Energy levels of Pr3+:GdOCl under pressure

Abstract

Excitation and luminescence spectra of Pr3+ in GdOCl weremeasured in the spectral range from 11 000 cm-1 to22 500 cm-1. At ambient pressure a total of 54 spectrallines were observed. Some of these lines cannot be explained bytransitions between crystal-field levels of the regular Pr3+ site in GdOCl. Possible explanations of these lines arediscussed. Under pressure up to 16 GPa, all lines exhibit ared-shift, from which a part of the energy level scheme of the4f2 configuration could be derived. From the 34 levels atambient pressure, 31 could also be obtained under pressure. Theenergy level scheme is described in terms of the free-ion parameters(F k, α, β, γ, ζ, Mk, P k) andcrystal-field parameters (B 20, B 40, B 44, B 60,B 66). The variations of these parameters under pressure weredetermined. Surprisingly, the crystal-field strength, calculatedfrom the crystal-field parameters, first shows a slight decreasewith increasing pressure.