一种新的磺酸吲哚菁染料的荧光光谱分析及其应用研究

研究了一种新型磺酸吲哚菁染料的荧光光谱并应用于蛋白质分析.结果表明,随着染料浓度增大,染料发生J聚合,荧光峰从564nm红移至605nm.当染料处于较低浓度时,离子强度影响不明显,而在较高浓度,J聚合增强,荧光增强变化明显;乙醇有机试剂显著增强染料荧光,并发生红移.应用于蛋白质分析,染料荧光强度随牛血清蛋白BSA或人血清蛋白HSA的增加而显著增强,在最优条件下,染料荧光强度与蛋白质浓度成良好线性关系,BSA线性范围为0.20-6.00μg/mL,检出限为0.08μg/mL;HSA线性范围为0.20-6.00μg/mL,检出限为0.1μg/mL.     

准波导结构下染料薄膜的荧光光谱和放大自发辐射光谱特性

通过对RhB/PMMA和Rh6G/PMMA染料薄膜的荧光光谱和放大自发辐射(ASE)光谱的实验测量和理论分析,研究了准波导结构染料薄膜的荧光光谱和ASE光谱特性。实验上采用连续激光和脉冲激光照射,分别测量准波导结构RhB/PMMA和Rh6G/PMMA染料薄膜的荧光光谱和ASE光谱,发现荧光峰和ASE峰随着染料掺杂浓度和薄膜厚度的增加产生红移;理论上考虑准波导结构下薄膜中染料的自吸收效应,类比激光器谐振腔模型,分析低阶导模传输的增益特性,获得了荧光光谱与ASE光谱中荧光峰和ASE峰对应波长与染料掺杂浓度的关系,数值计算与实验测量相吻合。结果表明,准波导结构下薄膜中染料自吸收效应导致荧光峰及ASE峰发生红移,改变染料掺杂浓度,可以在较大调谐范围实现ASE。     

染料分子SERS与FTIR—Raman的比较研究

本文研究了强荧光染料罗丹明Ｂ（ＲｈＢ）的表面增强拉曼（ＳＥＲＳ）和傅里叶变换红外拉曼光谱，比较了这两种技术在研究荧光物质拉曼效应方面各自的特点和优势，并对两种方法获得的振动模式的差异及ＲｈＢ在银表面的吸附方式进行了讨论。     

多孔硅吸附染料分子的荧光增强效应

报道了利用多孔硅独特的表面特性,吸附染料分子后,使得染料的荧光得到很大的增强,并观察到了这种吸附过程中彼此间的能量转移过程。对染料的荧光增强机理及实验结果进行了讨论。     

染料分子SERS与FTIR－Raman的比较研究

本文研究了强荧光染料罗丹明Ｂ（ＲｈＢ）的表面增强拉曼（ＳＥＲＳ）和傅里叶变换红外拉曼（ＦＴＩＲ－Ｒａｍａｎ）光谱，比较了这两种技术在研究荧光物质拉曼效应方面各自的特点和优势，并对两种方法获得的振动模式的差异及ＲｈＢ在银表面的吸附方式进行了讨论。     

染料在聚乙二醇介质中的荧光光谱和溶剂效应研究

本文研究了激光染料Ｃｏｕｍａｒｉｎ－４８０，Ｏｘａｚｉｎｅ－７２０，Ｏｘａｚｉｎｅ－７２５在聚乙二醇介质中的荧光光谱。结果表明荧光光强度随着聚乙二醇浓度的不断增大而增强，荧光发射的最大峰位有较明显的红移，表明染料分子与聚乙二醇分子间形成了分子缔合物，缔合物愈稳定，荧光强度增强愈大，红移愈大。     

三氮吲哚Li嗪对增感染料吸收光谱和荧光谱的影响

本文研究了三氮吲哚Ｌｉ嗪（ＴＡＩ）对三种卤化银乳剂增感染料水溶液的吸收光谱和荧光光谱的影响，研究表明ＴＡＩ能使这些染料的各吸收峰强度增强，对容易形成了Ｊ聚集体的染料来说，更有利于其Ｊ态光谱吸收；当三氮吲哚Ｌｉ嗪的浓度达到一定值后，它能侃染料Ｈ聚集体分解成单分子，利用单分子光谱吸收，结果说明染料的荧光发射也随溶液中ＴＡＩ浓度的增大而增强，本文还讨论了产生这种现象的原因。     

三氮吲哚嗪对增感染料吸收光谱和荧光谱的影响

本文研究了三氮吲哚嗪（ＴＡＩ）对三种卤化银乳剂增感染料水溶液的吸收光谱和荧光光谱的影响。研究表明ＴＡＩ能使这些染料的各吸收峰强度增强，对容易形成Ｊ聚集体的染料来说，更有利于其Ｊ态光谱吸收；当三氮吲哚嗪的浓度达到一定值后，它能使染料Ｈ聚集体分解成单分子，利于单分子光谱吸收；结果说明染料的荧光发射也随溶液中ＴＡＩ浓度的增大而增强。本文还讨论了产生这种现象的原因。     

基于银掺杂钠钙玻璃的荧光染料自发辐射增强

本文通过离子交换和后续热处理的方法在钠钙玻璃中引入Ag纳米颗粒, 并将Ag掺杂的钠钙玻璃作为衬底增强了钠钙玻璃和荧光染料罗丹明6G(R6G)的荧光辐射。Ag纳米颗粒的表面等离激元散射增强了掺杂玻璃的荧光, 而R6G的增强荧光辐射则源于掺杂玻璃与荧光染料之间的辐射共振能量转移。     

机械抛光铜金属表面对罗丹明的荧光增强效应

应用激光光谱学方法,研究了铜表面Rh6G分子的荧光增强效应对于金属衬底表面所形成的氧化层的依赖关系,探索了由于空气氧化而形成的氧化层在表面荧光增强效应中的重要意义和作用机理.实验采用罗丹明6G荧光探针分子,在532nm连续光激发下,研究机械抛光铜金属衬底在经历不同氧化时间,对吸附其表面的Rh6G分子的荧光增强效果.研究结果表明,适当控制金属样品表面的氧化时间,金属铜表面对若丹明分子的荧光发射表现出猝灭和增强效应.金属氧化层起到了隔离荧光分子与金属表面的作用,减弱了由于激发态荧光分子向金属转移非辐射能量和在金属表面诱导反向偶极子而产生的荧光猝灭效应,从而提高了纯金属铜表面荧光增强辐射行为.因此在微纳金属衬底的荧光增强效应研究中,采用适当的实验手段,精确控制隔离层间距,是表面增强光谱获取的重要途径之一.     

Correlation between photophysical properties and lasing performances of Rhodamine-19 in three types of sol–gel glass hosts

Rhodamine-19 (Rh-19) incorporated three types of sol–gel samples (mentioned as dope route-I, dope route-II and dip method) were prepared by using two different methods of dye impregnation. The photophysical properties of all the three types of Rh-19 incorporated sol–gel solids were studied by using the UV–Visible absorption and the fluorescence spectroscopy. A single photon counting technique was used to estimate the lifetime of fluorescent species. From the study of fluorescence spectra, the coexistence of dimers (fluorescent and non-fluorescent both) and monomer of Rh-19 was observed. The photophysical properties of Rh-19 were found to be the best in dip sample, medium in dope route-II sample and low in dope route-I sample. After studying photophysical properties, the samples were subjected to laser study under nitrogen laser pumping at 337.1 nm at the rate of 1.5 Hz in transverse dye laser cavity. The highest laser efficiency and photostability of the dye were observed in dip sample, medium in dope route-II sample and small in dope route-I sample. A comparison between photophysical properties and laser performance of these materials showed a very good correlation.     

SDS增溶DCM水溶液的荧光特性研究

研究了十二烷基硫酸钠(SDS) 增溶DCM水溶液的荧光光谱特性。随着SDS浓度的增加, DCM在水中的溶解度大大增加,荧光强度增强;当SDS浓度从0.025 mol·L-1增加到0.5 mol·L-1时,荧光峰值相对强度增强95倍。用532 nm激光激发SDS增溶DCM水溶液获得648 nm的强染料激光输出, 其波长相对于由DCM乙醇溶液获得的635 nm染料激光红移13 nm。利用该溶液荧光对苯的受激拉曼散射(SRS)Stokes波长选择增强。作为对比,用DCM乙醇溶液的荧光对苯受激拉曼散射进行选择增强,结果显示出二者对苯的二、三、四阶Stokes波均可产生放大,但前者最大放大波长位于第三阶Stokes线(632 nm)处,放大因子8.5,后者最大放大波长位于第二阶Stokes线(595 nm)处,放大因子为2.5。另外分析讨论了SDS增溶DCM水溶液和荧光增强的机制及其应用前景。     

Stilbene 420激光染料的光谱特性分析

配制了Stilbene 420染料溶液。测量了其吸收光谱。以调Q倍频Nd∶YAG激光为抽运源,实现了对Stilbene 420染料的激光光谱和荧光光谱的分析。激光光谱在425 nm处获得最强峰值,半峰高宽(FWHM)为1 nm,光谱范围为420～440 nm。荧光光谱峰值在428.5 nm,与激光最强峰值相差3.5 nm。最高染料转换效率为9.26%。     

Influence of surfactants on the fluorescence and absorption spectra of erythrosin in aqueous solution

The effect of certain non-ionic, anionic and cationic surfactants on the fluorescence and absorption spectra of erythrosin has been studied. Shifts towards longer wavelengths in absorption and fluorescence peaks have been observed. Also, there appears to be a marked enhancement in the fluorescence intensity of erythrosin on adding small amounts of surfactants. The shift in the absorption peak wavelength appears to be due to the binding of the surfactant with dye molecules. The enhancement in the fluorescence intensity is attributed to the disaggregation of erythrosin dye dimer and multimer forms into the monomeric form. The change in the geometry of dye molecules in the presence of cationic surfactants has also been discussed. Enhancement in the fluorescence intensity on the addition of ethanol has been observed.     

染料掺杂聚合物薄膜中金纳米颗粒增强的随机激光

基于金属纳米结构而获得随机激光的增强,其独特的性质及其潜在的应用价值具有重要的研究意义,在表面增强荧光、光学开关器件、表面等离子激元激光等方面实现了较多应用。报道一种快捷有效的制备纳米颗粒的手段并基于该纳米颗粒结构分析了染料掺杂聚合物薄膜涂覆的随机激光现象和规律。利用离子溅射沉积和高温热处理在石英基底上制备了Au纳米颗粒,改变溅射时间Au纳米颗粒的尺寸发生可控变化,该方法便捷、工艺简单。研究采用40,80和120 s三种不同的时间进行Au膜溅射并在650 ℃下高温处理,得到粒径尺寸不同的Au纳米颗粒,随着溅射时间延长Au纳米颗粒的尺寸逐渐变大。通过涂覆有机荧光染料DCJTB掺杂的PMMA聚合物薄膜构建光致激射系统,利用纳秒脉冲激光对样品进行激发,得到随机激光并研究其出射光强度和阈值的变化规律特征。40,80和120 s三种溅射时间下所得Au纳米颗粒的平均粒径尺寸分别为230,250和390 nm,在532 nm激光激发下产生随机激光的阈值分别为20.5,17.5和12.5 μJ·pulse-1。Au纳米颗粒尺寸越大、粒子间距越小时,光子散射的平均自由程越短,光在金属颗粒之间可以多次有效散射,从而显著提高散射效率,产生较低阈值的激光发射;Au纳米颗粒的吸收峰与染料的荧光峰恰好匹配时,将会显著增强染料的荧光效应,激发更多染料分子发生能级跃迁,增加光子态密度,获得峰值更高、阈值更低的激射现象;泵浦光不破坏染料分子的情况下,可以多次循环泵浦获得激光,染料分子的发光效率随着多次激发略有降低,有助于随机激光器件的研究开发。实验研究结果与理论分析相一致,进一步明确了Au纳米颗粒对光子散射和等离子共振对光吸收增强的随机激光发射机理。该研究以Au纳米结构对光子的强散射效应为增益,通过理论分析和实验测量获得随机激光,为实现高效率、低阈值的随机激光研究提供了一种便捷的技术手段,有望促进随机激光器件的开发和应用。     

Fluorescence Study of DNA–Dye Complexes Using One-Photon and Two-Photon Picosecond Excitation

Preliminary results of investigation of one-photon- and two-photon-induced fluorescence of acridine orange (AO), epirubicin (ER), hypericin (HYP), and ethidium bromide (EB) in complexes with DNA are presented. A spectrofluorometer based on a picosecond Nd:YAG laser was used for investigations of two-photon (1064-nm, 1-mJ, 40-ps) and one-photon (532- and 355-nm) dye excitation. The spectra of two-photon-induced fluorescence of dyes and their complexes with DNA as well as the kinetics of dyes' fluorescence intensification during their interactions with DNA in dependence on the biomacromolecule concentration were obtained. The intensities of AO, HYP, and EB fluorescence were increased 2.4, 3.2, and 8 times, respectively, after binding with DNA at two-photon excitation, while at one-photon excitation the corresponding values were 2.5, 3.7, and 10 times. The difference in fluorescence enhancement during DNA–dye complex formation at linear and nonlinear excitation may possibly be associated with the fact that the cross sections of one-photon and two-photon absorption, in general, change unequally during the binding of dyes to organic molecules and bathocromic shift of the electronic transitions. It was shown that the peak of AO fluorescence shifted to a longer wavelength on 10 nm after two-photon excitation at 1064 nm in comparison with one-photon excitation at 532 nm.     

Efficient lasing action from Rhodamine-110 (Rh-110) impregnated sol-gel silica samples prepared by dip method

Rhodamine-110/sol-gel samples are prepared by sol-gel technique using dip method. Concentration dependent photophysical studies of these samples have indicated about the least possibility of aggregate formation. The lasing action of Rh-110 in silica samples is studied as a function of dye concentration. An efficient laser emission is observed when the samples are transversely pumped at 337.1 nm and 1.5 Hz repetition rate using a nitrogen laser (400 μJ energy/pulse and 4 ns pulse duration). The maximum of 166% laser efficiency of dye doped sol-gel samples compared to Rhodamine-6G (Rh-6G) in methanol is achieved. The photostability is also measured by using N₂ laser at 1 Hz and it is found nearly 165 pulses. The possible reasons for the photodegradation of the dye molecules are discussed in detail.     

Optical bistability in fluorescein dyes

Optical bistability has been observed in highly concentrated fluorescein dye solutions and in thin (1 m) doped polymeric films. At concentrations larger than 10^–5 mole/l dye dimers are formed. For fluorescein dye, the dimer-monomer equilibrium constant is 10⁵ l/mole so that most of the dye species are in the dimer form. At 480 nm the dimer absorption cross section is 10^–18 cm²/molecule, while that for the dye monomer molecule is 7.6×10^–17 cm²/molecule. Upon laser excitation dimers dissociate to form monomers thus providing a highly nonlinear laser induced absorption. This high nonlinear absorption coefficient can be utilized for optically bistable response of the dye system.Optical bistability was observed by placing dye solutions or dye thin films inside a Fabry-Perot resonator and exciting it with 480 nm dye laser pulses of 10 ns duration. The effect is more pronounced in 10^–4 mole/l fluorescein than in 10^–6 mole/l fluorescein in which dimer formation is not that efficient.In disodium fluorescein no significant dimer formation is observed even at 10^–3 mole/l dye concentration. The observed bistability both in solution and in thin films can be explained in terms of recent models for optical bistability in nonlinearly absorbing molecular systems.     

The molecular aggregation of pyronin Y in natural bentonite clay suspension

The molecular aggregation and spectroscopic properties of Pyronin Y (PyY) in the suspension containing natural bentonite clay were studied using molecular absorption, steady-state and time-resolved fluorescence spectroscopy techniques. Interaction between the clay particles and the cationic dye compounds in aqueous solution resulted in significant changes in spectral properties of PyY compared to its molecular behavior in deionized water at the same concentration. These changes were due to the formation of dimer and aggregate of PyY in the clay suspension as well as the presence of the dye monomer. The H-type aggregates of PyY in the clay suspension were identified by the observation of a blue-shifted absorption band of the dye compared to that of its monomer. In spite of diluted dye concentrations, the H-aggregate of PyY in the clay suspension was formed. The intensive aggregation in the clay suspension attributed to the localized high dye concentration on the negatively charged clay surfaces. Adsorption sites of PyY on the clay particles were discussed by deconvulated absorption and excitation spectra. Fluorescence spectroscopy studies revealed that the fluorescence intensity of PyY in the clay suspension is decreased by H-aggregates drastically. Moreover, the presence of H-aggregates in the clay suspension resulted in the decrease of fluorescence lifetime and quantum yield of PyY compared to those in deionized water.     

Investigation of the spontaneous emission rate of perylene dye molecules encapsulated into three-dimensional nanofibers via FLIM method

The decay dynamics of perylene dye molecules encapsulated in polymer nanofibers produced by electrospinning of polymethyl methacrylate are investigated using a confocal fluorescence lifetime imaging microscopy technique. Time-resolved experiments show that the fluorescence lifetime of perylene dye molecules is enhanced when the dye molecules are encapsulated in a three-dimensional photonic environment. It is hard to produce a sustainable host with exactly the same dimensions all the time during fabrication to accommodate dye molecules for enhancement of spontaneous emission rate. The electrospinning method allows us to have a control over fiber diameter. It is observed that the wavelength of monomer excitation of perylene dye molecules is too short to cause enhancement within nanofiber photonic environment of 330 nm diameters. However, when these nanofibers are doped with more concentrated perylene, in addition to monomer excitation, an excimer excitation is generated. This causes observation of the Purcell effect in the three-dimensional nanocylindrical photonic fiber geometry.