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

The photoluminescence intensity at 580 nm for 2-3 nm ZnS doped with (Formula presented) (ZnS:Mn) increases after modification by acrylic acid (AA). (Formula presented) electronic states are examined by electron paramagnetic resonance (EPR) spectroscopy. Signal I with (Formula presented) and hyperfine coupling constant (Formula presented) and signal II with (Formula presented) and (Formula presented) are observed in the EPR spectrum of unmodified ZnS:Mn. Signal I is assigned to isolated (Formula presented) 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 (Formula presented) ions near the surface.