Formation and Distinctive Decay Times of Surface- and Lattice-Bound Mn2+ Impurity Luminescence in ZnS Nanoparticles

The Mn2+ impurity luminescence decay of Mn2+-doped ZnS nanoparticles has been clearly distinguished from ZnS host emission decay by measuring transient absorption and emission kinetic profiles in the picosecond−millisecond time domain. The Mn2+ luminescence for the doped sample shows two decay components of 0.18 and 2 ms. The fast one is attributed to surface-bound Mn2+ impurities and the slow one to lattice-bound Mn2+ impurities. In comparison, the slowest component of ZnS host emission decays within 20 ns. Moreover, excitation-energy transfer from ZnS host to Mn2+ impurity is also measured to occur on the time scale of 700 ps.