We present to a general readership an overview of the rich variety of phenomena and applications that arise from the interaction of metallic nanoparticles with light. First, we present the fundamental physics of localized surface plasmon resonances, the most relevant theories and numerical methods, as well as optical detection schemes. Finally, we explain how the localized surface plasmon resonances are currently exploited for the nanoscale manipulation of light, heat and forces in various applications and experimental investigations.

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In this work we study the optical properties of silver metal nanosphere pairs by means of rigorous electrodynamics calculations based on the generalized multiparticle Mie theory. By correlating the dipole longitudinal plasmon wavelength with its corresponding value of the real part of the dielectric constant, and based on the dipole quasi-electrostatic approximation, we were able to derive a new plasmon ruler equation for the longitudinal dipole plasmon resonance of Ag dimers, suitable for a wide range of interparticle distances and radii. The new resonance condition equation, at variance with previous work on noble metal nanoparticle pairs, takes into account empirically retardation effects and multipole interactions, being a novel, accurate, and potentially useful tool for future applications in plasmonic nanometrology or sensor devices.

The realization of materials at the nanometer scale creates new challenges for quantitative characterization and modeling as many physical and chemical properties at the nanoscale are highly size and shape-dependent. In particular, the accurate nanometrological characterization of noble metal nanoparticles (NPs) is crucial for understanding their optical response that is determined by the collective excitation of conduction electrons, known as localized surface plasmons. Its manipulation gives place to a variety of applications in ultrasensitive spectroscopies, photonics, improved photovoltaics, imaging, and cancer therapy. Here we show that by combining electron tomography with electrodynamic simulations an accurate optical model of a highly irregular gold NP synthesized by chemical methods could be achieved. This constitutes a novel and rigorous tool for understanding the plasmonic properties of real three-dimensional nano-objects.

The scattering properties of multipole plasmon resonances sustained by silver and gold nanorods (NRs) are investigated using classical electrodynamics DDA (discrete dipole approximation) simulations. The angular distribution of the scattered light is examined as a function of the multipole order, NR length, noble metal nature, and dielectric environment. For a given multipole order, the dependence of the differential scattering cross section on the different variables is rationalized in terms of two different contributions to the differential scattering cross sections: the resonant wavelength and the Mueller matrix element S 11 . It was found that the magnitude of S 11 for a given multipole order is mainly determined by its quantum scattering yield. By comparing the scattering patterns of finite cylinders with the radiation scattered by a point light source, it was possible to characterize and gain physical insight on the different resonance modes.