On the sensitization of the Pr3+ Photon Cascade Emission by the 4fn−15d1 states of the Tm3+ and Nd3+ ions in YF3

Abstract The sensitization of the Pr 3+ Photon Cascade Emission by the 4f n −1 5d 1 states of the Tm 3+ and Nd 3+ ions in YF 3 has been studied at room temperature and over a wide range of sensitizer concentrations. Strong sensitization of the Pr 3+ 1 S 0 → 1 I 6 emission transition is produced when exciting into the interconfigurational transition (4f n → 4f n −1 5d 1 ) of the sensitizer ions ( λ ex = 147 nm). However, the luminescence efficiency of the Pr 3+ 3 P 0 state decreases with increasing proportions of the Tm 3+ and Nd 3+ ions because of the nonradative energy transfer that occurs between the 4f n states of Tm 3+ /Nd 3+ ions and the Pr 3+ 3 P J state. The various energy transfer channels that are operative between the 4f 2 and 4f 12 states of the Pr 3+ and Tm 3+ ions are identified and characterized. It is noteworthy that the addition of Tm 3+ and Nd 3+ ions has a detrimental effect on the luminescence efficiency of the Pr 3+ 1 S 0 state when exciting directly into the Pr 3+ ion ( λ ex = 185 nm). This is a surprising result since there is an absence of energy matching between the Tm 3+ 4f 12 /4f 11 5d 1 and the Pr 3+ 1 S 0 states and because efficient Tm 3+ → Pr 3+ energy transfer is observed for λ ex = 147 nm. The possible reasons for this are discussed.