VUV 5d – 4f luminescence of Gd3+ doped into CaF2

High‐resolution (∼1 Å) emission and excitation spectra as well as luminescence decay kinetics have been studied for CaF2 doped with Gd3+(0.1%) and Ce3+(0.05%) under excitation by synchrotron radiation near and above the edge of interconfigurational 4f7 – 4f65d transitions in Gd3+ and 4f – 5d transitions in Ce3+. The fast (τ ∼ 8.5 ns) VUV luminescence has been detected from the crystal the spectrum of which shows zero‐phonon line at 77660 cm–1 and dominating vibronic line at energy interval ∼370 cm–1. The vibronic structure in VUV emission spectrum well correlates with that observed at the onset of the Gd3+ 4f7 – 4f65d excitation spectrum. The obtained results confirm that the VUV luminescence observed in CaF2:Gd3+,Ce3+ originates from 4f65d – 4f7 radiative transitions in Gd3+. The vibronic structure in emission and excitation spectra of Gd3+ d – f luminescence from the CaF2:Gd3+,Ce3+ crystal differs from that observed for other trivalent rare earth ions doped into CaF2 indicating that Gd3+ ions reside in sites of different type in CaF2 than that of tetragonal (C4v) symmetry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)