Experimental evidence of luminescence quenching at long coupling distances in europium (III) doped core-shell gold silica nanoparticles

Abstract

Localized surface plasmons can modify linear optical responses of materials located in their vicinity. In particular, rare earth ions luminescence can be enhanced by gold nanoparticles. Luminescence exaltation is a complex phenomenon that depends on multiple parameters, a critical one being the coupling distance between the emitting species and the plasmonic core. An original multilayer nanostructure designed to precisely control the distance between the gold cores and the luminescent ions, and to study its effect on the luminescent properties is presented here. Homogeneous silica shells with controlled thicknesses adjustable from 2 to 50 nm and rare earth ion doping rates up to 2 × 1020 Eu/cm3 of silica were deposited onto gold nanospheres. These original nanostructures are then incorporated into densified sol–gel silica composites with high-optical quality. Luminescence properties are studied for increasing gold–europium (III) distances. Strong luminescence quenching is evidenced for coupling distances up to 28 nm.