Optical lines in europium-terbium double activated calcium tungstate phosphor

The Letter is devoted to the problem of the optical anisotropy of the rare-earth ions occupying low-symmetry positions in crystals. The crystal field multiplets arising from LSJ terms of Eu3+ and Tb3+ ions in the crystal field of calcium tungstate scheelite (CaWO4) are analyzed with regard to the experimental data on the low temperature photoluminescence and cathodo-luminescence spectra. The selection rules as well as an angular (polarization) dependence of the two-photon absorption are discussed. (C) 2004 Elsevier B.V. All rights reserved.