共查询到20条相似文献,搜索用时 86 毫秒
1.
本文通过研究在不同溶剂中蒈烯对9,10-二腈基蒽(DCA)荧光猝灭的光物理特性及溶剂极性对猝灭速度的影响,温度效应的测定及其在乙腈中双分子猝灭速率常数kq值与计算所得自由能的变化(△G)之间的关系符合 RehmWeller关系,证明了菇烯对DCA荧光的猝灭是一个电子转移的动态猝灭过程。 相似文献
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研究了苊酮(ANO)对9,10-二氰蒽(DCA)的荧光猝灭与激基络合物形成的动力学与机理,基于瞬态荧光双指数衰减,测定了激基络合物的光化学动力学和有关速度常数,论证荧光猝灭作用主要由ANO/DCA激基络合物的生成以及快速正向电子转移所致。 相似文献
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本工作对硝酮化合物猝灭9-氰蒽荧光的机制进行了研究,发现不同的9-氰蒽/硝酮体系可能经历包括电子转移、能量转移及竞争吸收等不同的猝灭过程。其中α,N-二苯基硝酮对荧光猝灭遵循电子转移机制,分别形成猝灭剂和敏化剂的离子自由基,但硝酮正离子自由基不能导致环化反应发生,结果还表明:硝酮化合物的四π电子1,3偶极结构在猝灭过程中起主要作用,因此当光环化反应破环1,3偶极结构生成氧氮丙啶时,即失去其原有的猝灭能力,导致已被猝灭的荧光重新回复。 相似文献
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二溴苯基荧光酮荧光猝灭法测定铟 总被引:2,自引:0,他引:2
1引言自1978年合成了4,5-二溴苯基荧光酮(简称DBPF)以来,DBPF作为一种高灵敏显色剂得到了广泛的应用。该试剂在胶束增溶光度分析中灵敏度非常高,广泛用于光度法测定金属离子。但利用DBPF作为荧光剂测定痕量In(Ⅲ)的方法尚未见报道。本文研究了在表面活性剂CTMAB存在下·In(Ⅲ)与DBPF的荧光猝灭体系,在pH4.0的HCl/NaAc介质中,以400nm为激发波长,体系在535nm处荧光强度达到最大,痕量钢的加入对该体系荧光有很强的猝灭作用。在0~160μgIn(Ⅲ)/L范围内呈线性… 相似文献
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荧光猝灭法测定壳聚糖含量 总被引:2,自引:0,他引:2
在pH 6.3的NaH2PO4-Na2HPO4缓冲溶液中,壳聚糖对荧光素的荧光强度具有明显的猝灭作用,且在一定浓度范围内,其猝灭程度与加入的壳聚糖浓度成线性关系,据此建立了一种新的测定壳聚糖含量的荧光猝灭分光光度法。该方法的回归方程为ΔF=64.02+42.28ρ(mg/L),R2=0.9942,线性范围为0.50~10.0 mg/L,检出限为0.27 mg/L。样品测定的RSD为4.5%(n=6),平均回收率为99.3%。采用该方法可测定复杂样品中的壳聚糖含量。 相似文献
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Ashok H. Sidarai Vani R. Desai Shirajahammad M. Hunagund Mahantesha Basanagouda Jagadish S. Kadadevarmath 《Journal of solution chemistry》2017,46(6):1328-1336
The steady-state fluorescence quenching of novel coumarin derivatives; 4-(2, 6-dibromo-4-methyl-phenoxymethyl)-benzo[h]chromen-2-one [DMB] and 6-methoxy-4-p-tolyoxymethyl-chromen-2-one [TMC] has been studied in toluene, benzene, dioxane, acetonitrile and tetrahydrofuran [THF] using aniline as a quencher at room temperature with a view to understanding the role of diffusion in the quenching mechanism. The probability of quenching per encounter (p) is calculated in all the solvents. Further, an activation energy for quenching (E a) was estimated using the values of p and the literature values of activation energy for diffusion (E d). The magnitudes of these parameters indicate that the fluorescence quenching of these molecules by aniline is not solely due to the material diffusion but there is also a contribution of an activation energy. 相似文献
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《Analytical letters》2012,45(7):379-385
Abstract A fluorescence quenching method for the determination of fluoride ion over the concentration range from 10?9 to 10?6M is presented. The fluoride ion is added to the fluorescent chelate of aluminum(III) and PAN [1- (2-pyridylazo)-2-naphthol]: the fluoride preferentially complexes the aluminum (III), displacing nonfluorescent PAN. Of the anions tested as possible interferences at equimolar levels, phosphate interferred seriously and iodide interferred somewhat. 相似文献
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氨基酸残基对探针分子的荧光猝灭行为可以为生物大分子的结构及构象动力学研究提供重要的信息.本文运用飞秒瞬态吸收光谱和时间相关单光子计数实验系统研究了在水(H2O)和氘代水(D2O)溶液中乙酰基取代酪氨酸(AcTyr)对Eosin Y的超快荧光猝灭动力学过程.发现导致AcTyr对Eosin Y荧光猝灭的主要原因是由于它们之间形成了短寿命的基态复合物.我们还发现Eosin Y与AcTyr形成的基态复合物的激发态寿命具有明显的动力学同位素效应,表明AcTyr对Eosin Y的荧光猝灭是通过质子耦合电子转移过程发生的. 相似文献
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建立了通过磷酰化氨基酸水解产生无机磷酸盐猝灭铽离子-钛铁试剂络合物(Tb3 -TR)荧光探针的间接荧光法测定三种磷酰化氨基酸。在最佳实验条件下,方法测定磷酰化丝氨酸(P-Ser)、磷酰化苏氨酸(P-Thr)和磷酰化酪氨酸(P-Tyr)的线性范围分别为5.0×10-8~5.0×10-7mol/L、5.0×10-8~6.0×10-7mol/L、5.0×10-8~6.0×10-7mol/L;检出限分别为2.06×10-8mol/L、1.13×10-8mol/L和1.74×10-9mol/L。该方法最后用于卵黄高磷蛋白中含磷量的测定,取得定量结果。 相似文献
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Ignacy Gryczynski Zygmunt Gryczynski Joseph R. Lakowicz 《Photochemistry and photobiology》1998,67(6):641-646
We demonstrated that fluorescence anisotropy can be effectively decreased or increased in the presence of light quenching, depending on relative polarizations of excitation and quenching pulses. For parallel light quenching, anisotropy decreases to 0.103 and z-axis symmetry is preserved. In the presence of perpendicular light quenching, the steady-state anisotropy of a pyridine-2-glycerol solution increases from 0.368 for an unquenched sample to 0.484 for a quenched one. We show that the angular distribution of transition moments loses z-axis symmetry in the presence of perpendicular light quenching. In these cases we used more general definitions of anisotropy. Induced by light quenching, anisotropy can be applied in both steady-state and time-resolved measurements. In particular, the systems with low or no anisotropy can be investigated with the proposed technique. 相似文献
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Abstract— The combination of steady-state and time-resolved quenching experiments was employed to study the aggregation behavior of sodium cholate at concentrations below 50 mAf. Naphthalene, anthracene and pyrene were used as fluorescent probe molecules, and protection by the aggregates from aqueous quenchers, as well as the onset of aggregation at low sodium cholate concentrations, was dependent on the shape of the probes. Protection from aqueous quenchers was inferred by comparing the efficiency for dynamic quenching in the absence and presence of sodium cholate and was best for naphthalene followed by pyrene and anthracene. Static quenching was observed, suggesting that probe molecules are located in an aggregate environment that also contains iodide. The incorporation of pyrene at low sodium cholate concentrations, as well as the small degree of static quenching observed, suggest that the shape complementarity, i.e. hydrophobic surface and packing, between pyrene and sodium cholate is optimum for aggregate formation. 相似文献
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The fluorometric determination of periodate with tetraiodofluorescein has been developed. Under the optimum conditions responses
were linear between 4.0×10−7 ∼ 1.0 × 10−5 mol/L of periodate. The detection limit was 1.0 × 10−7 mol/L corresponding to a signal to noise ratio of 2. The proposed method was applied to the determination of periodate in
artificial fresh water and kelp sample with good results.
Received March 20, 2001 Revision December 19, 2001 相似文献
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We developed a new method to measure the average aggregation number of large rod-like micelles using static fluorescence self-quenching of a solubilized fluorophore. The method is based on the increase of self-quenching of micelle-solubilized pyrene through excimer formation. We consider the effect of random distribution of pyrene in micelles and the micellar size distribution. The measured average aggregation <n> M is based on a new M-weighted raging similar to our exponential-weighted averaging in the transient decay method. We apply this method to study the effect of a large concentration of salt on the average aggregation behavior of sodium dodecyl sulfate (SDS) and cetyle tetraammonium bromide (CTAB). The sizes increase with increasing ionic concentrations. For SDS, we used the thermodynamic model developed by Missel et al. to calculate < n > M which we compare with experimental results. 相似文献
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Mohammad-Reza Rashidi Moharam Dehghany Golamreza Dehghan Abolghasem Jouyban Akram Faridi 《Applied biochemistry and biotechnology》2013,169(3):901-910
In this study, the catalytic activity of aldehyde oxidase was investigated in various water-miscible organic solvents for the first time. The enzyme was partially purified from rabbit liver, and its activity was determined in the absence/presence of nine hydro-organic mixtures. The effects of pH and temperature on the enzyme activity were also investigated. The activity was reduced in the presence of all nine organic solvents. However, in some cases, the residual activity remained almost unchanged throughout the incubation of enzyme at 35 °C for 24 h. Considering potential advantages of doing reactions in the presence of organic solvents, these results could be of value. The enzyme showed different behavior in the reaction solutions making it difficult to formulate results in a single comprehensive model. The results indicated that binding and cleavage of the substrate are influenced in the presence of organic solvents. 相似文献
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动力学荧光猝灭法测定痕量铜 总被引:7,自引:0,他引:7
研究了在稀盐酸介质中,铜(Ⅱ)催化过硫酸钾氧化磺化钾,生成的I^-3与罗丹明6G生成缔合物而使罗丹明,6G荧光猝灭,建立了催化荧光法测定痕量铜的方法,线性范围为4-54检出限为1.6μg/L。 相似文献