Comparative photophysical and energy transfer studies of C480:C535 binary dye mixture in solid and liquid environments

The spectral behaviour of the individual dyes (C480 and C535) is discussed. The absorption and fluorescence spectral profiles of the dyes, in solid and liquid environments, are identical. Dye doped polymer rods of donor dye (C480) without the acceptor dye (C535), acceptor dye (C535) without the donor dye (C480) and donor dye with acceptor dye at different acceptor concentrations are synthesized. Energy transfer technique is studied, in detail, using these rods. The results obtained are compared with their respective liquid mixtures. Optical gain of the acceptor dye with and without the donor dye is determined experimentally, in both solid and liquid media. The gain of the acceptor with donor increases and then decreases with increase in acceptor concentration. Both solid and liquid media show similar trends. But, the gain coefficient in the solid matrix is less than that in the liquid medium. The photobleaching of the dye doped polymer rod under nitrogen laser excitation is studied.     

Gain studies of Coumarin 503 dye-doped polymer laser

Solid-state dye doped polymer is an attractive alternative to the conventional liquid dye solution. In this paper, the laser characteristics of Coumarin 503 (C503) doped polymethyl methacrylate (PMMA) rods modified with ethyl alcohol (EtOH) are studied under nitrogen laser excitation in a transverse pumping configuration and the variation of gain of the dye in solid medium for different pumping powers is studied. The gain of Coumarin 503 in solid medium is compared with the gain of Coumarin 503 in liquid medium and it is found that the gain of the dyes in the solid environment is less than that in the liquid environment. The photobleaching of dye in polymer medium under nitrogen laser excitation is also studied by keeping the rod in a fixed position and by rotating the rod about its cylindrical axis. It is found that the photobleaching rate is faster when the rod is in a fixed position.     

Energy transfer in solid-state dye lasers based on methyl methacrylate co-doped with sulforhodamine B and crystal violet

Laser action in methyl methacrylate(MMA)co-doped with sulforhodamine B and crystal violet dyes was investigated.The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd:YAG laser.Distributed feedback dye laser(DFDL)action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism.Theoretically,the characteristics of acceptor and donor DFDLs,and the dependence of their pulse widths and output powers on acceptor–donor concentrations and pump power,were studied.Experimentally,the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor–donor concentrations.Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium.The laser wavelength showed continuous tunability from 563 nm to648 nm.     

Gain studies of coumarin 307 dye doped polymer laser

Solid state dye doped polymer is an attractive alternative to the conventional liquid dye solution. In this paper the laser characteristics of coumarin 307 (C307) doped polymethyl methacrylate rods modified with dioxane are studied under nitrogen laser excitation in a transverse pumping configuration and the variation of gain of the dye in solid medium for different pumping powers is studied. The photobleaching of dye doped polymer rod is also studied.     

Experimental investigations on energy-transfer characteristics and performance of some laser dye mixtures

Energy transfer from both Coumarin 120 (C120) and p-Bis(o-methylstyryl)-benzene (Bis-MSB), energy donors, to coumarin 7(C7) (acceptor) individually has been studied by steady-state emission measurements in methanol. The dye laser characteristics of the above-mentioned dyes have also been studied with respect to the energy transfer mechanism in the same solvent using a pulsed nitrogen laser as a pumping source. The large values of the critical transfer distances, R₀, indicate that the dominant mechanism responsible for energy transfer is due to long-range dipole–dipole interaction between the excited donor and ground state acceptor molecule. Both photophysical and photochemical stability of the donors has been examined under the effect of N₂ laser pumping.     

Mechanisms of Fluorescence Quenching in Donor—Acceptor Labeled Antibody—Antigen Conjugates

The cyanine dyes Cy5 and Cy5.5 are presented as a new long wavelength-excitable donor-acceptor dye pair for homogeneous fluoroimmunoassays. The deactivation pathways responsible for the quenching of the fluorescence of the antibody-bound donor are elucidated. Upon binding of the donor dye to the antibodies at low dye/protein ratios, its fluorescence quantum yield rises to unity. Higher dye/protein ratios lead to progressive aggregation of the dyes, which results in quenching of monomer fluorescence due to resonance energy transfer (RET) from the monomers to the nonfluorescent dimers. The dependence of the quenching efficiency on the labeling ratio is described quantitatively by assuming a Poisson distribution of the dyes over the antibodies. The maximum fluorescence intensity per antibody is obtained at a labeling ratio of 4. Upon formation of the antibody-antigen complex, electron transfer and RET to the antigen-bound acceptor dye occur. Steady-state and time-resolved fluorescence measurements reveal that approximately 50% of the donor quenching is due to RET, while the residual quenching effect is caused by the static quenching process.     

Fluorescence and Laser Emission from Coumarin-Acridine Orange Mixtures

The sensitized fluorescence and laser emissions of dye mixtures; (I) coumarin 102 (donor) and acridine orange (acceptor) and (II) coumarin 47 (donor) and acridine orange (acceptor) with Hg-lamp and N₂ laser, have been measured as a function of dye concentration and of the pump power (N₂ laser). Acridine orange which does not lase by itself on excitation with N₂ laser, lases efficiently in the presence of 7-amino-coumarins via singlet-singlet energy transfer. Energy transfer rate constants and critical distances have been estimated from fluorescence intensity and lifetime measurements. The performance of energy transfer dye lasers (ETDLs) are discussed in terms of spectral characteristics of the dyes and their penetration depths.     

Photo-physical properties and quantum yield of some laser dyes in new polymer host

The field of laser dyes-active solid polymer materials is a promising field and quite competitive with liquid dye lasers. This paper investigates some photo-physical parameters of pyromethene (PM-567, PM-597) and Rhodamine B dyes incorporated into glycidyl methacrylate (GMA) promising polymeric host matrix. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to FT-Raman spectra as an indication for binding the dye molecules with the backbones of GMA polymeric chain.     

Tunable energy transfer distributed feedback dye laser using pyronin B and crystal violet dye mixture

Using pyronin B and crystal violet dye mixture, the characteristics of energy transfer distributed feedback dye laser (ETDFDL) pumped by 532 nm Nd:YAG laser were investigated. The characteristics of donor DFDL and acceptor DFDL as well as the dependence of their pulse widths and output powers on pump power and acceptor concentrations were studied. The output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and acceptor concentrations, and tunability was observed from 570 to 645 nm using prism dye cell arrangement.     

Laser emission from mixtures of dipyrromethene dyes in liquid solution and in solid polymeric matrices

Laser emission from binary mixtures of different dyes both in liquid solution and incorporated into solid polymeric matrices, covering the spectral region from green to red, is investigated. Mixtures of two synthesized dyes, analogs of the commercial dye Pyrromethene 567 (PM567), allowed covering the spectral range from green to orange. Tuning ranges in solid state of up to 42 nm with good photostabilities were demonstrated. To extend the tuning range to the red, binary mixtures of the dyes Pyrromethene 597 (PM597)/Pyrromethene 650 (PM650), PM567/DCM, and PM597/DCM were also studied. In liquid solution, a mixture of dyes PM567 and DCM allowed for narrow-linewidth laser emission continuously tunable over a range of 85 nm. In solid-state, mixtures of dyes PM597 and PM650 allowed laser emission tunable over two separate spectral regions up to a wavelength of 619 nm.     

Time-resolved fluorescence of cationic dyes covalently bound to poly(methacrylic acid) in rigid media

Atactic poly(methacrylic acid) labeled with acridine and Nile blue (NB) were studied by photophysical techniques in bulk solid state and in solution-cast films over different surfaces (glass, ITO, and polymethylmethacrylate). In the systems with both dyes, energy transfer from acridine to NB occurs with an efficiency depending on the type of substrate (solid or film). The films are more disordered fluorescent rigid media than the bulk chromophoric or bichromophoric polymers, and this effect is ascribed to inhomogeneous distribution of the dyes in the film. This effect enhances dye bimolecular interactions and increases the energy transfer rates between acridine donor and NB acceptor. Bimodal distributions of donor fluorescence lifetimes are observed.     

沢吨染料的光化漂白动力学及全息特性研究

研究了以三乙醇胺作为引发剂,五种沢吨染料的光化漂白过程.实验结果表明五种染料的光化漂白速率大小顺序是藻红B(ErB)＞曙红Y(EY)＞孟加拉玫瑰红B(RsB)＞罗丹明B(RoB)＞荧光素(F).并研究了曝光强度及染料浓度对漂白过程的影响,以及这五种染料的全息记录性能.     

Tunable picosecond energy transfer distributed feedback dye laser using Rhodamine 6G and Thionine dye mixture

The characteristics of Nd:YAG laser pumped energy transfer distributed feedback dye laser (ETDFDL) is studied both theoretically and experimentally. Using theoretical model proposed the behaviour of ETDFDL for dye mixture Rhodamine 6G and Thionine is studied in detail. The characteristics of donor DFDL, the acceptor DFDL, the dependence of their pulse widths and output powers on donor–acceptor concentration and pump power are studied. The output energy of DFDL is measured experimentally at the emission peaks of donor and acceptor dyes for different pump powers and donor–acceptor concentrations. In addition, the tunability of DFDL emission is measured both in donor and acceptor emission ranges.     

Photophysics of two structurally similar dyes containing substituted amino as donor and carbonyl as acceptor groups

The present work entails a comparative photophysical study of two structurally similar donor–acceptor dyes. In one of the dyes (DN2) twisting about C–N bond is permissible, while twisting is strategically restricted in the other (N2). Optical responses of both the dyes have been monitored in pure and mixed binary solvents comprising of mainly aprotic+protic systems. Results indicate that the nature of emitting states in protic and aprotic microenvironments is different for the two dyes. In aprotic media the solvated dye molecule is the emitting species while emission mainly takes place, supposedly, from the dye-solvent hydrogen bonded complex in protic media. The parallel behaviour of the two dyes indicates that twisting about C–N bond in the excited state is not an important photophysical process. Further, the effect of addition of strong acid to the dye solution and the corresponding existence of equilibrium between two tautomeric forms for both the dye has been studied.     

Spectroscopic and lasing properties of Xanthene dyes encapsulated in silica and polymeric matrices

The photo-physical properties of Xanthene dyes: Basic Rhodamine Yellow (BRY), Rhodamine590perchlorate (R590p), SulforhodamineB (SRB) doped in tetramethylorthosilicate (TMOS) and poly-methylmethacrylate (PMMA) are observed. The various parameters viz. full-width at half-maxima (FWHM), peak emission wavelength, quantum yield and excited state lifetime at different concentrations ranging from ∼0.05 to ∼1 mM of the dye under excitation by Copper Vapor Laser (CVL) of high repetition rate (∼5.6 kHz) of are investigated. In order to identify photostability in dyes, normalized photostability has been studied and found that silica gel samples containing dye are more stable than that of polymeric samples. This has been further understood in terms of number density of unbleached dye molecules that infers that photobleaching of dye molecules is not prominent at higher concentrations in glassy solid matrices. Pump intensity dependent optical gain of the samples has also been reported and efforts have been made to study the efficiency of solid-state laser samples in a cavity for the performance of the dye laser.     

Fabrication of Semiconductor Polymer Membranes Combined with a Colored Charge Transfer Complexes Used in the Manufacture of Solar Cells as a Source of Alternative Energy

The main task of this article was to prepared of new pigment model in situ solar cells accordance to charge-transfer complexes of rhodamine C (RhC) donor as dye laser gain media with iodine (σ-acceptor) and chloranilic acid, CLA (π-acceptor). The synthesis stoichiometry of these complexes were of 1∶2 (donor∶acceptor) with general formulas [(RhC)]I·I₃ and [(RhC)(CLA)₂]. The discussed data of elemental analysis, conductivity measurements, FT-IR, UV-Vis spectroscopy and photometric titration data visualized the stoichiometry, formula and complexity of the complexes. The physicochemical and spectroscopic analyses obtained suggested that the electron transfer occurred through nitrogen atom in a tertiary amine -N(C₂H₅)₂ of RhC donor with acceptor. The synthesized solid complexes were under go to thermogravimetric analyses to investigate their thermal stability and decomposition steps. The molar conductance measurements revealed that RhC complexes have an electrolytic statement. The thermal stability of rhodamine C complexes was enhanced in comparable with RhC itself. The polymer membranes of poly-methyl methacrylate) (PMMA) combined with the RhC charge(transfer complexes in chloroform solvent have been prepared and characterized by (infrared & electronic) spectroscopy and scanning electron microscopy (SEM) morphological examination. The photo-stability properties of the RhC complexes have been investigated.     

Highly photostable laser solution and solid-state media based on mixed pyrromethene and coumarin

A substantial increase in the photostability of pyrromethene 567 laser dye solutions and in solid polymer media has been achieved by the addition of coumarin C540 laser dye. Up to five times increase in photostability of pyrromethene 567 in solid and two times in solution has been observed. The enhanced photostability is attributed to reduction in the effectiveness of in situ oxygen degradation of pyrromethene by the addition of the coumarin.     

Dynamics of fluorescence of solid solutions of quantum dots and the organic dye DODCI: Experiment and numerical simulation

The fluorescence of solid solutions of CdSe/ZnS quantum dots and the organic dye DODCI is investigated. It is shown that nonradiative transfer of electronic excitation energy to dye molecules, which with some probability lose their acceptor properties as a result of photoisomerization or photodegradation, is responsible for a significant increase in the fluorescence intensity of a donor. The degree of polarization of the donor fluorescence attains values exceeding 0.5, which is due to the difference in the fluorescence quantum yields of donors with different orientations of the oscillator with respect to the electric vector of an excitation light wave. A numerical simulation of the experimentally observed dependences is performed.     

Fluorescent polystyrene microspheres with large Stokes shift by fluorescence resonance energy transfer

We prepared fluorescent microspheres with notably large Stokes shift and long-wavelength fluorescence by applying fluorescence resonance energy transfer (FRET) between two common julolidine dyes. Short distance between dye molecules caused by high dye concentration results in efficient FRET in microspheres. However, adequate dye concentration and moderate molar ratio of the donor and acceptor should be chosen to avoid aggregation of dye molecules, which leads to the decrease of fluorescent intensity. Microrspheres with average distance between dye molecules of 1.94 nm and molar ratio of 3.08:1 realize highly efficient FRET with no fluorescence of donor and intense long-wavelength emission of acceptor. In addition, the applied solvent evaporation method for preparing microspheres provided better protection of dyes from ambient medium than traditional surface-labeled method. These results demonstrate the feasibility of applying FRET in microspheres to expand useful fluorescent probes, and reveal their potential application in bioassays field.