Upconversion in a divalent rare earth ion: optical absorption and luminescence spectroscopy of Tm2+ doped SrCl2 (original) (raw)

Crystals of 2% Tm 2þ doped SrCl 2 were studied by variable temperature optical absorption and luminescence spectroscopy. The absorption spectrum consists of the weak 4f 13 intraconfigurational 2 F 7=2-2 F 5=2 transition around 8840 cm À1 and a series of intense parity allowed f-d transitions above 15; 000 cm À1 : Luminescence is observed from the 4f 13 2 F 5=2 excited state as well as from the lowest-energetic 4f 12 5d excited state at all temperatures between 10 and 300 K: Upconversion luminescence from the latter is observed after cw-(lamp) excitation at 8840 cm À1 into 2 F 5=2 at 15 K; as well as after pulsed (laser)