Anomalous 10-ns emission in Ce-doped Cs3LuCl6

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 Ce doped in Cs3LuCl6. Wavelengths between 50–200 nm and longer than 215 nm have zero excitation efficiency. Excitation and emission spectra of Cs3LuCl6 :Ce 31 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 Ce doublet emission from the lowest 5d level to the F5/2 ~368 nm! and F7/2 levels ~400 nm! of the 4 f 1 configuration is observed. Autoionization of the 5d electron to conduction band states followed by the direct transition to the F levels is proposed to explain the 281 nm emission and to explain the absence of emission under across bandgap excitation.