VUV emission of Er 3+ and Tm 3+ in fluoride crystals

Abstract

VUV emission of several fluoride crystals doped with Er 3+ and Tm 3+ has been studied under pulsed synchrotron radiation excitation. It was shown that emission spectra of these ions in the 150–190 nm spectral range consist of both fast emission bands (decay constant in the range from a few to tens of nanoseconds) and slow ones (decay constant in the microsecond range). A model is proposed which explains the co-existence of the slow and fast components by the competition of the parity-allowed interconfiguration 4f n−1 5d → 4f n radiative transitions (fast emission) and parity-forbidden intraconfiguration 4f n → 4f n transitions (slow emission). Depending on the relative position of corresponding emitting levels both fast and slow emissions, or only slow, or only fast emission are observed.