Influence of stacking faults in polymorphic ZnS on thed5crystal-field states ofMn2+

In polymorphic ZnS:Mn novel luminescence centers attributed to ${\mathrm{Mn}}^{2+}$ in axial crystal fields have been detected with use of site-selection spectroscopy. The shift of the zero-photon lines with respect to the cubic ${\mathrm{Mn}}^{2+}$ center within the three excited levels ${}_{}{}^4{}_{}{}^{}$ ${\mathit{T}}_1$(G), ${}_{}{}^4{}_{}{}^{}$ ${\mathit{T}}_2$(G), and ${}_{}{}^4{}_{}{}^{}$E(G) and the observed fine structures fit well into the findings of ${\mathrm{Mn}}^{2+}$ centers in stacking-faulted ZnS which have been reported earlier. The overall picture is completed by the detection of the excitation energies within the ${}_{}{}^4{}_{}{}^{}$ ${\mathit{T}}_2$(G) level of all observed ${\mathrm{Mn}}^{2+}$ centers. A general crystallographic scheme is presented to classify lattice sites with different sequences of stacking layers up to the second next Zn-S layer with respect to the impurity. Based on the lattice classification, a superposition principle is proposed which describes the effect of several lattice distortions upon the 3d transitions of ${\mathrm{Mn}}^{2+}$ on different lattice sites. The structural considerations lead to assignments of all ${\mathrm{Mn}}^{2+}$ luminescence centers to specific lattice sites, which are in good agreement with the findings in the spectra of other transition-metal impurities in stacking-faulted ZnS.