VUV 5d-4f luminescence of Gd3+ and Lu3+ ions in the CaF2 host

The first observation and characterization of Lu3+ 4f(13)5d-4f(14) luminescence from the CaF2 : Lu3+ crystal are reported, and the multisite structure in the spectra of Ce3+, Gd3+, and Lu3+ ions in the CaF2 host is analyzed with the high-resolution VUV spectroscopy technique using synchrotron radiation. It is shown that vibronic structure in the emission and excitation spectra of interconfigurational transitions in Gd3+ and Lu3+ ions doped into CaF2 differs from that observed for Ce3+ ions entering mainly at the tetragonal (C-4v) sites. However, the exact types of sites in which the Gd3+ and Lu3+ ions reside in a CaF2 lattice cannot be identified using only the obtained experimental spectroscopic data.