Photoluminescence via plasmon resonance energy transfer in silver nanocomposite glasses

This paper reports the first spectroscopic demonstration of photoluminescence (PL) owing to plasmon resonance energy transfer (PRET) from silver nanoparticles (NPs) to luminescent species in glass. Optical absorption and PL spectroscopy experiments performed on the melt-quenched silver-doped glass indicate the presence of single Ag+ ions, Ag+ - Ag+ and Ag+ - Ag0 pairs, and Ag NPs. After thermal processing of the material, nonradiative energy transfer from the Ag+ - Ag0 luminescent centers to Ag NPs is observed by uniform suppression of band emission and the vanishing of the excitation band associated. Furthermore, evidence for PRET is observed after glass heat treatment by the appearance of a new excitation band near the surface plasmon resonance peak of Ag NPs at about 420 nm, when emission of silver pairs is monitored around 550 nm. In fact, excitation at 420 nm leads to a band emission centered around 530 nm indicating that the excitation of luminescent silver species indeed takes place via PRET. The luminescence is interpreted as arising from a Ag NP→ Ag+ - Ag0 → Ag+ - Ag+ energy transfer scheme.