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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 presents study on power-dependent photocatalytic activity of zinc oxide (ZnO). It mentions photocatalytic activity of ZnO investigated using laser pulses for dye molecule rhodamine 101. It adds emission was collected using an optical lens, spectrally resolved using a monochromator, and detected using a photomultiplier.

Photocurrent of a single ZnO nanowire synthesized by a sol-gel route was investigated. In vacuum, the dark current was bigger but the photoresponse was slower than that in air, attributed to the release of the available charge carriers by the desorption of water molecules and the decrease of the exchange rates of molecular ions. Under the steady radiation of the ultraviolet light (λ=325 nm), a gradual decrease of the photocurrent was noticeable, which can be explained in terms of the annihilation of the carriers by the replacement of hydroxyl groups (OH-) by O2-, resulting in the decrease of charge carriers. [ABSTRACT FROM AUTHOR]

The article discusses the observation of polarization of lasing in Zinc oxide (ZnO) nanowires focusing on the hexagonal cross shown by ZnO nanowires and unusual lasing peaks that overlap the transverse mode. Topics include photoluminescence spectrum shown by ZnO nanowires, figures showing ZnO nanowires lying on the substrate, and lasing peaks that are obtained at fine angles.

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]

The article discusses the observation of polarization of lasing in Zinc oxide (ZnO) nanowires focusing on the hexagonal cross shown by ZnO nanowires and unusual lasing peaks that overlap the transverse mode. Topics include photoluminescence spectrum shown by ZnO nanowires, figures showing ZnO nanowires lying on the substrate, and lasing peaks that are obtained at fine angles.

Abstract: Zinc oxide (ZnO) nanoparticles were prepared in neat deionized water by laser ablation with various ablation times (10–40min), fluences (50–130mJ/pulse), and wavelengths (1064, 532, and 355nm). The size and shape of the nanoparticles were affected only slightly by the ablation time and fluence at a wavelength of 1064nm, which was explained by a dynamic formation mechanism with surface charge effects. The nanoparticles formed by ablation at 355nm had a distinctive wire-shape with a small diameter, which was attributed to a continuous fragmentation and formation mechanism. [Copyright &y& Elsevier]

Abstract: Optical properties of zinc oxide (ZnO) nanoparticles prepared in supercritical methanol and supercritical water were investigated. Interstitial zinc and oxygen vacancy were the major defects in the ZnO nanoparticles synthesized in supercritical methanol. The addition of oleic acid as a surface modifier resulted in the isolation of the nanoparticles and the removal of interstitial zinc. Lasing was observed with sharp longitudinal modes and a superlinear increase in the emission intensity of the ZnO nanowires synthesized in supercritical water. The band gap renormalization due to the electron–hole plasma induced a red-shift in the emission band, whereas the individual longitudinal modes were blue-shifted due to a change in refractive index. [Copyright &y& Elsevier]