Energy Levels and Luminescence of Dysprosium(III) in a Fluoride Glass With and Without Manganese(II)

Abstract

Luminescence, excitation, and emission spectra are studied of vitreous {36 PbF₂ : 24 ZnF₂ : 35 GaF₃ : 2 AlF₃ : 3 YF₃ : 2 DyF₃; mole ratios of the anhydrous fluorides} and in the analogous glass (with and without DyF₃) having ZnF₂ replaced by MnF₂. Intense narrow-band emission at λ = 483 and 580 nm is due to the 4f⁹ level ⁴F_9/2 (lifetime 0.4 ms, shortened by a factor 30 in presence of MnF₂, due to Dy^III → Mn^II energy transfer above 21000 cm^-1). Weak emission at 454 nm has a long-time component due to thermalization to (Dy^III)⁴I_15/2 and possibly short-lived ⁴F_7/2 to ⁶H_13/2. The transition to the ground state may contribute to a broadened, weak emission at 391 nm (0.01 ms). When Mn^II and Dy^III are simultaneously present, the broad band around 592 nm emitted by the lowest quartet state of Mn^II has the lifetime shortened from 0.7 to 0.2 ms, even the former value being low because of the large manganese concentration. Energy transfer from Mn^II has previously been observed in the case of near-infrared line emission of neodymium(III) and thulium(III) in such fluoride glasses.