Light induced plasmonic excitation in small nanoparticles can be used for nanosensing as well as heterogeneous catalysis. This is in part due to the localization and enhancement of the incident field. For small plasmonic nanoparticles with regular shapes such as spherical or spheroidal nanoparticles the field, in terms of multipolar plasmon modes, can be computed by solving the associated Laplace equation. For nanoparticles with arbitrary shapes this is not possible, and in such cases one can only resort to numerical methods such as the Discrete Dipole Approximation or Finite-Difference Time-Domain. In this talk, I will introduce an analytic method to approximately calculate the plasmon modes of nanostructures of arbitrary shapes. This method is based on the notion of generalized solution of the Laplace equation. As an illustration, I will present the expressions for the dipolar and quadrupolar modes for a bowtie nanoantenna and will compare these with numerical simulations. The results of this investigations provide a rational approach to the understanding of geometric effects on local field enhancements due to arbitrary plasmonic nanoparticles.

Multipolar plasmon expansion for small nanoparticles of arbitrary shapes

256th National Meeting (2018)

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