Linear and Polygonal Assemblies of Plasmonic Nanoparticles: Incident Light Polarization Dictates Hot Spots

The assemblies of metal nanoparticles, thanks to their intriguing plasmonic properties, have provided numerous opportunities for manipulating light at the.nanoscale. Driven by the recent experimental success in using polarization of light as a handle to control plasmonic features, we consider the organization of spherical gold nanoparticles as linear and polygonal assemblies (n = 1-6) and perform a detailed analysis of the optical features as a function ofthe polarization of the incident light (theta = 0 degrees, 30 degrees, 60 degrees, and 90 degrees) using the finite-difference time-domain (FDTD) method. Our investigations reveal that the extinction features in linear chains show a strong dependence on the state of polarization of the source, whereas those in the polygonal assemblies are polarization-insensitive. However, the hot spot distribution in polygonal assemblies is strongly dependent on the polarization state of the incident light, thereby giving rise to interesting control over hot spot features for surface-enhanced spectroscopy. Finally, we also comment on the role of the wavelength of light, size of the metal particle, and the gap size between the particles in governing the plasmonic properties of the assemblies.