Twofold-coordinated tin centers as UV sensitizers of trivalent dysprosium ions

Phosphate glasses containing Dy^{3 +} ions were co-doped with tin (II) oxide with the purpose of investigating on the sensitizing effects of tin species on the luminescence of Dy^{3 +} ions. The glasses were prepared by the melt-quenching technique and the spectroscopic properties were assessed by optical absorption and photoluminescence spectroscopy. The data indicated the presence of twofold-coordinated Sn centers as the tin-related luminescent species in the glass host. A remarkable Dy^{3 +} ions emission was observed under UV excitation in the co-doped glass in connection to excitation of the Sn centers. The data shows unambiguously the role of tin as a sensitizer of Dy^{3 +} ion luminescence. Likely energy transfer processes that result in populating the ⁴F_9/2 emitting state in Dy ^{3 +} are discussed.