Silver Nanoprisms Acting as Multipolar Nanoantennas under a Low-Intensity Infrared Optical Field Exciting Fluorescence from Eu³⁺

A silver nanoprism (Ag NP) generates a near field due to multipolar surface plasmon resonance (SPR) and lightening rod effects and acts as a multipolar nanoantenna. The ability of Ag NPs to create such an effect even under an infrared (IR) optical field far off of resonance from the SPR frequency is demonstrated through finite difference time domain simulations of exact Ag NPs and hybrids. The conclusive experimental proof of such a near field around Ag NPs under low-intensity (1.5 mW) IR (980 nm) light came when it could excite fluorescence from YVO₄/Eu³⁺ nanoparticles that otherwise do not fluoresce under IR. The results open up new vistas for exclusive plasmonic excitation of fluorescence through metal NP hybrids/ensembles