Effect of sapphire substrate on the localized surface plasmon resonance of aluminum triangular nanoparticles

In this paper, we explore the effect of the sapphire substrate on the localized surface plasmon resonance of Al triangular nanoparticles fabricated by nanosphere lithography. We find an obvious shoulder peak which is rarely noticed before as well as a main peak in the the ultraviolet range of the extinction spectrum. Then the electric field distributions surrounding the single Al triangular nanoparticle have been further investigated by numerical simulation using the finite-difference time-domain method. By analyzing the simulation results, we demonstrate that the two peaks in the extinction spectrum are originated from the hybridization of dipolar and quadrupolar modes when the sapphire substrate exists. And this work may provide a better understanding of the effect of sapphire substrate on the localized surface plasmon resonance properties of aluminum triangular nanoparticles.