Molecular electronic model, vibronic interactions, and selective intensity transfer for levels [formula omitted] of Mn2+ in ZnS and ZnSe

Abstract

The electronic fine structure of the orbital triplet levels 4T2(G) of d5 ions in tetrahedral II–VI compounds is determined from an extended molecular model involving the first- and second-order molecular spin–orbit (MSO) interaction. For the levels 4T2(G) of Mn2+ in cubic ZnS, it is shown that the first-order MSO interaction is almost identical to that predicted by the crystal-field (CF) model. For the levels 4T2(G) of Mn2+ in cubic ZnSe, the splittings of the fine structure lines due to the first-order MSO interaction is much larger than the splitting predicted by the CF-model. Concerning the second-order (MSO) interaction, it is shown that the splitting of the levels Γ8(5/2) and Γ6 at lower energy drastically depends on the spin–orbit coupling constants of the electrons p of the ligands. Finally, an analysis is made of the coupling to ε-vibrational modes from Ham's model, and the selective intensity transfer observed on the fine structure lines of the level 4T2(G) of Mn2+ in ZnS and ZnSe is analyzed in detail.