掺铒铋酸盐玻璃和掺铒碲酸盐玻璃的荧光俘获和浓度猝灭效应

用高温熔融法制备了系列掺铒铋酸盐和碲酸盐玻璃,用分光光度计测试吸收光谱,并用荧光光谱仪测试了不同铒离子掺杂浓度时玻璃样品的荧光光谱和荧光寿命.结果显示:掺铒后,铋酸盐玻璃和碲酸盐玻璃中存在着强烈的荧光俘获和浓度猝灭效应.随着玻璃中铒离子掺杂浓度的增加,1.53 μm波段荧光谱展宽,1 560 m波长处荧光次峰增强,但相对于铋酸盐玻璃,碲酸盐玻璃具有更为强烈的荧光俘获效应.同时,随着铒离子掺杂浓度的增加,4I13/2能级荧光寿命和1.53 μm波段荧光强度呈先增加后减小趋势.根据Dexter能量转移理论,计算并分析比较了这2种宽带玻璃系统中铒离子发生浓度猝火的临界距离R0及相互作用参数Cer-Er.     

稳态荧光光谱法分析超氧化物岐化酶溶液的稳定性

目的考察超氧化物岐化酶(SOD)溶液在不同影响因素下的活性及构象变化。方法通过邻苯三酚自氧化速率法测定SOD溶液的活性,利用稳态荧光光谱法分析在不同影响因素(pH值、超声、变性剂盐酸胍)下SOD三、四级结构的变化与荧光光谱特征变化的关系。结果溶液pH值降低,SOD稳定性增加;在pH2.2～pH7.0的范围内,pH值与SOD比活力呈线性相关;随着pH值的降低,普通荧光最大发射波长由336nm蓝移至325nm。超声次数的增加使同步光谱谱带蓝移,SOD活性下降。随着盐酸胍浓度的升高,SOD活性逐渐下降;在盐酸胍浓度达2.1mol/L时,SOD最大荧光发射峰蓝移至312nm;经盐酸胍变性后,酶的荧光强度比天然态酶有所增加。结论采用稳态荧光光谱法可分析SOD溶液的稳定性。     

吖啶橙受溶液pH和浓度变化的光谱研究

利用荧光光谱分析仪研究吖啶橙受溶液pH和浓度变化的吸收光谱和荧光光谱的变化。实验表明,当改变吖啶橙溶液pH和浓度时,它的吸收光谱和荧光光谱发生位移。吖啶橙为1×10-6mol/L时,不同pH的吖啶橙溶液均在(490±3)nm出现一个强吸收峰,pH=6.5,吸收光谱的λm ax=430 nm,发生蓝移;而荧光光谱的λm ax随pH增大发生红移,荧光强度减弱。在浓吖啶橙溶液中,不同pH的吖啶橙溶液的吸收光谱的形状基本相同,出现两个吸收峰,λm ax1分别为(455±3)nm和(430±3)nm,λm ax2分别为(505±4)nm和(510±2)nm,吸收光谱红移;荧光光谱的λm ax均为(535±2)nm,荧光强度荧光很弱。pH相同或相近时,吖啶橙溶液的吸收光谱蓝移和荧光光谱红移,浓度越大,荧光强度越弱。还探讨了吖啶橙在水溶液中的赋存状态,结果表明,在稀溶液中,吖啶橙主要以单体的形式存在;在高浓度吖啶橙溶液中则以吖啶橙单体、二聚体,甚至多聚体形式存在。这说明溶液pH主要影响到吖啶橙分子基态的质子化和氢键的形成能力,使得分子的基态与激发态之间的能量间隔发生了变化,吖啶橙被质子化,则引起发光光谱向短波方向移动,而离解作用,则引起发光光谱向长波方向移动;吖啶橙浓度变化影响吖啶橙在水溶液赋存状态,引起吸收光谱向短波方向移动或向长波方向移动。     

可溶性镍酞菁的光谱特性研究

利用UV－Vis吸收光谱、荧光光谱及半经验ZINDO／S方法，研究了4种可溶性镍酞菁（FPcNi,MePcNi,iBPcNi,iPPcNi)的电子吸收光谱和荧光光谱。研究结果表明：随着取代基的供电子能力增加，酞菁的最大吸收波长（λmax)和发射波长（λem）发生红移，摩尔消光系数变小；随着溶液浓度增大，酞菁聚集体浓度增大，λmax发生蓝移，但浓度对λem影响较小，同时荧光相对强度随浓度增大，出现最大值；随着溶剂配合能力的增加，λmax，λem都发生红移。     

纳米银对荧光染料曙红的荧光猝灭效应

在较高温度下制备了平均粒径约为100 nm的胶态纳米银,研究了在水溶液条件下其对荧光染料曙红荧光性能的影响.发现不同浓度的纳米银与荧光素溶液作用后可使荧光强度减弱,并且其猝火效成随纳米银粒子粒径的减小、纳米银浓度的增加而增大.同时发现溶液pH的升高可使该体系荧光猝灭减小.并从分子结构及纳米银表面局域场和无辐射通道等方面对荧光强度变化的原因作了讨论.     

水环境中溶解态腐殖酸与Pb^2＋络合的荧光特性研究

通过三维激发波长-发射波长-荧光强度矩阵荧光光谱(3DEEMS)的荧光等高线和发射荧光谱图研究溶解态腐殖酸及其与铅离子络合的荧光特性.结果表明,腐殖酸分子中主要存在两类能够发射荧光的有机物官能团,受pH、溶液离子强度影响,其中荧光峰A所代表的有机物官能团受这两种因素影响尤为显著.腐殖酸分子与Pb2+作用结果说明,荧光峰B所代表的有机物官能团是与Pb2+络合的主要点位,且该点位对Pb2+具有较强的络合能力.荧光峰A所代表的有机物官能团与Pb2+络合较弱,受溶液离子强度影响显著.     

一步法水相制备Cu–In–Zn–S量子点及其荧光性能

采用简单的一步法制备了水溶性Cu–In–Zn–S (CIZS)四元量子点,利用X射线衍射仪、透射电子显微镜和荧光光谱仪等测试手段研究了反应温度、阳离子浓度和前驱体溶液pH值对样品的物相组成、显微形貌以及荧光性能的影响规律。结果表明:随着反应温度的升高,量子点的结晶度逐渐提高,荧光强度显著增强,当反应温度为95℃时,荧光强度达到了最高值;随着阳离子浓度的逐渐增大,量子点的粒径逐渐减小,导致其发光峰位由634 nm蓝移至617 nm,当阳离子浓度为1.5 mmol/L时,量子点的荧光强度最高。此外,当溶液pH值=5.0时,配体对量子点的表面钝化效果最佳,荧光强度达到最高值。红外光谱表明,量子点表面存在多种功能基团,赋予了量子点优异的水溶性,因此在生物成像领域具有广阔的应用前景。     

pH灵敏化合物的合成及其光谱性能

以醛酮缩合原理,设计并合成了2,5-双(4-羟基-苯亚甲基)环己酮,研究发现其溶液的光谱性能对pH值有一定的依赖性。化合物的紫外吸收光谱强度随着溶液的pH变化,而当溶液体系由酸性变为碱性时,紫外吸收光谱发生红移,表现出的结果就是溶液颜色发生变化。化合物的荧光光谱强度,在碱性条件下pH值的增加有20倍以上的增大。研究表明该化合物可作为pH的探针使用。     

风化煤中腐植酸的提取及其光谱学研究

探讨了从风化煤中提取棕腐酸和黑腐酸的方法,分别用紫外可见光谱、傅立叶变换红外光谱和三维荧光光谱对提取的腐植酸进行了表征,并说明了两种腐植酸结构上的差异.结果表明,棕腐植酸和黑腐植酸官能团种类相似,但含量总体是棕腐酸高于黑腐酸.两种腐植酸的紫外可见光谱在整个区间的吸光度是随着波长的增大而减小的混合光谱.两种腐植酸都有荧光效应,且无论随着浓度增加或者pH值增加,棕腐植酸和黑腐植酸的发光峰都有红移现象.     

药根碱与牛血清白蛋白相互作用的光谱研究

采用荧光和UV光谱法研究了盐酸药根碱(Jat)与牛血清白蛋白(BSA)相互作用的光谱特性.结果表明:Jat对于BSA荧光猝灭主要是静态猝灭和非辐射能量转移;Jat浓度增大,BSA荧光峰被猝灭的同时出现峰裂分现象,原来345 nm处的单峰逐渐裂分为二重峰,其中一峰峰值蓝移,另一峰峰值红移至λcm=362～365 nm;测...     

荧光素在明胶片中的光吸收及稳定性

由于对非线性光学材料的需求,近年来已有很多工作对荧光素的光学及光化学性质进行研究,研究对象既有溶液也有聚合物薄膜。 本工作使用明胶片研究荧光素在明胶片中的光吸收、荧光及光稳定性。     

The fluorescence of dihydroxyphenylalanine: the effects of protonation-deprotonation

The fluorescence excitation and emission spectra and quantum yields of 3,4-dihydroxyphenylalanine (DOPA), its methyl ester (DOPAM) and the N -acetylated derivative (DOPANA) in aqueous solution at pH values ranging from 3.0 to 10.0 have been determined and the excitation spectra related to their absorption spectra. The fluorescence quantum yield of the phenolic form of DOPA is 0.09. However, the fluorescence yield is substantially reduced for the conjugate base forms, i.e. deprotonation of the amine group and the phenolic hydroxyl group. The fluorescence spectra are dominated by the phenolic forms of DOPA, DOPAM and DOPANA from pH 3.0 to 10.0 with excitation and emission spectral maxima at 280 and 315 nm respectively. The excitation maxima for all the compounds correspond to the absorption maxima of their phenolic forms. The phenolate anions of DOPA and DOPAM exhibit weak fluorescence with emission maxima at 325 and 330 nm respectively.     

Bright two-photon emission and ultra-fast relaxation dynamics in a DNA-templated nanocluster investigated by ultra-fast spectroscopy

Metal nanoclusters have interesting steady state fluorescence emission, two-photon excited emission and ultrafast dynamics. A new subclass of fluorescent silver nanoclusters (Ag NCs) are NanoCluster Beacons. NanoCluster Beacons consist of a weakly emissive Ag NC templated on a single stranded DNA ("Ag NC on ssDNA") that becomes highly fluorescent when a DNA enhancer sequence is brought in proximity to the Ag NC by DNA base pairing ("Ag NC on dsDNA"). Steady state fluorescence was observed at 540 nm for both Ag NC on ssDNA and dsDNA; emission at 650 nm is observed for Ag NC on dsDNA. The emission at 550 nm is eight times weaker than that at 650 nm. Fluorescence up-conversion was used to study the dynamics of the emission. Bi-exponential fluorescence decay was recorded at 550 nm with lifetimes of 1 ps and 17 ps. The emission at 650 nm was not observed at the time scale investigated but has been reported to have a lifetime of 3.48 ns. Two-photon excited fluorescence was detected for Ag NC on dsDNA at 630 nm when excited at 800 nm. The two-photon absorption cross-section was calculated to be ～3000 GM. Femtosecond transient absorption experiments were performed to investigate the excited state dynamics of DNA-Ag NC. An excited state unique to Ag NC on dsDNA was identified at ～580 nm as an excited state bleach that related directly to the emission at 650 nm based on the excitation spectrum. Based on the optical results, a simple four level system is used to describe the emission mechanism for Ag NC on dsDNA.     

Fluorescence upconversion properties of a chiral polybinaphthyl induced by two‐photon absorption

The fluorescence properties of a chiral polymer based on optically active polybinaphthyls were studied in tetrahydrofuran solution. One‐photon excited fluorescence of the polymer was located in the range of ～ 596 nm and the corresponding lifetime was ～ 4.38 ns. From the excitation spectra and emission spectra excited at 800 nm, the upconversion fluorescence emission was observed. When excited by using 800 nm fs laser pulses with different input irradiances, the peak fluorescence intensity of the solution provides square dependence with the input irradiance power, giving an evidence for two‐photon excited fluorescence. Furthermore, open aperture Z‐scan measurements were performed at different irradiation intensities to confirm two‐photon absorption property of the solution at 800 nm excitation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

2种不同激光对钛宝石辐照作用的研究

分别采用波长为193 nm的ArF准分子激光与波长为800 nm、脉冲宽度为120 fs的飞秒激光对温梯法生长的钛宝石进行辐照,并对辐照前后的吸收谱、荧光谱及电子顺磁共振(EPR)谱进行了检测。2种不同辐照的结果表明:218 nm及266 nm吸收峰并不是完全由同一种色心所引起的。通过对比不同品质因数(FOM)值的钛宝石样品在420 nm处的荧光谱,发现准分子激光辐照后420 nm处荧光强度降低,表明样品中Ti~(4 )离子浓度降低。而在飞秒激光辐照下荧光强度增大,即Ti~(4 )浓度增大。根据2种激光的波长,功率密度及辐照方式的差异对于2种辐照产生不同结果做出了解释。     

Fluorescence quenching of poly(methylphenylsilane) in solution

The solution, electron-transfer fluorescence quenching of a typical aromatic polysilane[poly(methylphenylsilane)] by a series of electronic deficient aromatic monomers is described. The rate of fluorescence quenching is a function of the reduction potential of the quencher, and only very fast processes can be observed, due to the short polymer fluorescence lifetime. The measurement of quenching rate constants, which are considerably larger than diffusion control, suggests that extensive energy migration occurs in the polymer. Although the fluorescence quenching at low quencher concentrations follows Stern-Volmer kinetics, at high concentrations, contributions from static quenching are apparent. Strong fluorescence quenching can either accelerate or inhibit photodegradation, depending on the structure of the quencher.     

Absorption and fluorescence of soluble polar diketo-pyrrolo-pyrroles

Six soluble derivatives of 3,6-diphenyl-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione N-alkylated on pyrrolinone ring with polar substituents in para positions of pendant phenyl rings were synthesized; five of them are reported for the first time. Absorption and fluorescence spectra were studied in solvents of different polarity. The compounds show small solvatochromism of absorption and a moderate positive solvatochromism of fluorescence, especially when substituted by strong electron-donating piperidino substituent. A significant decrease of fluorescence quantum yields and its biexponential decay for dipolar derivatives in polar solvents was tentatively ascribed to the formation of twisted intramolecular charge transfer (TICT) excited state. All six compounds show fluorescence in polycrystalline solid-state with the maxima covering a range over 200 nm in visible and near infrared region.     

含钐稀土三元有机配合物的合成及荧光性能表征

在稀土离子钐中掺入钇,以水杨酸、邻菲咯啉为有机配体合成了一系列的新的三元有机配合物,研究了该系列配合物的荧光性能,并从中探讨了荧光性能随掺杂离子Y的变化规律,结果表明,稀土离子Y的掺入能改变Sm的红光发光强度,在70％含量时达到最佳。Sm-Y系列有机配合物的特征发射峰位于565、600和650nm处,与植物叶绿素光合作用的吸收红光波段吻合性较好。