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 be en clearly distinguished from ZnS host emission decay by measuring transien t absorption and emission kinetic profiles in the picosecond-millisecond ti me domain. The Mn2+ luminescence for the doped sample shows two decay compo nents of 0.18 and 2 ms. The fast one is attributed ra surface-bound Mn2+ im purities and the slow one to lattice-bound Mn2+ impurities. Ln comparison, the slowest component of ZnS host emission decays within 20 ns. Moreover, e xcitation-energy transfer from ZnS host to Mn2+ impurity is also measured t o occur on the time scale of 700 ps.