Enhanced fluorescence from Dy3+ owing to surface plasmon resonance of Au colloid nanoparticles

Gold colloidal containing rare earth ions Dy3+ were prepared at room temperature. Fluorescence spectra of Dy3+ ions and Au colloid containing Dy3+ were measured. For solution containing Dy3+, fluorescence emission occurs at visible light wavelength region. Two emission peaks are observed at 480 nm and 570 nm respectively when the corresponding excitation wavelength is at 350 nm. When Au colloids were added to the solution containing Dy3+, both these two fluorescence peaks were enhanced. Furthermore, with the increasing Au content, the fluorescence increases first and then decreases. We believe that this increased fluorescence are due to the local field enhancement around Dy3+ ions owing to the induced higher orders of surface plasmon resonance.