Abstract
We demonstrated that the nanostructures comprising silver cores and dense layers of Y2O3:Er separated by a silica shell are an excellent model system to study the interaction between upconversion materials and metals in nanoscale. This architecture allows for versatile control of the Y2O3:Er-metal interaction through control of the silica dielectric spacer thickness and the metal-core size. Finally, the nanoparticles are potentially Interesting as fluorescent labels in. for instance (single particle), imaging experiments or bioassays which require low background or tissue penetrating wavelengths.