Synthesis and spectroscopic characterization of coumarin 440 dye doped silica gel rods

We have studied silica gel by sol–gel technique for the preparation of new dye-laser materials. Silica gel rods with dimension 50 × 10 mm² have been prepared successfully without breaking. It shows high transparency and good mechanical strength. Tetraethylorthosilicate (TEOS), formamide in molar ratio (0.25:0.70), 80 ml ethanol, 20 ml dimethylformamide (DMF), 10 ml water, hydrochloric acid as a catalyst (at pH 6), and 0.5 ml silicone defoaming agent/surfactant have been used. The synthesis has been carried out in a beaker and the reaction mixture is caste in to the flat bottom glass tubes at 40 °C after thoroughly mixing of all the ingredients. These complex reactions, that carried out by hydrolysis and condensation in the silica gel formation show less gel time ∼8–10 h at 40 °C. Coumarin. 440 dye was doped during the preparation of all the ingredients solution mixture. It has been observed that that the compatibility of Nile blue dyes with silica-gel promise good homogeneity with transparency.     

若丹明6G共振增强苯(C6H6)的受激拉曼散射实验研究

报道了若丹明6G乙醇溶液中苯的受激拉曼散射Stokes波共振放大的实验研究.在特定的染料溶液浓度下,1阶、2阶Stokes波得到有效放大,放大倍数分别为3.81和6.1.对荧光共振放大SRS的物理机制进行了分析讨论.     

Enhanced photoluminescence properties of methylene blue dye encapsulated in nanosized hydroxyapatite/silica particles with core-shell structure

Time-resolved interferometric microscopy was applied to investigate laser-induced blistering of a titanium film on a silica substrate. Ablation of the titanium/silica interface by single 0.7 ns pulses within a certain fluence range results in local exfoliation of the metal film from the substrate avoiding, however, complete film destruction. Time-dependent transformation of the metal surface profile was reconstructed from the interference patterns within 0–13 ns time delay range. Transverse annular waves with typical amplitude of one hundred of nanometers and estimated traveling speed of few kilometers per second were revealed on the blister surface. The wave occurrence was attributed to fast inhomogeneous bending of the film covering the expanding blister. The resultant high-frequency (～1 GHz) vibrations of the metal surface provide intensive inertial forces when such metalized target is used for blister-based laser-induced forward transfer of nanopowders and organic molecules.     

Fluorescence properties of riboflavin-functionalized mesoporous silica SBA-15 and riboflavin solutions in presence of different metal and organic cations

Riboflavin was covalently linked to mesoporous SBA-15 silica surface via grafting technique. Then fluorescence properties of the system obtained were analyzed in the presence of several metal and organic cations. Both quenching and strengthening of fluorescence as well as significant changes in the maximum fluorescence wavelength were observed. The results were compared with absorption and fluorescence data obtained for riboflavin water solutions.     

Development of temporal spectroscopic properties for Xerogel matrices doped with Rhodamine 6G dye

The solid host of a laser dye modifies its spectroscopic properties with respect to its liquid host. During the Sol-Gel process the dye molecules suffer from changing their environment. Two parameters affect this matter, the change in the concentration due to the evaporation of the solvent (drying) and the caging of dye molecules inside the pores or attachment to the silica network. Rhodamine 6G absorption and fluorescence spectra with different concentrations, during Sol-Gel time processing, have been studied. Both, absorption and fluorescence spectra of the dye in the solid host, for different concentrations, show a blue-shift relative to its liquid phase.     

High-precision sample stage for photoemission microscopy of organic films

A high-precision sample stage for photoemission microscopy has been constructed to translate the sample by ±3 mm with accuracy better than 100 nm. The stage is actuated by step motors settled outside the vacuum. The accuracies of the translations were measured by observing a standard patterned sample with a photoemission electron microscope (PEEM) of 50 nm resolution. The accuracy was nearly independent of the distance of each translation step and the error was not accumulated by repeated steps. After round-trip translations up to 0.2 mm, the sample came back to the original position with accuracy of ±50 nm. The performance of the stage was demonstrated by observing growth processes of lead phthalocyanine (PbPc) films formed on graphite.     

Tuning the optical properties of Fe-Au core-shell nanoparticles with spherical and spheroidal nanostructures

Present research interest is to highlight on the manufacturing of core-shell nanoparticles because of core activity with unique properties and surface modification by a shell in the diverse fields (e.g. optoelectronic, catalysis and magneto-optics). In addition, the combined optical properties of magnetic-plasmonic core-shell NPs make them ideal candidates for many applications in biomedical fields. The influence of Fe-core and Au-shell for the formation of the core-shell viz. spherical and spheroidal nanostructures is studied using the discrete dipole approximation method. DDA is an approximation method and its accuracy is compared to Mie theory results for spherical core-shell NPs as Mie theory gives the exact solution to spherical targeted NPs. DDA calculations are further extended to spheroidal core-shell nanostructures. It is observed that the localized surface plasmon resonance (LSPR) peak position in considered core-shell nanostructures is enhanced by changing the cores and shell thickness in the core-shell spherical nanostructures and aspect ratio as well as shell thickness in spheroidal core-shell nanostructures. The absorption spectra are found between 363–788 nm wavelength ranges and can be tuned into UV-visible-near-infrared region of the electromagnetic (EM) spectrum in accordance with desired applications. It has been found that the Fe@hollow@Au and prolate core-shell nanostructures show enhancement to LSPR peaks, bandwidth and their corresponding intensities in comparison to other considered spherical and spheroidal core-shell nanostructures. Tunability in core size, shell thickness, aspect ratio, and configuration will open new potential uses of suitable magnetic-plasmonic core-shell nanostructures in cancer therapy, tissue engineering, drug delivery, and many more of biomedical fields.     

Operational characteristics of a dye Q-switch for a pulsed ruby laser

This paper presents the results and analysis of experiments carried out on a dye Q-switch to evaluate its operational characteristics. The work was performed on a ruby laser, Q-switched by cryptocyanine in methanol solution. Investigations of performance with regards to pump energy, dye absorbance, output energy and timing of pulse emergence are graphically presented. These results were used to derive the efficiency of Q-switching for varying dye absorbance. Finally, optimization of the Q-switch performance for different requirements of the laser is considered.     

Detailed analysis of ultrathin fluorescent red dye interlayer for organic photovoltaic cells

The influence of an ultrathin 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) fluorescent dye layer at donor/acceptor heterojunction on the performance of small-molecule organic photovoltaic (OPV) cell is studied. The structure of OPV cell is of indium-tin oxide (ITO)/copper phthalocyanine (CuPc)/DCJTB/fullerene (C₆₀)/bathophenanthroline (Bphen)/Ag. The results show that open circuit voltage (V_OC) increases to 0.57 V as the film thickness of DCJTB layer increases from 0.2 to 2.0 nm. By using an equivalent circuit model, the enhancement of V_OC is found to be attributed to the reduced reverse saturation current density (J_S) which is due to the lower highest occupied molecular orbital (HOMO) level in DCJTB than that in CuPc. Also, the short circuit current density (J_SC) is affected when the DCJTB layer becomes thicker, resulting from the high series resistance R_SA due to the low charge carrier mobility of fluorescent red dye.     

胶束中的若丹明6G荧光增强和激光行为

使用阴离子表面活性剂十二烷基硫酸钠 (SDS)有效的增强了若丹明 6G染料水溶液的荧光 ,在若丹明 6G浓度分别为 5 47× 10 -7和 5 47× 10 -4 mol·L-1时 ,最大增强比率分别为 1 95和 9 7。在后一浓度下SDS的加入使若丹明 6G染料激光阈值降低 ,能量转化效率提高。不加SDS时的激光阈值功率密度约为 6 5MW·cm-2 ,加入 4 1× 10 -2 mol·L-1的SDS后 ,激光阈值功率密度降为 0 8MW·cm-2 。泵浦光功率密度为 6 5MW·cm-2 时 ,能量转化效率达到 2 5 %。同时还观察到SDS的加入使溶液吸收谱、荧光谱和染料激光发生了红移。对以上现象的物理机制进行了讨论。     

Synthesis and spectroscopic characterization of Nile Blue doped silica gel rods

We have studied silica-gel by sol–gel technique for the preparation of new dye-laser materials. Silica gel rods with dimension 50 mm × 10 mm have been prepared successfully without breaking. It shows high transparency and good mechanical strength. Tetraethylorthosilicate (TEOS), formamide in molar ratio (0.25:0.70), 80 ml ethanol, 20 ml dimethylformamide (DMF), 10 ml water, hydrochloric acid as a catalyst (at pH 6) and 0.5 ml silicone defoaming agent/surfactant have been used. The synthesis has been carried out in a beaker and the reaction mixture is caste in to the flat bottom glass tubes at 40 °C after thoroughly mixing of all the ingredients. These complex reactions, that carried out by hydrolysis and condensation in the silica gel formation show less gel time ∼8–10 h at 40 °C. The doping of dye (Nile Blue 690) has been taken during the preparation of all the ingredients solution mixture. It has been observed that the compatibility of Nile Blue dye with silica-gel promise good homogeneity with transparency.     

基于红色荧光染料3-(dicyanomethylene)-5, 5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene的高性能白色有机电致发光器件

研究了基于红色荧光染料3-（dicyanomethylene）-5, 5-dimethyl-1-（4-dimethylamino-styryl） cyclohexene（DCDDC）的白色有机电致发光器件的性能,分别制备了基于DCDDC超薄层和DCDDC掺杂主体材料的两种器件结构: 1）indium-tin oxide（ITO）/N, N′-diphenyl-N, N′-bis（1-naphthyl-pheny1）-1, 1′-biphenyl-4, 关键词： 有机电致发光器件 白色发光 红色荧光染料 掺杂     

Analysis of interaction between the organic dye methylene blue and the surface of AgCl(I) microcrystals

We have used IR spectroscopy to study the nature of interaction between molecules of the organic dye methylene blue (MB) and the surface of AgCl(I) microcrystals. We recorded the IR absorption spectra of the organic dye methylene blue in the gas phase, adsorbed on the surface of AgCl(I) microcrystals, and also in the form of crystal hydrates. The results obtained allowed us to hypothesize that unsaturated dimethylamino groups and the sulfur atom in the heterocycle of this dye are the most active in the interaction between methylene blue molecules and the surface of AgCl(I) microcrystals. With the help of IR spectra of methylene blue crystal hydrates, we confirmed the significant role of OH groups during adsorption of molecules on the surface of AgCl(I) microcrystals. We suggest the possibility of formation of hydrogen bonds between the anions of the crystal lattice and the unsaturated dimethylamino groups as well as the sulfur atoms in the heterocycle, by formation of hydrogen bonds with the OH groups. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 731–737, November–December, 2007.     

Continuous wave stimulated Raman scattering of benzene by fluorescence enhancement in hollow fused silica fiber

We present continuous wave stimulated Raman scattering (SRS) of benzene (C₆H₆) influenced by the fluorescent dye m‐cresol purple in a hollow fused silica fiber (HFSF). Because of the transmission loss of the HFSF filled with C₆H₆, the SRS occurs when the Stokes gain equals the transmission loss, with the loss taken at the Stokes wavelength. The 992 cm⁻¹ stimulated Stokes line has been obtained at the pump wavelength 658 nm, which cannot be obtained at 532 nm because the Stokes wavelength (562 nm) does not locate in the transmission loss. Also, the pump power is 35 mW with m‐cresol purple which is much lower than 800 mW without the dye. The profile of the 992 cm⁻¹ stimulated Stokes is changed, and the weak shoulders of the profile are amplified by fluorescence. These results are expected to be of relevance in applications on the tunable Raman laser at new wavelengths. Copyright © 2011 John Wiley & Sons, Ltd.     

Au@SiO2 core/shell nanoparticle assemblage used for highly sensitive SERS‐based determination of glucose and uric acid

The use of Au@SiO₂ core/shell nanoparticle (NP) assemblage with highly sensitive surface‐enhanced Raman scattering (SERS) was investigated for the determination of glucose and uric acid in this study. Rhodamine 6G dye molecules were used to evaluate the SERS enhancement factor for the synthesized Au@SiO₂ core/shell NPs with various silica shell thicknesses. The enhancement of SERS signal from Rhodamine 6G was found to increase with a decrease in the shell thickness. The core/shell assemblage with silica layer of 1–2 nm over a Au NP of ~36 nm showed the highest SERS signal. Our results show that the SERS technique is able to detect glucose and uric acid within wide concentration ranges, i.e. 20 ng/dL to 20 mg/dL (10⁻¹²–10⁻³ M) and 16.8 ng/dL to 2.9 mg/dL (10⁻¹¹–1.72 × 10⁻⁴ M), respectively, with associated lower detection limits of ~20 ng/dL (~1.0 × 10⁻¹² M) and ~16.8 ng/dL (~1.0 × 10⁻¹¹ M). Our work offers a low‐cost route to the fabrication of agile sensing devices applicable to the monitoring of disease progression. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis, characterization of ceria-coated silica particles and their chemical mechanical polishing performance on glass substrate

Nano-sized ceria particles were coated on the silica surface by the precipitation method using ammonium cerium nitrate and urea as precipitant with poly(vinylpyrrolidone) (PVP) as assistant. The structures and compositions of ceria-coated silica particles were characterized using X-ray diffraction (XRD), field-emission scanning microscopy (FE-SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The results show that nano-size ceria particles were coated uniformly around the surface of silica particles when PVP was used as assistant during coating process, while without PVP, the ceria particles were grown sparsely on the silica particle surface and many ceria particles grow up through independent nucleation in the solution. Then, the chemical mechanical polishing (CMP) behaviors of the as-prepared ceria-coated silica particles on glass substrate were investigated. The CMP test results suggest that the as-prepared ceria-coated silica particles exhibit higher removal rate than pure silica particles without deteriorating the surface quality. In addition, online coefficient of friction (COF) was conducted during the polishing process. The COF data indicate that the COF values of ceria-coated silica particles are larger than those of pure silica particles due to their surface properties.     

Synthesis and characterization of Mn-doped Zn2SiO4/SiO2 phosphor particles in core-shell structure

Manganese-doped zinc silicate (Zn₂SiO₄:Mn) is a kind of phosphor material that has a photo-luminescent (PL) and cathode-luminescent (CL) properties with intensive green light emission at 520 nm. The particles consisting of SiO₂@Zn₂SiO₄:Mn (SiO₂ core-Zn₂SiO₄:Mn shell) were synthesized via colloidal process and forced precipitation. After drying, the Zn/Mn precipitates were coated on the surface of SiO₂ particles. The Zn/Mn precipitates reacted with SiO₂ and transformed to Zn₂SiO₄:Mn by suitable calcination. The microstructure, crystalline phase, and luminescent characteristics of the products were studied. Besides, a CL device consisting of the core-shell powder was characterized.     

Study on triplet exciton diffusion length of mCP in phosphorescent organic light-emitting devices using electroluminescent spectra

Electroluminescent (EL) spectra was employed to probe the triplet exciton diffusion length (L_T) of a commonly used host material of N,N′-dicarbazolyl-3,5-benzene (mCP) in phosphorescent organic light-emitting devices (OLEDs). By varying the film thickness of bis [2-(4-tertbutylphenyl) benzothiazolato-N,C²], iridium (acetylacetonate) [(t-bt)₂Ir(acac)] phosphor doped layer within 30 nm thick mCP layer, a series of devices were fabricated to investigate the EL characteristics. The results showed that with the increasing doped layer thickness (d), both (t-bt)₂Ir(acac) emission peaks at 562 nm and mCP emission centered at 403 nm were observed. Moreover, the relationship between mCP EL intensity and d was detected. The L_T was induced by an abrupt decrease in variation of mCP EL intensity when d is increased from 10 to 15 nm, and the reason to cause this phenomenon was investigated. The L_T of mCP approximately to 15 nm was perfectly consistent to the result of 16±1 nm, which was calculated by the traditional steady-state diffusion model.     

Phase defect inspection of multilayer masks for 13.5 nm optical lithography using PEEM in a standing wave mode

We report on recent developments of an “at wavelength” full-field imaging technique for defect inspection of multilayer mask blanks for extreme ultraviolet lithography (EUVL). Our approach uses photoemission electron microscopy (PEEM) in a near normal incidence mode at 13.5 nm wavelength to image the photoemission induced by the EUV wave field on the multilayer blank surface. We analyze buried defects on Mo/Si multilayer samples down to a lateral size of 50 nm and report on first results obtained from a six inches mask blank prototype as prerequisite for industrial usage.     

Studies of the optogalvanic effect in a commercial caesium hollow cathode lamp and its use for tuning pulsed dye lasers

The use of the optogalvanic effect (OGE) in a hollow cathode lamp for wavelength tuning of dye lasers is an established technique at laser wavelengths longer than 560 nm, corresponding to photon energies less than 2.2 eV. This work describes the first successful optogalvanic studies on caesium at higher photon energies. Once set up, OGE in a standard commercial hollow cathode lamp provides a quick and cheap means of tuning a continuously tunable laser to a chosen atomic transition. The lines in caesium at 455.55 nm and 459.32 nm were resolved. This work is also believed to be the first to describe the detection of any caesium transition using the optogalvanic effect in a commercial hollow cathode lamp, rather than a specially constructed tube. The method used is applicable to other materials which have previously proved difficult.