A hexagonal-close-packed (hcp), hierarchical amorphous TiO2 nanocolumn array was fabricated by pulsed laser deposition (PLD) using a PS colloidal monolayer as a template under a high pressure (6.7 Pa) of background oxygen gas. The formation mechanism was investigated, and a model of multidirection glancing deposition was proposed to explain the formation process. This strategy can be extended to the fabrication of similar structures using different materials. Interestingly, this nanostructured array could be transferred to almost any substrate, avoiding restriction of substrate types in fabrication of nanocolumn arrays, which is helpful in the design and creation of nanodevices on various desired substrates. This hierarchical nanocolumn array exhibits excellent superamphiphilicity with both water and oil contact angles of 0 degrees, without further UV irradiation. More importantly, the amorphous TiO2 nanocolumn array demonstrates better performance in photocatalytic activity than an anatase nanocolumn array due to its large surface area and special microstructures, suggesting that the surface area of the TiO2 is preferable to its crystal structure for enhancing photocatalytic activity. The combination of superamphiphilicity and photocatalytic activity gives the surface an excellent self-cleaning effect.

ZnO nanoparticles were prepared by laser ablation of a zinc metal plate in a liquid environment using different surfactant (cationic, anionic, amphoteric, and nonionic) solutions. The nanoparticles were obtained in deionized water and in all surfactant solutions except the anionic surfactant solution. The average particle size and the standard deviation of particle size decreased with increasing amphoteric and nonionic surfactant concentrations. With the increase of the amphoteric surfactant concentration, the intensity of the defect emission caused by oxygen vacancies of ZnO rapidly decreased, while the exciton emission intensity increased. This indicates that anionic oxygen in the amphoteric surfactant molecules effectively occupied the oxygen vacancy sites at the ZnO nanoparticle surface due to charge matching with the positively charged ZnO nanoparticles.

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When a fluorescent compound shows unique optical properties, an elucidation of the mechanism may lead to an important development of novel sensing strategies. A helical 3,3′-di-tert-butylsalen-zinc(II) complex, [Zn 2 L 1 2 ], has a red-shifted fluorescence as compared to that of [ZnL 2 2 ], a half-structured mononuclear complex of [Zn 2 L 1 2 ]; in addition, [Zn 2 L 1 2 ] exhibits a fluorescence color change from green to light blue under external stimulations. We investigated the origins of these phenomena by spectroscopy, fluorescence lifetime measurement, fluorescence microscopy, X-ray powder diffraction, and X-ray singlecrystal analysis. From the experimental data, we concluded that intramolecular and intermolecular π-π interactions are critical elements that determine the shifts of the fluorescence to a longer wavelength.