同步扫描—固体基质室温磷光法同时测定痕量对位三联苯和间位…

本文提出了一种新的测定间三联苯和对三联苯的同步扫描－ＳＳ－ＲＴＰ法。固体基质选用慢速定量滤纸，重原子盐为ＴＬ２ＳＯ４。以激发单色器和发射单色器的波长差Δλ＝１８０ｎｍ进行同步扫描，其同步特征峰间三联苯为４５０ｎｍ，对三联苯为４９０ｎｍ（均指发射波长）。间三联苯可直接由该特征峰的高度进行定量测定。对三联苯在４９０ｎｍ处的特征峰略受间三苯同步拖尾的影响，其峰值信号需加校正，间三联苯和对三联苯的线性范围     

微波辐射下苯偶姻合成苯偶酰的反应

研究了以乙酸铜、硝酸铵为氧化剂,在微波条件下,用400W的功率,15min即可获得很高的苯偶酰产率(85.8%),是一种有效的苯偶姻氧化反应新方法。     

离子液体催化苯与环己烯的Friedel-Crafts烷基化反应

室温离子液体是由特定的阳离子和阴离子构成,具有独特的性质和功能。将路易斯酸型离子液体应用于苯和环己烯的烷基化反应,考察了苯与环己烯摩尔比、反应温度、反应时间对烷基化反应产物收率的影响。结果表明以制备的咪唑盐离子液体为催化剂,在反应温度80℃、反应时间1.0h、苯烯摩尔比8：1的条件下,所得环己基苯的产物收率最高,为86.75%。离子液体可重复使用,活性基本没有降低。     

对苯蒸汽灵敏的光纤传感器

利用SnO_2薄膜设计了一种对苯蒸汽灵敏的光纤传感器,灵敏范围为0—700ppm,灵敏度达5ppm。并研究了SnO_2∶ZnO膜及SnO_2∶Ti膜对苯蒸汽的气敏光学性能。解释了气敏光学机理。     

Temperature Dependence of Photoinduced Birefringence in an Azobenzene Polymer

The photoinduced birefringence in an azobenzene polymer is investigated at different temperatures between -20℃ to 50℃. It is found that there is a peak value of photoinduced birefringence in the temperature dependence of the photoinduced birefringence under a certain pumping intensity. With the pump light in 90mW/cm^2, the peak value of the photoinduced birefringence appeared at about 0℃ C. The effect of temperature on the photoinduced birefringence is discussed using the competition mechanism between the photoinduced reorientation and the thermal random motion.     

4,4′ -二偶氮苯重氮氨基偶氮苯与Ag(Ⅰ)的显色反应及其应用

本文报道了4,4′ -二偶氮苯重氮氨基偶氮苯在Triton X-100存在下与Ag(Ⅰ)的显色反应.在pH10.0的硼砂-氢氧化钠缓冲溶液中,试剂与Ag(Ⅰ)形成1∶1的红色配合物,其最大吸收波长为540nm,表观摩尔吸光系数为7.55×104L*mol-1*cm-1,Ag(Ⅰ)的浓度在0-0.28mg/L范围内符合比耳定律.应用于显影废液和钮扣电池液中Ag的测定,结果令人满意.     

由苯经水促高选择性阳极乙酰氧化法一步合成乙酸苯酯

采用恒电流方法,电解苯和乙酸一步合成乙酸苯酯,研究了水对反应效率的影响．和无水体系相比,加入水提高了反应的电流效率和乙酸苯酯的选择性．在优化得到的最佳反应条件下,反应的电流效率和产物的选择性分别可达4.8%和96%．乙酸苯酯的浓度随着时间的延长呈线性增加的趋势,反应12 h后乙酸苯酯的浓度达1.07 g/L,选择性保持在95%以上．反应机理的研究表明,该反应可能涉及吸附活化苯的机理,主要副反应是Kolbe反应．水的加入促进了苯在铂片电极表面的吸附,从而提高了反应的效率和乙酸苯酯的选择性.     

同步扫描－固体基质室温磷光法同时测定痕量对位三联苯和间位三联苯的研究

本文提出了一种新的测定间三联苯和对三联苯的同步扫描－ＳＳ－ＲＴＰ法。固体基质选用慢速定量滤纸，重原子盐为Ｔｌ２ＳＯ４。以激发单色器和发射单色器的波长差△λ＝１８０ｎｍ进行同步扫描，其同步特征峰间三联苯为４５０ｎｍ，对三联苯为４９０ｎｍ（均指发射波长）。间三联苯可直接由该特征峰的高度进行定量测定。对三联苯在４９０ｎｍ处的特征峰略受间三联苯同步拖尾的影响，其峰值信号需加校正。间三联苯和对三联苯的线性范围分别为０．４６～９２ｎｇ／斑点和０．４６～４６ｎｇ／斑点     

激发态卟啉衍生物研究(Ⅶ)——取代基对卟啉—硝基苯化合物发光特性的影响

本文报导共价链相连的X-P-Y“三合板”型化合物在二甲基甲酰胺(DMF)和苯溶液中的发光特性.结果发现:引入取代基X=Cl—,CH3O—和Y=苯、硝基苯对中心卟啉的吸收和荧光光谱均无明显影响,仅其峰值频率将因溶剂不同而有所偏移.此外,由Cl—取代的卟啉—苯的荧光强度总比CH3O—取代时高;若将Y取代基由苯改换为硝基苯时,将使CH3O—P—Y化合物的荧光增强,但在Cl—P—Y化合物中则出现相反的趋势.不论在何种化合物中,在Y取代基中的苯环上引入NO2—基后,均可使其消光系数减小,而且当硝基在邻位取代时,这一效应更为显著.所有这些变化规律均不因溶剂不同而异.如果我们认为X—P—Y化合物的发光强度变化和其中心的卟啉大环上的π电子云密度偏移有规律性的关联,那么上述的一些取代基效应是可以理解的.进而,我们认为:本文所报导的事实将有助于充实巧妙设计高效利用太阳能的分子体系的科学依据.     

Photo-electrochemical properties of multi-layered thin films composed of chalcogenide and superionic conductor glasses

Multi-layered thin films, which consisted of metallic silver, GeSe₃ glass, and silver oxyhalide superionic conductor glass were prepared. Photo- and electrochemical reaction of metallic silver with the chalcogenide glass layer was studied by optical absorbance and cyclic-voltammetry. Photo-doping of silver through the superionic glass layer was observed using evaporated AgI---Ag₂MoO₄ film and it was partly undoped by electrochemical treatment. However, no photo-doping was observed for the cell consisting of a AgI---AgPO₃ dip-coated layer. The doped silver was dissolved into the GeSe₃ layer during the photo-doping process. However, it formed another intermediate compound layer (probably silver selenide) during the electrodoping process.     

质子酸功能化离子液体中银纳米颗粒的制备及其光学性能研究

以质子酸功能化离子液体1-丁基-3-甲基咪唑磷酸二氢盐([Bmim]H₂PO₄)为反应介质和表面活性剂,采用简单的化学还原法制备了具有形状各向异性的块状银纳米颗粒。通过X射线衍射(XRD)、扫描电镜(SEM)、紫外-可见(UV-Vis)吸收光谱等一系列手段对其结构、形貌及光吸收特性进行了表征。结果表明,所制备的银纳米块具有立方结构,其平均横向尺寸约为30 nm,在硅片上自组装形成密堆积结构的多层膜。以1,2-二(4-吡啶基)乙烯(BPE)作为探针分子,研究所制备银纳米颗粒的表面增强拉曼散射(SERS)活性。结果表明所制的银纳米颗粒是较好的SERS基底,具有良好的增强效果,痕检能力及稳定性。对BPE分子的最低检测浓度可低至10-9mol·L-1,而且保存了90天后,其检测灵敏度没有显著的降低。     

SERS characterization of metallic silver nanoparticle self‐assembly within thin films

Clusters of silver nanoparticles are generated by the thermally initiated reduction of silver carboxylates (long‐chain fatty acids) in the thin polymer films. The size, shape, and aggregation of these nanoparticles are affected by the reduction reaction in the presence of capping agents. In order to understand the mechanism(s) controlling the silver structure formation, it is essential to understand the surface coordination chemistry occurring during this process. We now report the first application of surface‐enhanced Raman spectroscopy (SERS) to directly characterize adsorbates on the surfaces of silver nanoparticles within a thin film imaging construction containing multiple components. In addition, SERS investigation of model silver substrates was used to confirm the identify of specific adsorbates of silver complexes. This is a powerful tool for revealing the chemistry involved with the control of silver nanoparticle aggregation during thermally induced metallic silver formation within thin films. Both the catechol‐reducing agent and the phthalazinone (PAZ) particle aggregation agent are observed on the metallic silver surface at the initial particle formation and during its crystal growth. However, careful attention to excitation wavelength is required in order to observe all the surface species. PAZ appears to be more effective at stabilizing individual silver particles than other aggregation agents investigated. An understanding of the roles of the aggregation/reducing agents in the growth and aggregation of silver nanoparticles is important for preparing different types of silver particles for specific applications including silver‐based thermal imaging systems. Copyright © 2008 John Wiley & Sons, Ltd.     

Formation of silver colloids in silver ion-exchanged soda-lime glasses during annealing

The structural and compositional changes of the soda-lime glasses during the formation of the silver colloids were analyzed by the X-ray Photoelectron Spectroscopy (XPS) in order to examine the silver colloid formation mechanism. The in situ behavior of silver and SiO₂ networks on the surfaces of silver ion-exchanged soda-lime glasses during heating and cooling processes in ultra-high vaccum was monitored. The results showed that silver diffuses toward the surface, precipitates, and crystallizes during heating and the total silver surface concentration is slowly increased during cooling. The concentration changes of oxidized and neutral Ag, a new non-bridging oxygen species (NBO^*), and a new silicon species (Si[a]) were applied to deduce a disappropriation reaction mechanism of Ag⁺ on the surface during annealing. The SiO₂ network is modified at temperatures below 350°C to accommodate more silver on the surface and to balance the extra charge carried by the Ag⁺. That the SiO₂ network polymerizes during annealing was deduced from the results of the higher binding energies of Si2p and O1s after annealing. This observation suggests that the reduction of the Gibbs free energies and the relaxation of tensile stress result in the formation of the silver colloids under thermal annealing.     

A simple method for the preparation of ultrahigh sensitivity surface enhanced Raman scattering (SERS) active substrate

By immersing mica modified with cetyltrimethylammonium bromide (CTAB) into the silver colloid, a high efficient surface enhanced Raman scattering (SERS) active substrate was formed within 2 h at room temperature. The limit of detection of the substrate for Rhodamine 6G is up to 1×10⁻¹⁴ M. Changing the concentration of silver colloid and the treating time, various silver aggregates such as nanocrystals, clusters and films were found, and the SERS spectra of these aggregates were also obtained. The results of SERS revealed that CTAB could accelerate aggregation of the silver colloid and cause great Raman enhancement. Bilayer of CTAB is very important for aggregation of silver colloid and the aggregation extent is the main factor for the enormous enhancement on this substrate.     

Surface Enhanced Raman Scattering on Self-assembled Nano Silver Film Prepared by Electrolysis Method

用一种廉价的电解方法制备了纳米银膜,并详细研究了在这种银膜上的表面增强拉曼散射效果．结晶紫为本实验的检测性分子．通过实验发现,这种银膜用便携式拉曼光谱仪测试并计算出的表面增强拉曼散射的增强因子为603,并对结晶紫的最小检出限为0.1 nmol/L     

A promising approach to conductive patterns with high efficiency for flexible electronics

A promising approach for conductive patterns with high efficiency for flexible electronics was developed by direct-writing, silver(I) solution (silver nitrate, acetate silver, etc.) with no solid particles as a conductive ink, conductive pen as a writing implement, and polyimide (PI) film as a substrate. The physical properties of the conductive ink were investigated by a dynamic contact angle system, ubbelohde viscometer and surface tension instrument. Conductive properties of silver ink film were investigated by 4-point probe, scanning electron microscope (SEM) and surface profilometer. It is demonstrated how the design of solvent composition in conductive ink affects surface morphology, and conductivity of silver ink films. It can be obtained that conductive patterns drawn on PI substrate not only have good mechanical/electrical fatigue properties, but also have low resistivity. Especially, when the sintering condition is 200 °C for 60 min, the resistivity can be down to 6.6 μΩ cm, 4.25 times the silver bulk resistivity.     

Sensitive surface-enhanced Raman scattering substrates based on anti-pyramidal gold architectures decorated with silver nanoparticles

Abstract

A micro-structured gold surface, consisting of a periodic square–based anti–pyramidal array (Klarite) with a smooth boundary surface on which silver nanoparticles (diameter: 60?nm) were deposited, produced an active surface enhanced Raman scattering substrate. With p-aminothiophenol as a probe molecule, the Raman activity of the micro–structured surface was compared before and after deposition of the silver nanoparticles. Experimental results show that the Raman spectra on the silver/p-aminothiophenol/Klarite structure is stronger than that on the silver/p-aminothiophenol/gold film and the Raman spectra on the silver/p-aminothiophenol/gold film is stronger than that on silver/p-aminothiophenol, p-aminothiophenol/Klarite structure, p-aminothiophenol/gold film, which is confirmed by numerical simulations. A similar result is obtained with crystal violet as test molecule.     

Importance of poly(ethylene glycol) conformation for the synthesis of silver nanoparticles in aqueous solution

Silver nanoparticles (NPs) were prepared using silver nitrate (AgNO₃) as a precursor in an aqueous solution of poly(ethylene glycol) (PEG), which acted as both a reducing and stabilizing agent. The UV/Vis spectra showed that PEG 100 (100 kg/mol) has a remarkable capability to produce silver NPs at 80 °C, but the production of silver NPs by both PEG 2 (2 kg/mol) and PEG 35 (35 kg/mol) was negligible. This difference was explained by the conformation of PEG in the reaction solution: the entangled conformation for PEG 100 and the single-coiled conformation for PEG 2 and PEG 35, which were confirmed by pulse-field-gradient ¹H NMR and viscosity measurements. In an aqueous solution, the entangled conformation of PEG 100 facilitated the reduction reaction by caging silver ions and effectively prevented the agglomeration of formed NPs. The reaction in an aqueous PEG 100 solution was observed to be stable under the conditions of a prolonged reaction time or an increased temperature, while no reduction reaction occurred in the PEG 2 solution. The synthesis of silver NPs by PEG 100 was well controlled to produce fine silver NPs with 3.68 ± 1.03 nm in diameter, the size of which remained relatively constant throughout the reaction.     

Polymer-Nanoparticle Composites Composed of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Coated Silver Nanoparticles

The effects of addition of synthesized organic-suspension silver nanoparticles on the crystallization and thermal stability of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were studied by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD), UV-Vis absorption spectroscopy, polarized optical microscopy (POM), and thermal gravimetric analysis (TGA). The TEM images showed the average primary size of the as-synthesized silver nanoparticles, coated with a monolayer of the surfactants consisting of oleic acid and an alkylamine, was about 5 nm with narrow distribution, and that they were uniformly dispersed in n-heptane. PHBV/silver nanocomposites were prepared by melt mixing in an internal mixer and then injection molded into rectangle-shaped specimens by a labscale injection molding device. The coated silver nanoparticles showed a homogenuous dispersion in the PHBV matrix when the content of coated silver nanoparticles was about 1%. Both the DSC and POM data showed the efficient heterogeneous nucleation by the coated silver nanoparticles for facilitating PHBV crystallization. The thermal stability of the PHBV/silver nanocomposites improved with the increase in the content of the coated silver nanoparticles.