field behavior of the stellated NCs were found to be orientationally dependent with respect to incident light direction. The NC’s dependency on the nature of the light is attributed not only to its orientation, but also to its shape and symmetry. Furthermore, the high monodispersity of these stellated NCs facilitates the self-assembly of 2-D superlattices that exhibits new near- and far- field behaviors. The findings of this work illustrate how NC’s symmetry, shape, and environment influence their plasmonic properties.

Optical properties of stellated metal nanocrystals grown from seeds with planar defects

255th National Meeting (2018)

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