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At atmospheric pressure, anatase TiO2 films with various nano-morphologies have been grown on quartz substrate by non-thermal TiCl4-O[sub 2]-Ar reactive plasma vapor deposition. High concentration of oxygen vacancies and undercoordinated Ti atoms are incorporated into the crystal lattice of the deposited films, which can be tuned by changing the discharge conditions such as temperature and vapor flow rate. Strong visible luminescence is found for the deposited films, originating from the radiative recombination of trapped electrons due to uncoordinated Ti atoms and oxygen vacancies. To clarify the growth mechanism, an analytical model is proposed to explain the corresponding discharging process. We find the theoretical predictions agree well with experimental results. By effectively adjusting the morphology and lattice crystallinity, we believe this work can provide an expedient and controllable way to fabricate anatase films with interesting optical properties, which can meet the demands of complex practical situations to the maximum degree. [ABSTRACT FROM AUTHOR]

Cultivation of rice in unsaturated soils covered with mulch is receiving more attention in China because of increasingly serious water shortage; however, greenhouse gas emission from this cultivation system is still poorly understood. A field experiment was conducted in 2001 to compare nitrous oxide (N 2O) and methane (CH 4) emission from rice cultivated in unsaturated soil covered with plastic or straw mulch and the traditional waterlogged production system. Trace gas fluxes from the soil were measured weekly throughout the entire growth period using a closed chamber method. Nitrous oxide emissions from unsaturated rice fields were large and varied considerably during the rice season. They were significantly affected by N fertilizer application rate. In contrast, N 2O emission from the waterlogged system was very low with a maximum of 0.28 mg N 2O m -2 h -1. However, CH 4 emission from the waterlogged system was significantly higher than from the unsaturated system, with a maximum emission rate of 5.01 mg CH 4 m -2 h -1. Our results suggested that unsaturated rice cultivation with straw mulch reduce greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

We propose and study a kind of bilayered chiral metasurface (BCM) composed of complementary L-shaped resonators with a lossless dielectric spacer that can realize linear polarization rotation with ultrahigh conversion efficiency. We present a theoretical analysis of the BCM with specific chiral geometry that enables asymmetric transmission for linear polarization only. Numerical results show that the proposed metasurface has dual-band asymmetric transmission with nearly 100% cross-polarization conversion efficiency when the loss is ignored. More importantly, depending on the incident direction, only one of the cross-polarization transmissions can approach unity while all the remaining transmissions are close to zero. As a result, nearly perfect linear polarization rotation is achieved for a particular polarization direction. We further show that the working frequency and the bandwidth of the proposed BCM can be tuned by adjusting the geometric size and spatial arrangement of the unit cell. [ABSTRACT FROM AUTHOR]