Triplet states of humic acids studied by laser flash photolysis using different excitation wavelengths

The spectra and kinetics of short-lived intermediates formed from aqueous (0.1 N NaOH) solutions of the natural mixture of humic and fulvic acids (HFA) were studied by laser flash photolysis using excitation wavelengths of 337, 390, 470, and 520 nm. Laser photolysis of HFA with light of 520 and 470 nm results in the formation of triplet excited states (T_HFA) characterized by the broad absorption spectrum with a maximum near 630 nm and lifetimes of 0.15 ms in deoxygenated solutions. The formation of two types of T_HFA with lifetimes of 0.1 and 2 ms and absorption spectra with maxima at 570 nm is observed under photolysis with light of 337 and 390 nm. The estimation of quantum yields of T_HFA gives 1 and 0.3% under photolysis with excitation wavelengths of 337 and 520 nm, respectively. The rate constants of T_HFA quenching by molecular oxygen are equal to (7—8)·10⁸ L mol^–1 s^–1.     

基于荧光熄灭的二氧化硫选择性光化学敏感膜的研究

本文基于二氧硫对固定于增塑的聚氯乙烯膜上的芳香稠环化合物蒽的荧光熄灭，研制了二氧化硫选择性光化学敏感膜，经过组成优化 的敏感膜测定二氧化硫的浓度范围为6．59×10^-3-5.23×10^-1mol/L，校正曲线与理论推导的模拟曲线相吻合，且荧光信号具有较高的重现性，信号响应时间为5－30s.     

Effect of the coordination sphere of d<Superscript>0</Superscript> metallocene on triplet-triplet energy transfer

The triplet nature of rare long-lived states of d⁰ metallocenes formed upon ligand-to-metal energy transfer was confirmed by studies of triplet-triplet charge transfer in biscyclopentadienyl complexes Cp₂MCl₂ (M = Zr (1), Hf (2)). The interaction between precatalysts and substrates of catalytic polymerization systems, viz., complexes 1 and 2 and unsaturated hydrocarbons (alkenes and dienes), was studied in the region of concentrations close to catalytic values. For organometallic π-complexes, it has been shown for the first time that, in the case of the unsaturated hydrocarbons, the efficiency of energy transfer obeys the Perrin equation. The process occurs at distances R ₀ close to the diameter of the interacting molecules and is well described by the exchange-resonant mechanism of interaction. In the case of the cyclopentadiene-Cp₂MCl₂ (M = Zr, Hf) systems, R ₀ = 14.6 Å. A linear relationship between the critical radius of the quenching sphere R ₀ and the number of carbon atoms in a linear α-olefin has been revealed for the first time and evidences the formation of a π-complex between the precatalyst and substrate molecules. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 35–39, January, 2007.     

部分水解聚丙烯酰胺在多孔介质中的静态吸附研究——水解度对吸附量的影响

部分水解聚丙烯酰胺在多孔介质中的静态吸附研究———水解度对吸附量的影响杨继萍李惠生黄鹏程（北京理工大学化工与材料学院北京１０００８１）（北京航空航天大学材料科学与工程系北京１０００８３）关键词部分水解聚丙烯酰胺，水解度，多孔介质，静态吸附聚合物作为...     

Effects of diclofenac on EPC liposome membrane properties

In this work the interaction of a non-steroidal anti-inflammatory drug (NSAID), diclofenac, with egg yolk phosphatidylcoline (EPC) liposomes, used as cell-membrane models, was quantified by determination of the partition coefficient. The liposome/aqueous phase partition coefficient was determined by derivative spectrophotometry, fluorescence quenching, and measurement of zeta-potential. Theoretical models based on simple partition of the diclofenac between two different media, were used to fit the experimental data, enabling the determination of K_p. The three techniques used yielded similar results. The effects of the interaction on the membranes characteristics were further evaluated, either by studying membrane potential changes or by effects on membrane fluidity. The liposome membrane potential and the size and size-homogeneity of liposomes were measured by light scattering. The effects of diclofenac on the internal viscosity or fluidity of the membrane were determined by use of spectroscopic probes—a series of n-(9-anthroyloxy) fatty acids in which the carboxyl terminal group is located at the interfacial region of the membrane and the fluorescent anthracene group is attached at different positions along the fatty acid chain. The location of the diclofenac on the membrane was also evaluated, by fluorescence quenching using the same series of fluorescent probes. Because the fluorescent anthracene group is attached at different positions along the fatty acid chain, it is possible to label at a graded series of depths in the bilayer. The interactions between the drug and the probe are a means of predicting the location of the drug on the membrane.     

电极材料对NPB/Alq3有机电致发光器件性能的影响

采用不同材料作为有机电致发光器件(OELDs)的电极, 制备了基本结构为[阳极/NPB(40 nm)]/Alq3(50 nm)/阴极]的异质结双层器件, 并通过改变OELDs器件的阴极或阳极来研究电极材料对器件光电性能的影响. 研究结果表明, 各器件电流-电压(I-V)关系的基本特征与陷阱电荷限制电流(TCLC)机制的拟合情况相符. 由于有机材料本身能级的无序性以及载流子迁移率对温度和电场的依赖性, 不同电极的载流子注入能力与其功函数并无直接关系. 双层器件中由于空穴传输层的引入, 使得载流子复合区域位于有机层异质结界面处, 降低了金属阴极对激子的猝灭作用, 从而大大提高了器件性能. 此外, 金属电极OLEDs器件结构具有的微腔效应会导致发射光谱的位移和谱峰宽度变窄, 这表明通过对金属电极的表面改性和优化可使器件性能超过常规结构的器件.     

二溴羟基苯基荧光酮—乳化剂OP荧光熄灭法测定微量铬（Ⅵ）

本文基于Ｃｒ（Ⅵ）－二溴羟基苯基荧光酮（ＤＢＨ－ＰＦ）－ＯＰ体系的荧光熄灭效应，提出一种测定痕量铬（Ⅵ）的新荧光方法。在ｐＨ２．４－４．１的ＨＣｌ－ＮａＡｃ缓冲介质和ＯＰ存在下，Ｃｒ（Ⅵ）与ＤＢＨ－ＰＦ形成１：２的橙红色络合物，络合物的最大激发发工和发射波长分别是３６５ｍｍ和５２８ｎｍ。铬（Ⅵ）量在０．０５－１．５μｇ／２５ｍｌ范围内与△Ｆ呈线性关系，检测限是２．０ｎｇ／ｍｌ。方法用于电镀废液，废     

相反转技术制备环氧树脂水基体系——相反转过程的流变行为研究

对高乳化剂浓度下的相反转发展过程的流变行为进行了应力扫描、动态频率扫描实验表征．结果表明，乳化剂浓度较高时，体系发生完全相反转；体系在相反转点前为Ｗ／Ｏ结构，其粘度几乎不随剪切应力的改变而改变，表现为牛顿流体行为；体系在相反转点后为Ｏ／Ｗ结构，具有很高的粘弹性，并且在较高剪切应力下表现为典型的假塑性．这是由于高分子水基微粒间通过其表面覆盖的表面活性剂与水形成氢键而产生了一种静态结构，此结构在较高剪切应力作用下破坏而导致假塑性．     

BaLaB_9O_（16）中Ce~（3＋）敏化Dy~（3＋）发光的机理

在紫外光激发下，研究了ＢａＬａＢ９Ｏ（１６）中Ｄｙ（３＋）、Ｃｅ（３＋）的发光光谱、激发光谱、发光强度及荧光寿命随着组成变化的规律性．结果表明：Ｄｅ（３＋）对Ｄｙ（３＋）的发光有相当强的敏化作用，Ｃｅ（３＋）→Ｄｙ（３＋）的能量传递效率可高达９３％，能量传递的机理为电偶极－偶极相互作用的共振传递．根据３４９ｎｍ激发下Ｄｙ（３＋）发光强度与浓度的关系，证明了Ｄｙ（３＋）发光的自身浓度猝灭机理也为电偶极－偶极相互作用．     

Determination of trace silver by solid substrate room temperature phosphorescence quenching method based on lead carboxymethyl cellulose particles (Pb(CMC)2) containing luminescent salicyl fluorenes molecules

Luminescent particles of lead carboxymethyl cellulose (Pb(CMC)2) containing salicyl fluorones (THBF), Pb(CMC)2-THBF were synthesized by the sol-gel method, using sodium carboxymethyl cellulose (NaCMC) as precursor and Pb2+ as precipitant. Pb(CMC)2-THBF can emit the intense and stable solid substrate room temperature phosphorescence (SS-RTP) on filter paper. And EDTA can chelate Pb2+ in Pb(CMC)2-THBF, causing it to decompose into aqueous soluble components PbY2-, CMC- and THBF, which can react with Ag+ to form Ag(CMC)2-THBF, causing the decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace silver by SS-RTP quenching method was established. The linear range of this method is 8.0-40.0 fg spot(-1) (20.0-100.0 pg ml(-1)), with a detection limit (LD) of 2.2 fg spot(-1) (corresponding to a concentration range of 5.5 x 10(-13) g ml(-1)), and the regression equation of working curve is DeltaI(p) = 12.56 + 0.5527C(Ag+) (fg spot(-1), 0.4 microl spot(-1)), n = 8, r = 0.9992. This method has been applied to the determination of trace silver in human hair and tea sample with satisfactory results. The mechanism of SS-RTP emission is also discussed.