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-conversion exhibited. The prerequisite information for studies of these phenomena include a detailed analysis of the UV energy level scheme of the Gd3+ ion with the 4f(7) electron configuration. In this paper such a study was carried out for the tetragonal GdOCl matrix. The UV absorption spectra of GdOCl were measured at 9 K between 200 and 315 nm. The experimental energy level scheme derived from the spectra was interpreted according to the C-4v site 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 model using 14 free ion and five real c.f. parameters. A satisfactory match with an rms deviation of 21 cm(-1) between the experimental and calculated energy level schemes was obtained despite the high number of parameters and the 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 hosts. (C) 2001 Elsevier Science B.V. All rights reserved.