Luminescence from the³P₂state of Tm³⁺

Using various ultraviolet laser excitation lines between 199.8 nm (50 034 cm-1) and 266 nm (37 583 cm-1), emission transitions have been observed and assigned for the first time from the3P2term of Tm3+, located near 37 500 cm-1. The most intense transitions are to the terminal3H6and3F4states, and are almost entirely vibronic in character for Tm3+in elpasolite cubic lattices. In other systems, these transitions may find application in ultraviolet lasers. The interpretation of the3P2→3H4emission transition in Cs2NaTmCl6reveals electron-phonon coupling phenomena analogous to that in the3H6ground state, and which provides the explanation for the enormous deviation between the experimental and calculated energy of the3H4Γ4level. We also report the quantum cutting of blue to infrared radiation in Cs2LiTmCl6and the upconversion from1D2to3P2in Cs2NaTmCl6.