VUV emission of stoichiometric Er3+- and Tm3+-containing fluoride crystals

VUV emission of several stoichiometric fluoride crystals containing Er3+ and Tm3+ ions (LiErF4, LiTmF4, KErF4, KTmF4, BaTm2F8) has been studied with the technique of time-resolved spectroscopy under the pulsed synchrotron radiation excitation. Both fast (nanosecond) and slow (microsecond) VUV emission was detected for Tm3+-containing compounds in the studied spectral range (150-200 nm) while for Er3+-containing crystals only fast emission is observed. The difference is due to different energy level schemes for high-lying 4f states of these ions. In case of Er3+ the energy position of some high-lying 4f states is very close to that of emitting 5d levels and so the concentration quenching leads to considerable shortening of the emission. (C) 1999 Elsevier Science B.V. All rights reserved.