Enhanced luminescence from europium complex owing to surface plasmon resonance of silver nanoparticles

The effect of Ag nanoparticles on the luminescent properties of the europium complex, where the complex is ethylenediamine tetra acetate (EDTA), was investigated in the aqueous solution system. We observed the formation of nanoparticle aggregates and the appearance of a new absorption and enhancement of the emission intensity for the complex solution containing Ag nanoparticles when the pH of the complex solution is 3–4.6. Furthermore, with increasing Ag nanoparticles concentration enhancement efficiency first increases and then decreases. The enhancement effect was discussed in terms of the effects of nanoparticle aggregates, the local electromagnetic field enhancement effect and optical absorption due to surface plasmon resonance.