It was recalled that Cu was the transition-metal impurity, in II-VI compounds, for which the most complete experimental and theoretical data had been compiled. This made it the favorite system for studying the mechanisms which determined the optical spectra. The observed Cu2+ transitions in the present crystals were interpreted by coupling the electronic states to a local vibrational mode of E symmetry and a moderate Jahn-Teller effect with a Huang-Rhys factor of 0.8 (ZnS) or 1.1 (CdS). Parameter-free calculations were made of the magnetic-field splitting of Cu2+ centers in II-VI compounds. These exhibited a general agreement with the observed spectra. In the case of Cu2+-doped ZnS, the calculated g-factors agreed with the observed values, although a stronger non-linear behavior with respect to the magnetic field was found for some calculated energy levels. In the case of Cu2+-doped CdS, the non-linear behavior of magnetic field splitting was also reflected by the calculations, and the g-factors agreed for the 2E excited-state doublets. However, there were some differences, in the g-factors of the 2T2 ground-state doublets, which were attributed to a neglect of T2 mode coupling in Jahn-Teller calculations.

T.Telahun, U.Scherz, P.Thurian, R.Heitz, A.Hoffmann, I.Broser: Physical Review B, 1996, 53[3], 1274-86