No abstract

The oxidation power of the TiO2 - x N x powders with low nitrogen concentrations (<0.02) was evaluated by the decomposition of gaseous 2-propanol (IPA) under the same absorbed photon number, 1.4 × 1014 quanta·cm-2·s-1, of visible (Vis) or ultraviolet (UV) light. Regardless of the x value, the quantum yield values from irradiating with Vis light was lower than with UV light, which suggests that the isolated narrow band formed above the valence band is responsible for the Vis light response in the present nitrogen doped TiO2. In addition, increasing the nitrogen concentration when irradiating with UV light lowered the quantum yields, indicating that the doping sites could also serve as recombination sites.

Photoinduced magnetization was observed in a Prussian blue analog, K0.2Co1.4- [Fe(CN)6]·6.9H2O. An increase in the critical temperature from 16 to 19 kelvin was observed as a result of red light illumination. Moreover, the magnetization in the ferrimagnetic region below 16 kelvin was substantially increased after illumination and could be restored almost to its original level by thermal treatment. These effects are thought to be caused by an internal photochemical redox reaction. Furthermore, blue light illumination could be used to partly remove the enhancement of the magnetization. Such control over magnetic properties by optical stimuli may have application in magneto-optical devices.

Hydrophobicity and sliding behavior of water droplets were investigated on various hydrophobic pillarlike and groove structures prepared on a silicon wafer by dicing and subsequently coating with fluoroalkylsilane. The dominant hydrophobicity mode was changed from Wenzel's mode to Cassie's mode at a smaller roughness than that expected from the calculation based on the sinusoidal surface by Johnson and Dettre. The effect of water intrusion on the microstructure due to droplet weight was revealed to be an important factor governing the water sliding angle on the surface. In a comparison of the sliding behavior of water droplets over pillarlike and groove structures, it was demonstrated that a proper design of the surface with respect to shape and extent of the three-phase line is more effective than the increase of contact angles merely by decreasing the solid−water contact area.