Electron paramagnetic resonance studies on manganese(II)-containing zinc and cadmium sulfide materials
Electron paramagnetic resonance (EPR) spectroscopy has been applied to investigate unusual phenomena observed in the photoluminescence of manganese(II)-containing zinc and cadmium sulfide materials. For manganese(II) in zinc sulfide the g value and the hyperfine splitting constant are barely dependent on the type of material (polycrystalline powder, thin film, superlattice). An anomalous emission of the polycrystalline ZnS : Mn powders calcined at 900–1000 °C in the vicinity of 520 nm is ascribed to manganese(II) in an environment with a large distortion due to oxygen impurities. For the thin films and superlattices unusual EPR spectra are observed when manganese(II) is present in cadmium sulfide: a large cubic splitting parameter of 53.8 × 10–4 cm–1 for the thin films of CdS : Mn of BaF2(111) reflects the strain due to different thermal expansions of cadmium sulfide and barium fluoride. A negative g-shift of 0.0014 for the superlattices of CdS : Mn–ZnS on BaF2(111) compared with that for the free electron implies that the covalency between manganese(II) and the environment in cadmium sulfide is affected significantly by the lattice mismatch between the alternate layers of zinc and cadmium sulfides.