Simulation of the Gd3+ energy level scheme in GdOCl

The luminescence materials of the new generation containing gadolinium have received considerable attention because of the quantum cutting and down-co nversion exhibited. The prerequisite information for studies of these pheno mena include a detailed analysis of the UV energy level scheme of the Gd3ion with the 4f(7) electron configuration. In this paper such a study was c arried out for the tetragonal GdOCl matrix. The UV absorption spectra of Gd OCl were measured at 9 K between 200 and 315 nm. The experimental energy le vel scheme derived from the spectra was interpreted according to the C-4v s ite symmetry of the Gd3+ site in the oxychloride matrix. This level scheme of 24 c.f. components representing seven L-2S+1(J) (S-8(7/2), P-6(J), 6I(J) , D-6(J)) levels was then successfully simulated by a phenomenological mode l using 14 free ion and five real c.f. parameters. A satisfactory match wit h an rms deviation of 21 cm(-1) between the experimental and calculated ene rgy level schemes was obtained despite the high number of parameters and th e sparse set of energy levels. The present results obtained for GdOCl were found consistent with the previous ones for other RE3+ ions in the REOCl ho sts. (C) 2001 Elsevier Science B.V. All rights reserved.