The active sites in different TS-1 zeolites for propylene epoxidation studied by ultraviolet resonance Raman and ultraviolet visible absorption spectroscopies

The titanium species in four kinds of titanium-containing MFI zeolites have been studied by ultraviolet (UV)-Raman and ultraviolet visible (UV-Vis) absorption spectroscopies and by the epoxidation of propylene with diluted H2O2 solution (30%). UV-Raman spectroscopy is proved to be a suitable means to estimate qualitatively the framework titanium in TS-l zeolites. Based on the comparison of the relative intensity ratio I-1125/I-380 of UV-Raman spectra, the TS-1(conv.) sample synthesized hydrothermally by the conventional procedure shows the highest amount of framework titanium. UV-Vis spectroscopy reveals that besides minor anatase. titanium species are mainly tetrahydrally coordinated into the framework for TS-l(conv.) or the Ti-ZSM-5 sample prepared by gas-solid reaction between deboronated B-ZSM-5 and TiCl4 vapor at elevated temperatures. For the TS-1(org.) and TS-1(inorg.) samples synthesized hydrothermally using tetrapropylammonium bromide (TPABr) as template and tetrabutylorthotitanite (TBOT) and TiCl3 as titanium source, respectively, the presence of mononuclear and isolated TiOx species which are proposed to bond to the zeolite extraframework is observed. In addition to the framework titanium species, these isolated TiOx species are assumed to be also active for propylene epoxidation.

UV Raman spectroscopic study on the synthesis mechanism of zeolite X

The synthesis of zeolite X is characterized by UV Raman spectroscopy, NMR spectroscopy, and X-ray diffraction. UV Raman spectra of the liquid phase of the synthesis system indicate that AI(OH); species are incorporated into silicate species, and the polymeric silicate species are depolymerized into monomeric silicate species during the early stage of zeolite formation. An. intermediate species possessing Raman bands at 307, 503, 858 and 1020 cm(-1) is detected during the crystallization ill the solid phase transformation. The intermediate species is attributed to the beta cage, the secondary building unit of zeolite X. A model for the formation of zeolite X is proposed, which involves four-membered rings connecting to each other via six-membered ring to form beta cages, then the beta cages interconnect via double six-membered rings to form the framework of zeolite X. (C) 2001 Elsevier Science B.V. All rights reserved.

Characterization of aluminosilicate zeolites by UV Raman spectroscopy

A series of aluminosilicate zeolites are characterized by UV Raman spectroscopy for the first time, and UV Raman spectra of various zeolites give strong and clear bands with high resolution, while conventional Raman spectra of these zeolites are difficult to obtain because of a strong background fluorescence. Additionally, these zeolites show several new bands in UV Raman spectroscopy. A summary of these UV Raman spectra over various zeolites suggests that the bands at 470-530, 370-430, 290-410, and 220-280 cm(-1) can be assigned to the bending modes of 4-, 5-, 6-, and 8-membered rings of aluminosilicate zeolites, respectively. Furthermore, it is found that the band intensity of zeolites in UV Raman spectroscopy is dependent on the Si/Al ratio. Moreover, the UV Raman spectra of crystallization, for zeolite X at various times show that, in the initial stage of crystallization, the 4-membered rings (510 cm(-1)) interconnect each other to form beta -cages with 6-membered rings (390 cm(-1)), which further crystallize to zeolite X. (C) 2001 Elsevier Science B.V. All rights reserved.

Direct synthesis of highly ordered Fe-SBA-15 mesoporous materials under weak acidic conditions

Iron-substituted SBA-15 (Fe-SBA-15) materials have been synthesized via a simple direct hydrothermal method under weak acidic conditions. The powder X-ray diffraction (XRD), NZ sorption and transmission electron microscopy (TEM) characterizations show that the resultant materials have well-ordered hexagonal meso-structures. The diffused reflectance UV-vis and UV resonance Raman spectroscopy characterizations show that most of the iron ions exist as isolated framework species for calcined materials when the Fe/Si molar ratios are below 0.01 in the gel. The presence of iron species also has significant salt effects that can greatly improve the ordering of the mesoporous structure. Different iron species including isolated framework iron species, extraframework iron clusters and iron oxides are formed selectively by adjusting the pH values of the synthesis solutions and Fe/Si molar ratios. (c) 2005 Elsevier Inc. All rights reserved.

带电胶体粒子结晶过程的实验研究

利用带电单分散聚苯乙烯胶体粒子,通过自组装机理,制备了体积百分比为4·8%的具有多晶结构的胶体晶体,并用Kossel衍射技术和紫外可见分光光度计分别对晶体的生长过程进行了监测.通过对Kossel的图像分析检测不同阶段相应的晶格结构,发现胶体结晶过程晶体结构演变顺序为由液态—随机层结构—堆无序结构—面心立方孪晶结构到面心立方结构.定量地确定了结晶过程中晶体不同晶面的晶面间距和晶体的晶格常数,通过紫外可见分光光度计测量的晶体透射谱图,计算得到111晶面的晶面间距和晶体的晶格常数,与用Kossel衍射技术得到的结果相一致,还发现随样品放置时间的延长,衰减峰变窄和加深,并向短波方向移动,对应着晶体的晶格常数减小的现象.

石英波片偏光干涉谱的研究

根据石英晶体双折射率的色散特性,对石英波片的偏光干涉谱进行了理论分析和数值模拟,提出了一种石英波片延迟量和厚度的偏光干涉标定法。即由偏光干涉谱,可以得出石英波片在200～2000 nm宽光谱范围内的延迟量；通过对长波段的偏光干涉谱极值波长的精确判断,可以准确地计算出该石英波片的厚度。利用Lambda 900 紫外可见近红外分光光度计对一片石英波片的偏光干涉谱进行了测量。在波长精度为0.1 nm的情况下,测量的厚度精度为0.1 μm。误差分析结果表明,通过提高光谱的最小分辨力及选择较长的光谱波段进行测量计算

一种新型芴类衍生物的光谱性质研究

合成了具有大π共轭性的对称型芴类衍生物9，9-二（2-乙基已基）-2，7-（2-（4-甲氧基）苯-2，1-乙烯基）芴（简写为MO-F1u—MO）。通过元素分析、质谱、紫外-可见光谱和红外光谱对其进行了表征。测试了该染料在乙腈、二氯甲烷、四氢呋喃和正己烷4种不同极性溶剂中的线性吸收光谱和单光子荧光谱。结果发现溶剂效应对吸收光谱和荧光光谱表现出不同程度的影响，对产生这些光谱行为的主要原因进行了讨论。

Preparation, characterization and gas sensing properties of nickel octa-iso-pentyloxynaphthalocyanine spin-coating films

Spin-coated films of nickel 1,6,10,15,19,24,28,33-octa-iso-pentyloxy-2,3-naphthalocyanine complex were obtained and characterized by UV-vis absorption spectroscopy. A linear relationship between the absorbance and solution concentration was observed. Low concentration solutions could afford smooth and homogeneous film surfaces as indicated by atomic force microscopy. The film structure was studied by small angle X-ray diffraction. The films were used for NO2 sensing experiments. The results indicate that the elevation of sensing temperature can shorten the response time and increase recovery ratio and response magnitude of the sensing films. High NO2 concentration can also shorten response time. (C) 2008 Elsevier B.V. All rights reserved.

TeO2-Nb2O5-YF3玻璃系统的形成区及性质研究

制备了一种新型的氧卤碲酸盐玻璃：TeO2-Nb2O5-YF3,给出并研究了TeO2-Nb2O5-YF3三元系统的玻璃形成范围。测试了玻璃的密度、折射率、差热(DTA)、拉曼光谱、红外透射光谱以及紫外吸收光谱,通过光谱分析研究了组分含量的变化对玻璃结构及红外透射特性的影响。实验结果表明,TeO2-Nb2O5-YF3玻璃系统具有优良的成玻璃性能和热稳定性等特性,而且在2.8～3.3 μm区域内无明显的[OH]基团吸收,在中红外3～5 μm区域具有优良透射性能,因此在中红外透射方面具有潜在应用价值。

TeO2-ZnCl2-BaO-NaF玻璃系统的结构及中红外透过特性的研究

制备了一种新型的氧卤碲酸盐玻璃：（80-x）TeO2—15ZnCl2-xBaO-5NaF（x=30、20、10、0mol％），对玻璃的机械强度、热稳定性、拉曼光谱、紫外吸收光谱、红外透过光谱等特性进行了研究．通过拉曼光谱分析研究了玻璃组分含量的变化对玻璃结构和红外透过性能的影响．结果表明，随着BaO含量的增加，玻璃在红外波段透过率显著增加，并且红外透过截止波长向长波方向移动，本文对这一实验结果进行了机理性的研究探讨．同时，通过在熔制过程中通入高纯O2，以及引入适量的卤化物有效地除去玻璃中的[OH]基团，使

Effect of processing parameters on the optical properties of TiO2/ormosil planar waveguide

Hybrid TiO2/ormosil waveguiding films have been prepared by the sol-gel method at low thermal treatment temperature of 150° C. The influence of processing parameters including the molar ratios of titanium butoxide (Ti(OBu)(4))/3-glycidoxypropyltrimethoxysilane (GLYMO) and H2O/Ti(OBu)(4) (expressed as R), especially aging of sot on the optical properties was investigated. The optical properties of films were measured with scanning electron microscope (SEM), UV/VIS/NIR spectrophotometer (UV-Vis), m-line and the scattering-detection method. The results indicate that the film thickness increases with the increase of sol aging time, but the variation of refractive index as a function of sot aging time depends on the relative ratios of GLYMO to Ti(OBu)(4). Higher transmittance and lower attenuation of the planar waveguide can be obtained in the sol with lower Ti(OBu)(4) contents and shorter aging time.

Optical and surface properties of hybrid TiO2/ormosil planar waveguide prepared by the sol-gel process

Two kinds of silanes, 3-glycidoxypropyltrimethoxysilane (GLYMO) and 3-trimethoxysililpropylmethacrylate (TMSPM), were used to prepare ormosil waveguide films by the sol-gel method. Thirty percent Ti(OBu)(4) and 70% silane were contained in the precursor sets. The properties of films were measured by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV/VIS/NIR spectrophotometer (UV-vis), atomic force microscopy (AFM), m-line and scattering-detection method. The films from GLYMO and TMSPM precursors exhibit similar thickness (2.58 mu m for GLYMO, 2.51 mu m for TMSPM) and refractive index (1.5438 for GLYMO, 1.5392 for TMSPM, lambda=632.8 nm), but the film from TMSPM precursor has higher propagation loss (1.024 dB/cm, lambda=632.8 nm) than the film prepared from GLYMO (0.569 dB/cm, lambda=632.8 nm). Furthermore, the film prepared from TMSPM is easy to be opaque and cracks during coating whereas the same phenomenon was not found for the film prepared with GLYMO. It is confirmed that GLYMO is a better precursor than TMSPM for waveguide film preparation. (C) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Effect of water content in sol on optical properties of hybrid sol-gel derived TiO2/SiO2/ormosil film

Sol-gel derived TiO2/SiO2/ormosil hybrid planar waveguides have been deposited on soda-lime glass slides and silicon substrates, films were heat treated at 150 degreesC for 2 h or dried at room temperature. Different amounts of water were added to sols to study their impacts on microstructures and optical properties of films. The samples were characterized by m-line spectroscopy, Fourier transform infrared spectroscopy (FT-IR), UV/VIS/NIR spectrophotometer (UV-vis), atomic force microscopy (AFM), thermal analysis instrument and scattering-detection method. The refractive index was found to have the largest value at the molar ratio H2O/OR = 1 in sol (OR means -OCH3, -OC2H5 and -OC4H9 in the sol), whereas the thickest film appears at H2O/OR = 1/2. The rms surface roughness of all the films is lower than 1.1 nm, and increases with the increase of water content in sol. Higher water content leads to higher attenuation of film. (C) 2004 Elsevier B.V. All rights reserved.

Preparation and characterization of hybrid ZnO/ormosils films

Hybrid ZnO/ormosils Elms are prepared by the sol-gel method. A FT-IR spectrometer, 900 UV/VIS/NIR spectrophotometer, atomic force microscope, and ellipsometer are employed to investigate microstructure and optical properties of the films fired at different temperatures. The results show that the films with high transmittance and low surface roughness could be obtained at the heat-treatment temperature of 150 degrees C, the refractive index and thickness of the film are 1.413, 2.11 mu m, respectively. Higher temperatures (350 degrees C, 550 degrees C) change the Elm microstructure severely, and then decrease the transmittance of the films.

熔制条件对铋酸盐玻璃性质的影响

采用传统的玻璃熔融法制备了组成为60Bi2O3-20B2O3-15SiO2-5La2O3(mol%)的铋酸盐玻璃， 系统研究了不同工艺过程对玻璃性能的影响. 分析了样品ICP的成分，扫描电镜，X-射线衍射谱， 差热分析和紫外-可见-近红外透过光谱测试. 结果表明：使用刚玉坩埚能提高玻璃的抗析晶稳定性 和透过率，陶瓷坩埚和白金坩埚均受到严重腐蚀，玻璃组分也随之发生很大变化. 当熔制温度从1 100 ℃变化到1 300 ℃时，玻璃的颜色从浅黄色变到深红棕色. 尤其是白金粒子被腐蚀进入玻璃液 后，玻璃中很容易形成纳米颗粒或者团聚形成胶体粒子，在玻璃中形成色散源，加深玻璃的颜色， 降低透过率. 1 300 ℃下，白金粒子起到晶核剂的作用，生成Bi2Pt2O7和BiB3O6晶相，导致玻璃失透.