VUV 5 d – 4 f luminescence of Gd 3+ doped into CaF 2

High‐resolution (∼1 Å) emission and excitation spectra as well as luminescence decay kinetics have been studied for CaF 2 doped with Gd 3+ (0.1%) and Ce 3+ (0.05%) under excitation by synchrotron radiation near and above the edge of interconfigurational 4 f 7 – 4 f 6 5 d transitions in Gd 3+ and 4 f – 5 d transitions in Ce 3+ . 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 Gd 3+ 4 f 7 – 4 f 6 5 d excitation spectrum. The obtained results confirm that the VUV luminescence observed in CaF 2 :Gd 3+ ,Ce 3+ originates from 4 f 6 5 d – 4 f 7 radiative transitions in Gd 3+ . The vibronic structure in emission and excitation spectra of Gd 3+ d – f luminescence from the CaF 2 :Gd 3+ ,Ce 3+ crystal differs from that observed for other trivalent rare earth ions doped into CaF 2 indicating that Gd 3+ ions reside in sites of different type in CaF 2 than that of tetragonal (C 4v ) symmetry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)