Fabrication and Wettability of ZnO Nanorod Array

ZnO nanorod arrays were prepared in an open system by using a simple aqueous solution method. Spindlelike, wimble-like, tower-like and hexagonal rod-like ZnO rods were obtained under different conditions. ZnO nanorod arrays with different morphology and size were studied by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and contact angle measurement （CAM）. The size of ordered zinc oxide rods can be controlled by temperature of water bath, because this temperature can influences growing speeds in different crystal directions. Some additives, such as urea and thiourea, were introduced into reaction solution to improve quality of arrays. Surface character of ZnO nanorod arrays can be changed from hydrophilic to hydrophobic, which was proved to be dependence on size of air grooves on surface.

The molecular structure and the analytical potential energy function of S2^- and S3^-

In this paper, the equilibrium geometry, harmonic frequency and dissociation energy of S2^- and S3^- have been calculated at QCISD/6-311＋＋G（3d2f） and B3P86/6-311＋＋G（3d2f） level. The S2^- ground state is of 2IIg, the S3^- ground state is of 2B1 and S3^- has a bent （C2v） structure with an angle of 115.65° The results are in good agreement with these reported in other literature. For S3^- ion, the vibration frequencies and the force constants have also been calculated. Base on the general principles of microscopic reversibility, the dissociation limits has been deduced. The Murrell-Sorbie potential energy function for S2^- has been derived according to the ab initio data through the least- squares fitting. The force constants and spectroscopic data for S2^- have been calculated, then compared with other theoretical data. The analytical potential energy function of S3^- have been obtained based on the many-body expansion theory. The structure and energy can correctly reappear on the potential surface.

Towards the understanding of 1^1 p1 meson mass spectrum

Based on the meson-meson mixing and Regge trajectory, this paper establishes the mass relations which can describe the mass spectrum of 1^1 P1 meson state. Using these mass relations, it obtains the mass of K1B, hi （1380） and hc（1P） to be 1358.5MeV, 1468 MeV and 3543.9 MeV, respectively. The results are compared with other theoretical results and should be tested by experiments in the future.

Enhanced Photocatalytic Activity of ZnO/CuO Nanocomposites Synthesized by Hydrothermal Method

In this paper, we have demonstrated a facile and low-cost synthesis of the ZnO/CuO nanocomposites by two-step hydrothermal methods. The photocatalytic properties of the as-synthesized ZnO/CuO nanocomposites have been evaluated by the photodegradation of methylene blue(MB) and methyleneorange(MO) under UV irradiation. Experimental results show that MB and MO can be degraded completely within 15 and 25 min by the ZnO/CuO nanocomposites and its photodegradation rate is 6 times faster than that of pure ZnO. This enhanced photocatalytic activity can be ascribed to the low recombination probability of photo-induced carriers due to the efficient charge transfer in the nanocomposites. The as-synthesized ZnO/CuO nanocomposite may be a promising candidate for dye photodegradation of wastewaters.

Effect of mixing process on the luminescent properties of SrAl_2O_4:Eu^(2+),Dy^(3+) long afterglow phosphors

A new mixing method was developed for solid-state reaction synthesis of SrAl2O4:Eu2+,Dy3+ long afterglow phosphors.The morphology and crystal structure of the phosphors were analyzed with scanning electron microscope(SEM) and X-ray diffractometer(XRD).The excitation and emission spectra of the long afterglow phosphors were measured,and the main emission band was around 514 nm.The decay time of the product was measured and compared with the phosphors prepared using dry-mixing method and wet-mixing method.It ...

On the mass of the ss^- member of the 1^3D1 meson nonet

In the framework of Regge phenomenology and meson meson mixing, this paper estimates the mass of isoscalar state （ss^-） of the 1^3D1 meson nonet, and the results given by two different approaches are 1735.51 ± 59MeV and 1730.29 ±46.SMeV.

The mass of the isodoublet of the 2^1S0 meson nonet revisited

In the qq quark model, the states π（1300）, η（1295） and η（1475） are assigned as the 2^1S0 meson nonet. The mass of the isodoublet remains interesting and needs further confirmation in experiments. This paper employs the phenomenological trajectory on the （N, M^2）-plot and meson meson mixing methods to calculate the mass of this state, the calculated results are 1341 MeV and 1311.58 ± 59 MeV respectively. These predictions can be compared with experiments in the future.

Assignment of Isodoublet of 2^3S1 Meson Nonet

Inserting the masses of some states, which have been established in the experiments or the theory of lattice QCD, we investigate the mass of the isodoublet of the 2^3S1 meson nonet. The agreement results, 1567 ± 22.6 MeV and 1576.8 MeV, are given by two different approaches. We suggest that the assignment of 2^3S1 meson nonet should be re-examined in future experiments.

Influence of Finite Chemical Potential on Critical Boson Mass in QED3

Using the coupled Dyson-Schwinger equation for the fermion propagator at finite chemical potential μ, we investigate the fermion chiral condensate when the gauge boson mass is nonzero in QED3. We show that the chiral symmetry restores when the boson mass is large enough, and the critical boson mass depends little on μ.

Photometric Monitoring of ROSAT-Selected Weak Line T Tauri Stars

We monitored the light curves of 22 weak-line T Tauri stars （WTTSs） discovered among the X-ray sources in the field of the Taurus-Auriga cloud. For 12 of the 22 WTTSs photometric periodic variability is confirmed and their rational periods are determined using Phase Dispersion Minimization （PDM） and Fourier analysis. Most of them are found to have periods shorter than one day. This gives further evidence for the spin up of solar-type stars predicted by the models of angular momentum evolution of pre-main sequence stars.

The Partner of f_(4)(2050)in the 1^(3)F_(4) Meson Nonet

The assignment of the 1^(3)F_(4) meson nonet is phenomenologically analyzed in the framework of Regge phenomenology and meson-meson mixing.The mass of the partner of in the 1^(3)F_(4) meson nonet is determined to be 2167±27 MeV.The quarkonia content and the decay properties of the two isoscalar states of the 1^(3)F_(4) meson nonet are presented.The predictions can be tested by the BES-Ⅲ experiment in the near future.

Rotation Periods of Nine ROSAT Selected Solar-Type Stars

We monitored 16 X-ray selected young solar-type stars for light variation and found appreciable periodic light variability with amplitudes of a few hundredths of a magni- tude in nine of the objects. Using the method of Phase Dispersion Minimization （PDM） and Fourier analysis （software PERIOD04）, the rotation periods of these stars were determined from the photometric data. The rotation periods of all nine stars are shorter than about 3 days. It is suggested that, as with the Pleiades cluster, small amplitude light variations are quite common among young solar-type stars with rotation periods around 3 days or less. This gives further evidence for the spin up of solar-type stars predicted by models of angular momentum evolution of pre-main sequence stars.

Partner of η2（1645） in the 11D2 Meson Nonet

In the qq quark model, the states π2（1670） and η2（1645） are assigned as the I1D2 meson nonet. The partner of state η2（1645） needs further confirmation in the experiments. We employ the meson-meson mixing and the Regge trajectory methods to calculate the mass of the partner of state η2 （1645） to be 1879.8 MeV and 1863 ± 24 MeV respectively. We also calculate the strong decay width in the 3po decay model. These predictions can be compared with experiments in the future.

Photocatalytic Properties of TiO2/Si-NPA Nano Composite Systems

A new composite system is fabricated by depositing the TiO2 film on a silicon nanoporous pillar array （Si-NPA） and annealing at 500℃ using the spin coating method. Such a composite system exhibits a uniform morphology with the micron-dimension pillar array. Photocatalytic properties are investigated based on the degradation of methyl orange dye solution, and the results show that the photocatalytic efficiency of such a nano-composite system is 1.7 times that of the TiO2/glass system. The enhancement of photocatalytic efficiency is attributed to the large surface area of the TiO2/Si-NPA system.

Growth and interface of amorphous La_2Hf_2O_7/Si thin film

Amorphous La2Hf2O7 thin films were deposited on Si（100） substrate by pulsed laser deposition （PLD） method under different con-ditions. The interfacial states of the La2Hf2O7/Si films were studied by synchrotron X-ray reflectivity （XRR） and X-ray photoelectron spec-troscopy （XPS）. When grown under vacuum condition, silicate, silicide and few SiOx were formed in the interface layer. However, the Hf-silicide formation could be effectively eliminated by the ambient oxygen pressure during film growth. The result revealed that the La2Hf2O7/Si interlayer was intimately related with growth condition. Insufficient supply of oxygen would cause Hf-silicide formation at the interface and it could be most effectively controlled by the ambient oxygen pressure during film growth.

Microstructure and properties of Sm-substituted BiFeO_3 ceramics

Bi1-xSmxFeO3 （x=0.00-0.15） ceramics were synthesized by sol-gel technique with rapid liquid phase sintering process to study the effects of samarium （Sm） substitution on their microstructure and properties. X-ray diffraction （XRD） and Raman studies showed that the structure of BiFeO3 was changed from rhombohedral to orthorhombic at the samarium substitution concentration about x=0.10. The SEM investigation suggested that the Sm substitution hindered the grain growth. Magnetic measurements showed that all the samples studied had a weak ferromagnetism, and the ferromagnetic property of BiFeO3 was improved by Sm substitution due to the suppressed or broken cycloid spin structure caused by the changes in the crystalline structure and size effect. The leakage current was found to be reduced with increasing Sm concentration. The dielectric and ferroelectric measurements showed that dielectric constant, dielectric loss and ferroelectric properties were strongly dependent on the Sm content, Sm substitution could significantly improve the dielectric constant, remnant polarization and decrease the dielectric loss due to the significant decrease of the electric leakage of the samples.

High Response in aTellurium-Supersaturated Silicon Photodiode

Single crystalline silicon supersaturated with tellurium are formed by ion implantation followed by excimer nanosecond pulsed laser melting(PLM).The lattice damaged by ion implantation is restored during the PLM process,and dopants are effectively activated.The hyperdoped layer exhibits high and broad optical absorption from 400 to 2500 nm.The n^(+)p photodiodes fabricated from these materials show high response(6.9 A/W at 1000 nm)with reverse bias 12 V at room temperature.The corresponding cut-off wavelength is 1258 nm.The amount of gain and extended cut-off wavelength both increase with increasing reverse bias voltage;above 100%external quantum efficiency is observed even at a reverse bias of 1 V.The cut-off wavelength with 0 V bias is shorter than the commercial silicon detector.This implies that the Burstein-Moss shift is due to hyperdoping.The amount of the extended cut-off wavelength increases with increasing reverse bias voltage,suggesting existence of the Franz–Keldysh effect.

Band offsets between amorphous La_2Hf_2O_7 and silicon

Abstract： Amorphous LazHf2O7 films were grown on Si（100） by pulsed laser deposition method. The valence and conduction band offsets between amorphous La2Hf2O7 film and silicon were determined by using synchrotron radiation photoemission spectroscopy. The energy band gap of amorphous La2Hf2O7 film was measured from the energy-loss spectra of O ls photoelectrons. The band gap of amorphous LazHf2O7 film was determined to be 5.4±0.2 eV. The valence and the conduction-band offsets of amorphous La2Hf2O7 film to Si were obtained to be 2.7±0.2 and 1.6±0.2 eV, respectively. These results indieated that the amorphous La2Hf2O7 film could be one promising candidate for high-k gate dielectrics.

Local structure of oxygen-deficient Yttrium oxide

Yttrium oxide thin films have been deposited on Si （100） substrate by using pulsed laser deposition （PLD） method. X-ray diffraction （XRD）, hard and soft X-ray absorption spectroscopy （XAFS） are employed to investigate the origin of oxygen vacancies and their influence on the structure and atomic distributions. The XRD results indicate that the Y203 thin films strongly orient the （111） axis of the cubic structure. Analyses on the Y K-edge extended X-ray absorption fine structures reveal that the coordination number of Y atoms decreases and the bond length of Y-O contracts due to the loss of oxygen atoms. The X-ray absorption near edge structure analysis together with a theoretical approach further confirms the oxygen vacancies formation and their possible location.