Silver nanoparticles dispersed within amphiphilic star-block copolymers as templates for plasmon band materials

Formation of silver nanoparticles has been developed based on a template technique. Amphiphilic star-block copolymers employed as single molecule template, utilizing the coordination of Ag⁺ ions with carboxyl groups in the core of the star-block copolymer. Silver nanoparticles have been prepared by the addition of chemical reductant, e.g., NaBH₄. The solution of the resultant nanosphere composites showed yellow due to the surface plasmon resonance. These composites were soluble in organic solvents, because hydrophobic corona of the star-block copolymer protected the fabricated silver nanoparticles from aggregation.     

Determination of heavy metal concentration in feed and permeate streams of polymer enhanced ultrafiltration process

Polymer enhanced ultrafiltration (PEUF) is a newly developed method for the removal of heavy metals from aqueous solutions. This method was applied for the removal of mercury and cadmium with the presence of polyethyleneimine (PEI) as a water soluble polymer. After ultrafiltration experiments for metal–polymer mixtures, two separate streams, namely, retentate and permeate, former of which contains mainly metal–polymer complex and free polymer molecules while latter of which mainly contains free metal ions, were obtained. At the end of PEUF experiments, performance of operation was determined by concentration analyses which was achieved by atomic absorption spectroscopy (AAS) applied in a different way for permeate and retentate streams considering the effect of presence of polymer. For mercury analysis, cold vapor AAS was applied. It was observed that the presence of PEI did not affect the atomic absorption signal when 10% HCl was added to the sample solutions. For calcium and cadmium, flame AAS was used. It was observed that change in PEI concentration results in change in measured concentration of calcium and cadmium. Therefore, two new approaches were developed for accurate measurement of concentrations of calcium and cadmium. It was also observed that presence of other metals did not affect the accuracy of the measurement of a particular metal in the concentration range studied.     

硅灰石矿物发光原料中Fe2+的去除与CaSiO3∶Eu3+的光谱特性

提出了用草酸．邻菲哕啉去除硅灰石中Fe^2 的方法，研究了浸取剂的浓度、浸取时间和温度等条件对Fe^2 的去除率的影响，在最佳的浸取条件下，Fe^2 的去除率达到98．35％。在去除猝灭剂后的硅灰石矿物中，掺加适量的稀土激活剂Eu^3 ，通过高温固相法制成荧光发光材料，发光强度明显提高，接近于化学试剂合成的发光材料。     

A Novel Proton Sensor with Luminescence and Color Signaling Based on Platinum(II) Terpyridyl Acetylide Complex

Molecular switches that are controllable, reversible and readable at molecular level are an essential compo-nent of molecular electronics1 and chemical sensors.2-6 Of particular interest are the molecules which show dramatic and reversible changes in color and/or lumi-nescence in visible spectral region upon exposure to specific substrates. A number of chromophore- spacer-receptor systems that can selectively recognize specific guest molecules at their receptor site and pro-duce measurable col…     

Temperature-sensitive luminescence of tris (β-diketone) europium chelates for monitoring high-speed cationic photopolymerizations

The temperature-dependent luminescence of tris (β-diketone) chelates of europium was used for in situ temperature measurements during cationic photopolymerizations of vinyl ethers. These molecular-level luminescent probes provided a real-time, noninvasive method for monitoring temperature during these high-speed polymerizations. Two specific probes, tris (benzoyl-1, 1, 1-trifluoroacetone) europium and tris (1,1,1,5,5,5,-hexafluoroacetylacetone) europium, met several stringent spectral and performance requirements for application in our system. The luminescence from these probes exhibits a reproducible temperature dependence over a wide temperature range and is not sensitive to changes in viscosity. In situ temperature profiles obtained using this novel technique verified the importance of thermal effects during these highly exothermic photopolymerizations. These studies have demonstrated the utility of the tris(β-diketone) europium chelates for characterizing the temperature during high-speed photopolymerizations that cannot be monitored using conventional techniques. © 1995 John Wiley & Sons, Inc.     

Sm~(3 )在硼酸盐玻璃中的发光及Bi~(3 )对Sm~(3 )的敏化作用

早在六十年代,人们为了寻找较好的激光玻璃,曾对Sm~(3 )离子掺杂的玻璃中的光谱进行过研究。为了探寻新型的激光,发光玻璃,又进一步研究了Sm~(3 )在玻璃中的发光和敏化。我们以寻找一种高亮度,低成本的发光玻璃为目的,研究了基质玻璃组成,敏化离子及其浓度对Sm~(3 )发光性质的影响。 选择B_2O_3-BaO-M_mO_n(M_mO_n=Li_2O,Na_2O,K_2O,MgO,CaO,SrO)玻璃体系,所用原料的纯度皆为分析纯以上,用陶瓷坩埚在1250℃掺杂氧化钐(纯度均大于99％),玻璃的荧光谱和激发光谱,用MPF-4型荧光分光光度计测定。     

Adsorption of -histidine on copper surface as evidenced by surface-enhanced Raman scattering spectroscopy

The adsorption of -histidine on a copper electrode from H₂O- and D₂O-based solutions is studied by means of surface-enhanced Raman scattering (SERS) spectroscopy. Different adsorption states of histidine are observed depending upon pH, potential, and the presence of the SO²⁻₄ and Cl⁻ ions. In acidic solutions of pH 1.2 the imidazole ring of the adsorbed histidine remains protonated and is not involved in the chemical coordination with the surface. The SO²⁻₄ and Cl⁻ ions compete with histidine for the adsorption sites. In solutions of pH 3.1 three different adsorption states of histidine are observed depending on the potential. Histidine adsorbs with the protonated imidazole ring oriented mainly perpendicularly to the surface at potentials more positive than −0.2 V. Transformation of that adsorption state occurs at more negative potentials. As this takes place, histidine adsorbs through the α-NH₂ group and the neutral imidazole ring. The Cl⁻ ions cause the protonation and detachment of the α-NH₂ group from the surface and the formation of the ion pair NH⁺₃ … Cl⁻ can be observed. In the neutral solution of pH 7.0 histidine adsorbs through the deprotonated nitrogen atom of the imidazole ring and the α-COO⁻ group at E ≥ −0.2 V. However, this adsorption state is transformed into the adsorption state in which the α-NH₂ group and/or neutral imidazole ring participate in the anchoring of histidine to the surface, once the potential becomes more negative. In alkaline solutions of pH 11.9 histidine is adsorbed on the copper surface through the neutral imidazole ring.     

Specific features of luminescence of Q-CdS colloids with different sizes

The specific features of luminescence of colloidal solutions of Q-CdS with particles of different size and the regularities of luminescence quenching by quenchers of various nature were studied. The luminescence spectra of Q-CdS consist of several bands, which are shifted to the long-ware region as the particle size increases. The dependence of the integral quantum yield of luminescence on the particle size has a sharp maximum at a particle diameter of ?23Å. A Stem—Volmer-type equation including the adsorption isotherm of the quencher molecules on the surface of the Q-CdS colloidal particles was used to describe the regularities of luminescence quenching of Q-CdS colloidal solutions. The CdS particle size was found to affect the efficiency of luminescence quenching. The regularities of luminescence quenching depend both on the rate constant of electron transfer to the quencher molecules and on the ability of the quencher molecules to be adsorbed on the surface of the CdS colloidal particle.     

金属离子对中位─四（4─N甲氧羰甲基吡啶）卟啉表面增强拉曼光谱的影响

研究了金属离子对吸附在银胶表面的中位－四（４－Ｎ甲氧羰甲基吡啶）卟啉表面增强拉曼光谱的影响。结果表明，中位－四（４－Ｎ甲氧羰甲基吡啶）卟啉可发生金属离子取代反应。金属离子嵌入卟啉大环，吸附在银胶表面的中位－四（４－Ｎ甲氧羰甲基吡啶）卟啉转变为金属配合物。给出了各种金属配合物主要拉曼峰的经验式归属。金属离子的半径，ｄ电子对卟啉环的排斥作用，金属卟啉骨架模式频率随孔穴大小，大环的平面性和π－π相互作用而相应变化的特性，都可用来解释不同金属离子配合物的结构灵敏特征峰为何存在着差异。     

固溶体结构对Ca_(2-x)Sr_xZn_4Ti_(15)O_(36)∶Pr~(3+)发光性质的影响

0引言在绿色和蓝色长余辉发光材料达到应用程度之后,耐候性红色长余辉发光材料成为人们研究的重点。Eu3 、Sm3 激活的硫氧化物[1￣3]、Eu2 铝锶复合硫氧化物[4]和Y2O3∶Eu3 [5]等耐热耐水性红色长余辉材料被相继发现。Pr3 离子掺杂的碱土金属钛酸盐(M TiO3∶Pr,M=M g,Ca,Sr,Ba)是一种新型的红色长余辉发光材料。这种发光材料在615nm附近有很好的单色性红光发射。碱土金属钛酸盐基质化学性能稳定,已开始应用于场发射显示器(FE D)[6,7]。碱土金属钛酸盐是A BO3型化合物,具有钙钛矿结构。B all[8]曾通过在CaTiO3中掺入不同量的Sr2 …