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 ${\mathrm{Ce}}^{3+}$ doped in ${\mathrm{Cs}}_3{\mathrm{LuCl}}_6.$ Wavelengths between 50–200 nm and longer than 215 nm have zero excitation efficiency. Excitation and emission spectra of ${\mathrm{Cs}}_3{\mathrm{LuCl}}_6:{\mathrm{Ce}}^{3+}$ 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 ${\mathrm{Ce}}^{3+}$ doublet emission from the lowest $5d$ level to the ${}^2{F}_{5/2}$ (368 nm) and ${}^2{F}_{7/2}$ levels (400 nm) of the ${4f}^1$ configuration is observed. Autoionization of the $5d$ electron to conduction band states followed by the direct transition to the ${}^{2}F$ levels is proposed to explain the 281 nm emission and to explain the absence of emission under across bandgap excitation.

• Received 19 May 2003

DOI:https://doi.org/10.1103/PhysRevB.68.125108