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ZnO nanoparticles with different shapes and sizes were prepared by changing coordinating ligands. Hexagonal cones presented UV and green (∼500 nm) emissions, which originated from excitons and defects, respectively. Oxygen vacancies were found to be major defects in the hexagonal cones. Blue emission at ∼440 nm was observed for hexagonal plates, and analyses of time-resolved photoluminescence spectra showed that two transitions were responsible for this blue emission, because transitions from Zni to the valence band (430 nm) and from Zni to VZn (480 nm) were distinguished by emission wavelengths and lifetimes. The visible emissions from defects were related to the roles of coordinating ligands. [ABSTRACT FROM AUTHOR]

The article discusses the research which examines the electronic transitions of gold (Au) to perceive the photoluminescence spectrum of gold nanoclusters. Topics discussed include the photoluminescence of gold nanoclusters, the use of the Stokes shift to calculate the absorption spectrum of the observed emission spectrum, and the optimization of the geometries of gold in aqueous solution.

Er-doped SiOx thin films were fabricated by laser ablation of a Si:Er2O3 target in He atmosphere. We have measured the photoluminescence (PL) at 1.54 μm for the films grown at different He pressures and found that the oxygen density of the grown film that strongly influences the PL intensity is highly correlated with the ambient He pressure. This manifests that oxygen density of the film can be controlled in an inert atmosphere to maximize PL intensity when we adopt pulsed laser deposition (PLD) technique to deposit Er-doped SiOx thin films. Also, we have examined the temperature dependence of PL and observed that the thermal quenching is greatly reduced for the PLD-grown films. [Copyright &y& Elsevier]

Ordered arrays of Er-doped Si nanodots were fabricated by pulsed laser deposition using an anodic aluminum oxide (AAO) nanopore membrane. Er-doped Si (Si:Er) nanodots with an average diameter of 60–80 nm and a periodicity of 100 nm were uniformly assembled into hexagonally ordered nanopores of AAO membrane. Photoluminescence (PL) spectra taken from Si:Er nanodots showed an emission peak at 1.54 μm, which is due to intra-4f shell transition (4I13/2→4I15/2) of Er3+ ions. Postannealing of nanodot arrays up to 500 °C resulted in the enhancement of PL intensities without enlargement or aggregation of the nanodots. [ABSTRACT FROM AUTHOR]

Abstract: Photoluminescence (PL) of zinc oxide (ZnO) nanorods with an average thickness of 5nm and a length of 30nm is blue-shifted compared to the bulk due to quantum confinement effects. The exciton states remain relatively stable at a high carrier density due to a smaller exciton size and an enhanced exciton binding energy in the quantum confined nanorods, whereas the electron-hole plasma states are formed in the bulk at the similar carrier density. A linear dependence of the PL intensity on the excitation intensity also corroborates the assumption that the stable exciton states are responsible for the undisturbed emission at a high carrier density. [Copyright &y& Elsevier]

Abstract: Antimony (Sb) doping of SnO2 nanowires (NWs) was investigated for its optical and electrical effects. The low-temperature photoluminescence spectra of SnO2 NWs varied significantly with increasing Sb content, where the temperature-dependence of the visible emission at ca. 400nm was distinctive with Sb-doping, indicating different defect states, such as neutral and positively charged oxygen vacancies. Field effect transistors (FETs) with low-level Sb-doped SnO2 NW channels exhibited higher mobility, charge concentration, and faster response and recovery to UV light than intrinsic SnO2 NW FETs. [Copyright &y& Elsevier]

Abstract: Mg-doped ZnO thin films were fabricated by laser ablation of Zn:Mg targets consisting of Mg metallic strips and Zn disk in oxygen atmosphere with a goal to facilitate convenient control of Mg contents in the films. The characteristics of the deposited films were examined by analyzing their photoluminescence (PL), X-ray diffraction and X-ray photoelectron spectroscopy (XPS) spectra. Mg contents as analyzed by XPS indicate that the target composition is fairly transferred to the deposited films. The wurtzite structure of ZnO was conserved even for the highly doped ZnO films and there was no Mg- or MgO-related XRD peaks. With increase in the Mg content, the bandgap and PL peak energy shifted to blue and the Stokes shift became larger. [Copyright &y& Elsevier]