A STUDY OF NOVEL NEAR INFRARED LASER DYES WITH TUNING RANGE FROM 70O TO 900 nm

In this paper, the characteristics of three novel near infrared laser dyes withwide-tuning ranges and high conversion efficiency are reported. The tunable spectral regions ofthese dyes pumped by the second harmonic pulse(532nm)of Nd: YAG laser are from 700nmto 900nm with a conversion efficiency between 6.6% and 9.0%. The aborption spectraand fluorescence spectra of these dyes are also given.     

Benzotriazole-based dyes containing a low band gap for dye-sensitised solar cells: a theoretical study

In this study, we investigated a series of metal-free benzotriazole-based organic dyes. The geometries, electronic properties, light harvesting efficiency, and electronic absorption spectra of these dyes were studied using the density functional theory and time-dependent density functional theory. The optimised geometries indicate that these dyes are non-planar and thereby effectively inhibit close intermolecular π–π aggregation. The band gap of these dyes ensures a positive effect on the process of electron injection and dye regeneration. The band gap trend corroborates well with the predicted spectra data. Our theoretical calculations reveal that the designed metal-free organic dyes can be used as potential sensitisers for solar cells compared to the best known organic sensitiser (Y123) to date.     

Biscoumarins - New Laser Dyes in Coumarin Series

With a view to extend the tunability range using new derivatives in the coumarin series of dyes, a novel series have been synthesized, viz. the biscoumarins where two coumarin nuclei are coupled. These are studied for their lasing characteristics, optical spectra and quantum efficiencies. Laser spectra of these dyes in various solvents are also studied. Tunability range of these dyes have been found to cover blue green region of the spectrum and though there is shift to longer wavelength as compared to monocoumarins, extending the tunability range, it is not as much as would be normally expected with extended conjugation involving two coumarin nucled.     

一类菁染料的SERS光谱研究

本文报导了一类菁染料在银溶胶中和吸附在硝酸刻蚀的银和铜箔上的SERS 光谱以及两种方式的比较。对硝酸刻蚀粗化银和铜箔表面的最佳条件进行了讨论,区别于银溶胶,用粗化银和铜箔测得了共振 SERS 光谱。提出了菁染料分子在铜、银表面吸附的可能方式。     

Solvent Effects on the Spectroscopic Properties of Styrylquinolinium Dyes Series

The study on the relationship between the structure and spectroscopic properties of styrylquinolinium dyes were carried out by measuring the electronic visible absorption, steady-state and time-resolved fluorescence spectra of quinoline based hemicyanine dyes. The influence of the solvent on absorption and emission spectra and the solvatochromic properties, observed for both ground and first excited states, for all the dyes were applied for the evaluation of their excited state dipole moments. The ground state dipole moments of dyes under the study were established by applying ab initio calculations. The measured, using solvatochromic methods, excited state dipole moments of tested hemicyanines are in the range from 5.38 to 18.90 D and the change in the dipole moments caused by excitation were found to differ from 1.88 to 6.64 D. It was observed that for all tested dyes the dipole moments of the excited states were higher than those of a ground states. The fluorescence lifetime measurements with picosecond resolution was performed for entire series of hemicyanine dyes possessing different dialkylamino groups attached to the phenyl ring. The average lifetimes of the dye fluorescence, determined from the measured data by multi-order exponential decay curve fitting, were in the range from about 120 to 1200 ps at the fluorescence peak wavelength. The fluorescence lifetime measurements were performed for dyes in ethyl acetate solutions. The time-resolved fluorescence spectra measurements allowed to propose the mechanism of the dyes excited states deactivation.     

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。     

Spectral Characterization of Some Phenylazodihydroxy Naphthalene Derivatives

A series of azo dyes namely: 4-phenylazo-1,3-dihydroxynaphthalene 1, 4-phenylazo-1,5-dihydroxynaphthalene 2, 1-phenylazo-2,8-dihydroxynaphthalene 3, 1-phenylazo-2,3-dihydroxynaphthalene 4 and 1-phenylazo-2,7-dihydroxynaphthalene 5 have been prepared and their UV, IR, NMR and mass spectra are recorded. The spectra have been analysed to give a complete picture of the hydroxyazo-quinone hydrazone tautomerism present in these class of compounds. It is found that dyes 1, 2 and 4 exhibit quinone hydrazone tautomerism while dyes 3 and 5 exist as a mixture of hydroxyazo and quinone hydrazone tautomers. The change due to a second hydroxyl group in the naphthalene moiety is compared with azonaphthols. The fragmentation process in the mass spectra displays C-N and -N = N-cleavage and indicated that the two tautomers are present except in dye 2 which exhibits a quinone hydrazone form.     

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。     

Properties and the nature of electric-field-induced variations in optical absorption spectra of polymethine dyes in polymer matrices

The effect of a permanent electric field on the absorption spectra of ionic (cationic and anionic) and intraionic symmetric and asymmetric polymethine dyes in poly-N-epoxypropylcarbazole, polyvinylbutyral, and polystyrene polymer films is studied. It is found that the electric field causes an increase in absorption of symmetric dyes in the short-wavelength region and a decrease in their absorption in the long-wavelength region. Asymmetric dyes exhibit opposite properties. These properties are common for these groups of dyes irrespective of their chemical structure and ionic nature. They are retained both in photoconducting polymers and in polymers that are incapable of charge photogeneration. These effects also take place in liquid solutions, although in this case they are much weaker. Various mechanisms of the influence of an electric field on the spectra, such as the electron transfer, Stark and Kerr effects, intermolecular interactions, and dye isomerization, are discussed. It is shown that the spectral effects are caused by the redistribution of the electron density in a chromophore of the dye in the ground state resulting in a change in the probability of vibronic transitions.     

UV-spectral changes for some azo compounds in the presence of different solvents

The electronic absorption spectra of four azo dyes with different substituents (such as Cl, I, OH) are determined at room temperature in twenty-one solvents with different polarities. The electronic transitions of azo dyes are interpreted. Linear solvation energy relationships have been investigated for solvatochromic behaviors and solute-solvent interactions of azo dyes. Linear solvation energy relationships were performed by multiple linear regression analysis using dielectric function, refractive index function and Kamlet-Taft parameters. We have observed that the hydrogen bonding acceptor ability and the induction-dispersive forces of solvent molecules have caused the bathochromic shift in absorption maxima of azo dyes.     

Identification of tartrazine and sunset yellow by fluorescence spectroscopy combined with radial basis function neural network

The fluorescence spectra of synthetic food dyes of sunset yellow and tartrazine are analyzed. The fluorescence peak wavelengths of sunset yellow and tartrazine are 576 and 569 nm, respectively, while the fluorescence spectra widths are 480-750 and 500 750 nm induced by ultraviolet light between 310-400 nm. The fluorescence spectra of sunset yellow overlap heavily with those of tartrazine, so it is difficult to distinguish them. Based on the principle of radial basis function neural network, a neural network is obtained from the training of the 14 groups of experimental data. The results show that the species of sunset yellow and tartrazine could be recognized accurately. This method has potential applications in other synthetic food dyes detection and food safety inspection.     

Synthesis,Characterization and Fluorescence Studies of Novel Tetrachloroperylene-Azo Hybrid Dyes

Novel rylene-azo hybrid dyes have been synthesized by condensation of azo-dyes with tetrachloroperylene dianhydride, possessing stupendous thermal, chemical and photochemical stability. Phenolic azo dyes are used for the nucleophilic replacement of chlorine substituents at 1,6,7,12-positions of perylene 3,4,9,10-dianhydride system. The absorption maxima (?_max) of these dyes have been determined in diverse solvents such as water, ethanol, methanol, ethyl acetate and N, N-dimethylformamide. Fluorescence spectra are taken in water and highest fluorescence was exhibited by dyes containing carboxylic groups. The ?_max and fluorescence of these dyes is greatly affected by polarity of solvents. The structures of newly synthesized rylene-azo hybrid dyes have been confirmed by UV, FTIR and ¹HNMR spectroscopy.     

Spectral Properties of Single BODIPY Dyes in Polystyrene Microspheres and in Solutions

The absorption, fluorescence, fluorescence quantum yield, and photostability of five BODIPY dyes are characterized and compared as single dyes in two environments, in 40-nm polystyrene spheres and in solution. The absorption and fluorescence spectra of the dyes in spheres are similar in profile but shifted to lower energies compared to those in solution. All the dyes are highly fluorescent, with three having fluorescence quantum yields of 1.0. For three of the five dyes, the yields were the same in spheres as in solution (1.00, 1.00, and 0.73). The high concentration of these dyes in spheres does not quench their fluorescence. For two other dyes the yields dropped, from 1.00 to 0.55 in one case and 0.83 to 0.50 in another, comparing the dyes in solution versus in spheres. The photodegradation of the dyes decreases in spheres compared to in solution in all but one case. For one dye, it decreases as much as 800-fold. Dyes overlooked because of low fluorescence or stability in solution could become useful fluorescent materials in the microsphere environment.     

Quantum-chemical study of relation of spectral and luminescent properties of positively solvatochromic malononitrile-based merocyanine dyes with their structure

The electronic structure, the spectra, and the efficiency of photophysical processes of energy deactivation are calculated by a semiempirical method for three positively solvatochromic merocyanine dyes with different polymethine chain lengths. The electronic structure and spectra calculated by different modifications of the INDO method at different molecular geometries are compared, and the optimum geometry of the isolated molecule is chosen. The absorption spectra of dyes are interpreted, including the short-wave-length bands related to transitions to highest excited states. The possibility of a specific electrophilic solvation of these compounds in the ground and fluorescent states, as well as the contribution of specific intermolecular interactions to the total interaction with the medium, is estimated. The role played by the trans-cis isomerization of isolated merocyanine molecules in the deactivation of their excited states is considered.     

阴阳离子菁染料在溴碘化银乳剂颗粒上J-聚体反射光谱

本文对两种阴阳离子菁染料在碘溴化银立方体颗粒表面的聚集行为进行了研究。用紫外-可见分光光度计测定了菁染料J-聚集的反射光谱曲线。与对应的阴离子、阳离子菁染料各自在碘溴化银立方体颗粒表面的聚集进行了实验对比。结果表明:阴阳离子菁染料吸附在碘溴化银立方体颗料表面形成的J-聚集态的反射光谱具有单个阴离子、阳离子菁染料形成J-聚体反射光谱的峰值波长。表明阴阳离子菁染料具有两个感色区域,既有阴离子菁染料的感色区又有阳离子菁染料的感色区。     

Laser properties of fluorescent brightening agents

The laser properties of 19 dyes commonly used as fluorescent brightening agents (FBA) have been studied. A nitrogen laser served as the pumping source. The absorption spectra and the relationship between laser power and wavelength was determined for these dyes. Since several of these compounds have an efficiency comparable to that of the POPOP scintillator commonly used in this part of the spectrum, and since they are easily soluble in alcohols and furthermore, are very inexpensive, they may be competitive with other dyes hitherto used in the violet-blue region.     

混合菁染料J-聚集体的光谱性能研究

对2种混合菁染料吸附在溴化银颗粒表面形成的J-聚集体的反射光谱及感光性能与对应菁染料单独吸附在溴化银颗粒表面进行了对比研究。用紫外-可见分光光计测定了菁染料吸附在溴化银颗粒表面形成J-聚集体的反射光谱。结果表明:2种混合菁染料吸附在溴化银颗粒表面形成的J-聚集体的反射光谱分别具有2个最大峰值波长,并且与对应菁染料单独使用时的峰值波长相一致。2种混和菁染料的感光性能比对应菁染料单独使用时有较大提高。     

食用天然辣椒红色素中掺杂苏丹红的红外光谱快速识别

如何快速检测天然色素中是否掺杂合成色素或者工业染料是食品分析检测中的一个难题。天然辣椒红色素因兼具着色和药理功效而被广泛用于食品中,但又因其稳定性较差而被不法商贩掺杂苏丹红来获利。本文利用红外光谱技术的宏观指纹特性,对掺杂于天然辣椒红色素中苏丹红的1 621,1 500和751cm-1处的强峰,再通过二阶导数图谱分析将谱图信息放大,辅以指纹区684和496cm-1处的谱峰的佐证,可以快速识别辣椒红中是否添加有苏丹红,检测限量可以达到1%。     

分子轨道法计算三苯二恶嗪类分子的电子光谱

采用改进的半经验分子轨道法 (PPP SCF MO)计算了 15种三苯二恶嗪类染料分子的电子结构和电子光谱 ,计算得到的最大吸收峰波长与实验值较好的一致 ,计算得到的荧光跃迁能 ΔEfl 与荧光峰波数νfl 存在如下关系 :νfl =11 6 837ΔEfl+3 34 85 (k·cm- 1 ) ,r=0 95 47,并讨论了电子结构与光谱性能的关系。     

Mutual modification of silver-nanoparticle plasmon resonances and the absorptive properties of polymethine-dye molecular layers on a sapphire surface

Extinction spectra of a hybrid material comprised of molecular layers of polymethine dyes and granulated silver films preliminarily deposited onto sapphire substrates are studied experimentally. Specific features of the dye layer composition and broadening of plasmon absorption bands are discussed. In hybrid samples, both an increase and a decrease in the silver-nanoparticle plasmon resonance frequency upon spreading of dyes have been observed, as well as a considerable increase in the dye molecule absorption. Possible mechanisms of the phenomena are discussed.