title: Emission properties of manganese-doped ZnS nanocrystals.
abstract: We have performed steady-state and time-resolved fluorescence studies on undoped and Mn-doped ZnS nanocrystals with approximately 16 A diameter. While there is no band-edge emission, the intensity of the steady-state blue fluorescence from ZnS surface states decreases upon Mn incorporation, which gives rise to an orange emission. These results show that Mn incorporation competes very effectively with the donor-acceptor surface states for the energy transfer from the electron-hole pair excited across the band gap. In both undoped and doped samples, the time-resolved fluorescence studies establish the presence of a distribution of decay lifetimes possibly due to a number of emission centers in the nanocrystals. A faster short-time decay of the blue emission in the Mn-doped samples compared to that in the undoped sample suggests an additional decay channel for the surface states via an energy transfer from these states to the dopant levels.
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India. sarma@sscu.iisc.ernet.in
authors.forename: Sameer
authors.initials: S
authors.lastname: Sapra
authors.forename: Ankita
authors.initials: A
authors.lastname: Prakash
authors.forename: Ajit
authors.initials: A
authors.lastname: Ghangrekar
authors.forename: N
authors.initials: N
authors.lastname: Periasamy
authors.forename: D D
authors.initials: DD
authors.lastname: Sarma