P. Dorenbos, E. V. D. van Loef, C. W. E. van Eijk, K. W. Krämer and H. U. Güdel
Anomalous 10-ns emission in Ce³⁺-doped Cs₃LuCl₆
Phys. Rev. B 68, 125108/1-6 (2003)                 

Abstract: An emission at 281 nm with a 10.5 ns single exponential decay and a highly selective, narrow excitation region between 202 and 211 nm has been observed for Ce³⁺ doped in Cs₃LuCl₆. Wavelengths between 50–200 nm and longer than 215 nm have zero excitation efficiency. Excitation and emission spectra of Cs₃LuCl₆:Ce³⁺ in the 10–300 K temperature range were excited by pulsed synchrotron radiation between 50–335 nm. In addition to this new emission, the conventional Ce³⁺ doublet emission from the lowest 5d level to the ²F_5/2 (368 nm) and ²F_7/2 levels (400 nm) of the 4f¹ configuration is observed. Autoionization of the 5d electron to conduction band states followed by the direct transition to the ²F levels is proposed to explain the 281 nm emission and to explain the absence of emission under across bandgap excitation.