Propagation of Laguerre–Gaussian beams in cubic–quintic nonlinear media by variational approach

We analyze the propagation of Laguerre–Gaussian (LG) beams in a cubic–quintic nonlinear medium by using the variational method. For low intensities, the results are in good agreement with the results of a numerical simulation. The characteristics of LG beams in the nonlinear medium are explored and the electric field distribution in the far field after passing through the nonlinear medium is calculated.     

Structural,optical and photocatalytic properties of (Mg,Al)-codoped ZnO powders prepared by sol–gel method

Structural and optical properties of 1 at % Al-doped Zn_1−xMg_xO (x=0–8%) powders prepared by sol–gel method were systematically investigated by means of X-ray diffraction, scanning electron microscopy, ultraviolet–visible absorbance measurement, photoluminescence and Raman scattering spectra. All the powders retained the hexagonal wurtzite structure of ZnO. The band gap and near band emission energies determined from absorbance and photoluminescence spectra increased linearly with increasing Mg content, respectively, which implied that the Mg worked effectively on ZnO band gap engineering, irrespective of Al codoping. However, according to the PL and Raman scattering studies, for the sample of x=8%, the Al doping efficiency was decreased by higher Mg codoping. On the other hand, the effect of Mg codoping on photocatalytic degradation of methylene orange was explored experimentally. The substitution of Mg ions at Zn sites shifted the conduction band toward higher energies and then enhanced the photocatalytic activity, while the incorporation of interstitial Mg ions and decreased Al doping efficiency for higher Mg doping sample (x=8%) reduced the photocatalytic activity.     

增强光催化活性的3D分级结构Bi2W06微球及表面酸性

以KNO3为矿化剂,用水热法制备了3D分级结构Bi2WO6微球,通过XRD、SEM、BET对产物进行了表征．探讨了3D分级结构Bi2WO6微球可能的形成机理．以罗丹明B为模型污染物,研究了合成产物的光催化性质．结果表明：在紫外光下,RhB的降解以共轭结构断裂的光催化反应为主;而在可见光照射下,RhB的降解可能是光催化和光敏化共同作用的结果．进一步以吡啶为探针分子,通过吸附吡啶红外光谱探讨了Bi2W06表面酸性与光催化降解RhB之间的关系．研究显示,Bi2W06具有较强的表面酸性,增强了Bi2WO6与RhB分子之间吸附作用,有利于染料分子上的电子跃迁至催化剂上,易于发生光敏化和光催化反应。     

红外光谱电化学法研究对苯二酚的电化学氧化还原过程

利用现场红外光谱电化学、循环伏吸、导数循环伏吸法及其重构的电流-电位(i-E)曲线,研究对苯二酚(QH2)在不同溶剂中的电化学行为,得到可能的氧化还原机理。结果表明,在乙腈和中性非缓冲溶液中,QH2氧化终产物是对苯醌(Q)。在中性非缓冲溶液的还原的过程中,一部分Q在较正的电位下还原成QH2,另一部分Q在较负的电位下还原成Q2"。碱性溶液中,当加入1倍QH2量的OH-,循环伏安图(CV)出现2个电流相当的氧化峰(Q2",QH2);加入2倍OH-后,只出现一对氧化还原峰(Q2"/Q),从红外谱图上可清晰观察到电化学过程中氢键的变化。     

Synthesis and Crystal Structure of Novel Mixed-metal Alkoxide Clusters of Ytterbium and Sodium: Yb4O4（OiPr）16Na12

The mixed-metal cluster Yb4O4(OiPr)16Na12 has been synthesized and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. The crystal belongs to the cubic system, space group P23 with a = b = c = 13.9788(3), V = 2731.55(10)3 , Z = 1, Dc = 1.202 g/cm 3 , Mr = 1977.42, = 3.480 mm-1 , F(000) = 972, the final R = 0.0288 and wR = 0.1511 for 1677 observed reflections with Ⅰ > 2σ(Ⅰ). X-ray analysis reveals that Yb4O4 (OiPr)16Na12 is centrosym-metric and the structure contains four ytterbium metals and twelve sodium metals, and each ytterbium atom is coordinated by six oxygen atoms. In addition, an ancillary computational analysis of the optimized molecular unit was provided. The large energy gap (3.31 eV) between HOMO and LUMO indicates that the structure framework is particularly stable.     

Synthesis,Characterization, and Crystal Structure of One Novel Indolo[3,2-b]carbazole Derivative

Indolocarbazole derivatives have been reported to be promising organic semicon- ductor candidates and electroluminescent （EL） materials. One novel indolocarbazole derivative, 2,8-acetyl-5,11-dihexyl-6,12-（di-p-tolyl）-5,11-indolo[3,2-b]carbazole （YK4）, has been synthesized, and its crystal structure has also been carefully studied. YK4 is triclinic, space groups Pi with a = 9.409（5）, b = 13.974（5）, c = 15.488（5） A, α = 90.281（5）, β = 105.456（5）, Z= 93.728（5）°, M,. = 688.94, V= 1958.1（14） A3, Z = 2, Dc.= 1.168 g/cm-3,μ = 0.070 mm-1, F（000） = 740, Rint = 0.0475, R （I〉 20（/）） = 0.1146, wR （I〉 20（/）） = 0.2186, R（all data） = 0.2192 and wR （all data） = 0.2701. Like other indolo[3, 2-b]carbazole derivatives which were introduced in the 5- and 11-positions, the intermolecular short contacts are localized between the pendant groups and acetyl groups of the neighboring indolocarbazole molecules. The molecule of YK4 possesses poor face-to-face π-π stacking between two adjacent molecules in the crystal. The calculated bond lengths and bond angles of YK4 also proved the result of crystallography.     

磁性SiO2/PSt中空复合微球的细乳液法制备及表征

采用双原位细乳液聚合工艺,将疏水改性的磁性纳米粒子(MNP)加入到细乳液反应体系的油相中,利用增长的聚合物和单体TEOS之间的相分离原理,实现了聚合物的生成和TEOS的水解缩合同步进行,一步获得了磁性SiO2/PSt中空复合微球.通过红外光谱(FTIR)、透射电镜(TEM)、热重差热分析(TGA/DSC)和振动磁强计(VSM)对中空复合微球进行了表征.结果表明,制备的SiO2/PSt中空复合微球的尺寸范围为300～600 nm,当加入磁性纳米粒子后,得到的磁性SiO2/PSt中空微球保持了原来的中空结构,中空复合微球内腔的大小可以通过改变单体TEOS的加入量来控制.SiO2/PSt中空微球对磁性纳米粒子的包封率达到了86%.磁性SiO2/PSt中空复合微球具有超顺磁性,饱和磁强度值为14.7 emu/g.     

Preparation and photoelectrochemical performance of PbSe/BaTiO3/TiO2 composite film

By dipping-lifting in sol–gel solution and reducing process, the TiO₂ composite film on the glass plate was first prepared. Then, the PbSe/BaTiO₃/TiO₂ composite film was fabricated by interface reaction with BaTiO₃ and PbSe on the surface of TiO₂ composite film. The characterization results show that the uniform porous TiO₂ film is made up of the anatase crystal, and the PbSe/BaTiO₃/TiO₂ composite film is constructed by doping or depositing BaTiO₃ and PbSe nanoparticles on the surface of TiO₂ film. The photoelectrochemical measurement results indicate that the PbSe/BaTiO₃/TiO₂ composite film has an interesting photoelectrochemical conversion property.     

Generation of a four-qubit cluster state for atoms in a thermal cavity

We propose two schemes for generating a four-atom cluster state in a thermal cavity. With the assistant of a strong classical field the photon-number-dependent parts in the effective Hamiltonian are canceled. Thus the schemes are insensitive to the thermal field. The schemes can also be used to generate the cluster state for the trapped ions in thermal motion.