It was recalled that Tm3+ replaced Cd2+ in this material, and formed mainly symmetrical dimer centers and single-ion centers; both with trigonal symmetry. The energy levels of both centers were determined by means of electron paramagnetic resonance and site-selective laser spectroscopy. In order to describe the spectra, crystal-field parameters were deduced on the basis of a microscopic model that took account of the local lattice deformation which was introduced by the impurity centers, and of the quasi-resonant virtual scattering of intrinsic lattice excitations by Tm3+ ions.

Local Lattice Structure, Crystal Field and Energy Level Patterns in CsCdBr3:Tm3+ crystals. J.Heber, M.Lange, M.Altwein, B.Z.Malkin, M.P.Rodionova: Journal of Alloys and Compounds, 1998, 275-277, 181-5