氧化石墨烯如何猝灭罗丹明6G的荧光

考察了水相溶液中氧化石墨烯对罗丹明6G的高效荧光猝灭．借助稳态及时间分辨荧光光谱测量,结合对该二元体系线性吸收谱变化的细致分析,澄清了相关荧光猝灭机理,即动态猝灭与静态猝灭的联合猝灭机制．提出在静态猝灭过程中罗丹明6G与氧化石墨烯所形成的可能的基态复合物,并进一步讨论了二者之间的光致电子转移过程．     

Fe~(3+)对石墨烯氧化物荧光淬灭机理的研究

采用改进的Humer法合成了石墨烯氧化物,利用搭建的时间分辨光谱探测系统详细探究了Fe~(3+)(浓度为0.5、1、2 mmol/L)对石墨烯氧化物荧光淬灭物理机制。稳态荧光发射光谱中,随着Fe~(3+)浓度的增加,石墨烯氧化物的荧光强度急剧减弱。时间分辨荧光光谱和飞秒瞬态吸收光谱研究证实,加入不同浓度Fe~(3+)的GO其动力学衰减曲线基本没有任何变化。结果表明,Fe~(3+)对石墨烯氧化物的荧光淬灭主要是静态的荧光淬灭过程。     

Spectroscopic and Laser Studies of Mixed Rhodamine 6G and 10-Phenyl-9-acetoxyanthracene Solutions

The spectroscopic and laser parameters of a mixed donor (10-phenyl-9-acetoxyanthracene derivations)-acceptor (rhodamine 6G) solutions have been determined. The studies performed show that rhodamine 6G is responsible for the lasting of the mixed solution. The 10-phenyl-9-acetoxyanthracene added to the R6G lasing solution decreases the spectral range of lasing and the gain value, G(), of the solution. These changes in the lasing parameters are caused by electron energy transfer processes of different types. The results of fluorescence studies of the mixed donor-acceptor solutions point out that the long-range dipole-dipole interaction mechanism of the static quenching accompanied by the formation of nonemitting complexes in the dye mixture is responsible for the noted lasing and fluorescence changes.     

十二烷基苯磺酸钠胶束中吖啶橙与罗丹明6G间的能量转移机理研究

以吖啶橙(AO)与罗丹明6G(R6G)为例讨论了胶束介质中碱性荧光染料间相互作用的机理.在十二烷基苯磺酸钠水溶液中,吖啶橙与罗丹明6G染料分子间相互作用发生有效能量转移.在不同温度下,通过对能量转移体系研究,初步证明吖啶橙与罗丹明6G间发生能量转移引起吖啶橙的荧光猝灭为静态猝灭过程.通过热力学参数的计算,得出能量转移体系的结合力主要为静电引力.同时也对转移体系的能量转移效率,结合位点数和结合距离进行了计算.     

Fluorescence resonance energy transfer between acridine orange and rhodamine 6G and analytical application in micelles of dodecyl benzene sodium sulfonate

A new method for the determination of erythromycin by energy transfer fluorescence quenching of acridine orange (AO)—rhodamine 6G (R6G) in micelles solution studied and established. It was found that the effective energy transfer could occur between AO and R6G in the dodecyl benzene sodium sulfonate at and Britton-Robinson buffer (BR, pH=5.72). The fluorescence intensity of R6G had been increased sharply. Erythromycin diminished the fluorescence intensity of R6G. The detection limit was up to 0.316 mg l⁻¹. The range of determining concentration of erythromycin was 0.75-15 mg l⁻¹. The relative standards deviation were 0.66-1.38% for six parallel determinations of erythromycin. The recoveries of erythromycin were 96.95-101.41%. The measurement was applied to the determination of capsules of erythromycin with good results.     

Static and Dynamic Quenching of Tryptophan Fluorescence in Various Proteins by a Chromium (III) Complex

The interaction of a chromium (III) complex, (R,R)-N,N′-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diaminochromium (III), with human serum albumin, bovine serum albumin, lysozyme, and free tryptophan was studied using steady-state fluorescence spectroscopy. Dynamic and static quenching constants were calculated using Stern-Volmer kinetics. The complex bound more tightly to the serum albumins than to lysozyme or free tryptophan, but only one binding site was determined in all systems. The interaction was also determined to be thermodynamically favorable, and the binding constants were on the order of 10³–10⁶. The fluorescence quenching was static in nature with Forster distances in the 1.8–2.0 nm range.     

Fluorescence sensor for Cu(II) based on R6G derivatives modified silicon nanowires

A fluorescence sensor for selective detection of Cu(II) is realized by covalently immobilizing derivatives of rhodamine6G (R6G) on the surface of silicon nanowires (SiNWs). It features the release of R6G from the SiNWs in the presence of Cu(II), which causes a significant enhancement of the fluorescence over other metal ions. The present Cu(II) sensor has good selectivity and sensitivity, and exhibits a linear response in the range of 0.0-7.0 μM Cu(II). Different from conventional Cu(II) sensor with fluorescence quenching, the present sensor based on fluorescence enhancement facilitates the practical application. Especially, the release of the R6G from SiNWs could be utilized as fluorescent labeling for Cu(II) in microenvironment.     

银/硅纳米孔柱阵列活性基底的SERS效应研究

以硅纳米孔柱阵列(Si-NPA)为衬底,采用浸渍法制备出一种具有规则表面形貌特征的银/硅纳米孔柱阵列(Ag/Si-NPA),并以R6G为探测目标材料,对其表面增强拉曼(SERS)效应进行了研究。结果表明,对于R6G浓度低至10-15M,Ag/Si-NPA均能表现出清晰的特征SERS峰。随着浓度的降低,R6G的荧光淬灭,所测拉曼光谱的基线降低,但特征峰峰位基本保持不变。在低浓度10-15M时得到的SERS光谱,理论上证明为单分子光谱。此外,Ag/Si-NPA活性基底具有较好的稳定性,在长达28天的自然老化过程中,Ag/Si-NPA能够保持对R6G较高的探测水平,光谱具有较好的信噪比和分辨率。Ag/Si-NPA是一种理想的SERS活性基底。     

Rotamer-specific fluorescence quenching in tyrosinamide: Dynamic and static interactions

We have examined the environments of the three phenol rotamers about the C–C bond in tyrosinamide by fluorescence quenching. Steady-state acrylamide quenching yields a nonlinear stern-Volmer plot. With three distinct emitting species and no other information about the system, it is impossible to analyze the data due to the number of variables which have to be determined. We therefore reduced the number of variables by independently determining the fractional intensity and dynamic quenching constant for each rotamer through time-resolved fluorescence quenching studies. These parameters were then used to analyze the steady-state data for any contribution of static quenching. We conclude that the nonlinear Stern-Volmer plot for the quenching of tyrosinamide by acrylamide is a consequence of each rotamer having a distinct dynamic quenching constant and the presence of static quenching. The static quenching can be represented by either the sphere-of-action model involving two of the three rotamers or the ground-state complex model involving all three rotamers.     

Combined Quenching Mechanism of Anthracene Fluorescence by Cetylpyridinium Chloride in Sodium Dodecyl Sulfate Micelles

The Stern-Volmer quenching constant (K_SV) for quenching of anthracene fluorescence in sodium dodecyl sulfate (SDS) micelles by pyridinium chloride has been reported previously to be 520 M^?1 based on steady state fluorescence measurements. However, such measurements cannot distinguish static versus dynamic contributions to the overall quenching. In the work reported here, the quenching dynamics of anthracene in SDS micelles by cetylpyridinium chloride (CPC), an analogue of pyridinium chloride, were investigated using both steady state and time resolved fluorescence quenching. Concurrent measurement of the decrease in fluorescence intensity and lifetime of anthracene provide a quantitative evaluation of collision induced (i.e. dynamic) versus complex formation (i.e. static) quenching of the anthracene fluorophore. The results reveal that a combined quenching mechanism is operative with approximately equal constants of 249?±?6 M^?1 and 225?±?12 M^?1 for dynamic and static quenching, respectively.