EPR study ofMn2+electronic states for the nanosized ZnS:Mn powder modified by acrylic acid

Abstract

The photoluminescence intensity at 580 nm for 2–3 nm ZnS doped with ${\mathrm{Mn}}^{2+}$ (ZnS:Mn) increases after modification by acrylic acid (AA). ${\mathrm{Mn}}^{2+}$ electronic states are examined by electron paramagnetic resonance (EPR) spectroscopy. Signal I with $g=2.0024\mathrm{}$ and hyperfine coupling constant $|A|=6.9\mathrm{}\mathrm{mT}$ and signal II with $g=2.0013\mathrm{}$ and $|A|=9.0\mathrm{}\mathrm{mT}$ are observed in the EPR spectrum of unmodified ZnS:Mn. Signal I is assigned to isolated ${\mathrm{Mn}}^{2+}$ ions substitutionally incorporated in cubic ZnS. The intensity of signal II relative to signal I increases with decreasing the S/Zn ratio, while its intensity decreases after modification of the ZnS:Mn nanoparticles by AA. Signal II is, therefore, attributed to the ${\mathrm{Mn}}^{2+}$ ions near the surface.