DCM Dye Research Articles

Гибридные сферические микрорезонаторы с люминесцентными органическими красителями FITC и DCM

Luminescent hybrid spherical microresonators of two types consisting of monodisperse spherical silica particles with a diameter of 3.5 mcm coated with either FITC dye molecules or a 200 nm thick mesoporous silica shell containing DCM dye are fabricated. The luminescence spectra of microresonators are studied and the experimental emission spectra are simulated using the method of spherical wave transfer matrices. The ratio of intensities of emission lines into whispering gallery modes with different polarizations and the same polar and radial indices is analyzed. It is shown that the ratio depends on the orientation of the dipole moment of the radiative transition of dye molecules relative to the surface of spherical silica particles.

Hybrid spherical microresonators with luminescent organic dyes FITC and DCM

Luminescent hybrid spherical microresonators of two types consisting of monodisperse spherical silica particles with a diameter of 3.5 μm coated with either FITC dye molecules or a 200 nm thick mesoporous silica shell containing DCM dye are fabricated. The luminescence spectra of microresonators are studied and the experimental emission spectra are simulated using the method of spherical wave transfer matrices. The ratio of intensities of emission lines into whispering gallery modes with different polarizations and the same polar and radial indices is analyzed. It is shown that the ratio depends on the orientation of the dipole moment of the radiative transition of dye molecules relative to the surface of spherical silica particles. Keywords: spherical microresonator, whispering gallery modes, organic dyes, photoluminescence.

Optically guided spatially modulated Laser generation with DCM dye-doped in the liquid crystal layer

The article proposes laser-active layers that generate and reconstruct optical information through their own laser radiation. At this time, the excitation of the laser layer (optical pumping) is carried out holographically, the interference of two mutually coherent waves through the image. The II (532 nm) and III (355 nm) harmonics of the coherent emission of the Nd: YAG laser was used for holographic optical pumping of the laser layers, based on which the characteristics of the laser radiation of liquid crystal structures doped with DCM dye were studied.

Low-threshold and narrow-emission random lasing in a self-assembly TiN nanoparticle-doped carbon quantum dot/DCM nanowire composite

The random lasing in quantum dot systems is in anticipation for widespread applications in biomedical therapy and image recognition, especially in random laser devices with high brightness and high monochromaticity. Herein, low-threshold, narrowband emission, and stable random lasing is realized in carbon quantum dot (CQD)/DCM nanowire composite-doped TiN nanoparticles, which are fabricated by the mixture of carbon quantum dots and self-assembly DCM dye molecules. The Förster resonance energy transfer process results in a high luminescence efficiency for the composite of carbon dots and DCM nanowires, allowing significant random lasing actions to emerge in CQD/DCM composite as TiN particles are doped that greatly enhance the emission efficiency through the plasmon resonance and random scattering. Thus, sharp and low-threshold random lasing is finally realized and even strong single-mode lasing occurs under higher pumping energy in the TiN-doped CQD/DCM composite. This work provides a promising way in high monochromaticity random laser applications.

High-Speed Diagnostics For The Study Of Droplet Breakup

In this work, we demonstrate the use of planar laser-induced fluorescence (PLIF) and back-lit shadowgraph imaging at 1.75~MHz to study the breakup of a 1-mm-diameter liquid drop in the presence of an air jet intersecting the drop's velocity vector. For the PLIF, a 447-nm laser diode is focused to form a high-intensity sheet to excite the DCM dye suspended in the ethanol droplet. For the back-lit shadowgraphy, a 685-nm fiber-coupled laser diode is used to generate a collimated beam of light to illuminate a stream of droplets as they are disrupted by a jet of air. All the complications associated with performing experiments in a ballistic range (luminosity filter, single-event triggering, standoff distance, etc.) were taken into account in this laboratory setup.

Influence on the generating losses on the spectral efficiency of ethanol solutions of dyes of various classes

The generation efficiency of a number of ethanol dye solutions is studied as a function of the coherent microsecond pump wavelength. It is shown that the maximum lasing efficiency is achieved by pumping not to the maximum of the main band of the absorption spectrum of dyes. In the spectral ranges determined for each dye, a decrease in the generation efficiency is observed. The reasons for this phenomenon – triplet-triplet and singlet-singlet absorption – are analised. The main role in the case under consideration is played by the absorption of pump radiation in the system of excited singlet levels with the formation of long- and short-lived photoproducts that absorb in the amplification region but do not participate in generation. A study of the luminescence kinetics of the DCM dye showed that another reason for the appearance of induced losses is the non-linear scattering of radiation in a dye solution, which occurs because of non-stationary self-diffraction of pump radiation on phase noise gratings formed as a result of heat release when light is absorbed in the channel of excited singlet levels in a bleaching dye solution. Experiments on probing induced losses, as well as picosecond spectroscopy, confirmed the appearance of thermooptical distortions of the active medium in certain spectral intervals of microsecond coherent pumping.

Low-threshold random lasers enhanced by titanium nitride nanoparticles suspended randomly in gain solutions.

In this article, we report a low-threshold random laser enhanced by TiN nanoparticles (NPs) suspended randomly in gain solutions. Results show that the random laser with TiN NPs has a lower threshold than the random laser with TiO2 NPs and the underlying mechanisms are discussed in detail. The localized surface plasmon resonance of individual TiN NPs increases the pump efficiency and strengthens the fluorescence amplification efficiency of the DCM. The multiple scattering of integral TiN NPs extends the dwelling time of light in random systems, which provides more possibilities for the light amplification in the gain medium. Then, the random laser threshold as a function of the number density of TiN NPs is studied. Results show that the optimum number density of TiN NPs for the lowest-threshold random lasers is about 1.468 × 1012ml-1. When we substitute the ethanol solution with the nematic liquid crystal (NLC), the random laser threshold can be further decreased to 5.11 µJ/pulse, which is about 7.7 times lower than that of DCM dye solution with TiN NPs under the same conditions. These findings provide a cost-effective strategy for the realization of low-threshold random lasers with high-quality.

Spectral and emission characteristics of DCM and oxazine laser dyes in annealed silica xerogel

Spectral and emission characteristics of DCM and oxazine laser dyes in annealed silica xerogel

Comparative studies on biophysical interactions between 4-dicyanomethylene-2,6-dimethyl-4H-pyran (DDP) with bovine serum albumin (BSA) and human serum albumin (HSA) via photophysical approaches and molecular docking techniques

Photophysical studies of 4-Dicyanomethylene-2,6-Dimethyl-4H-Pyran (DDP) dye with globular proteins, Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) were carried out in aqueous solution. An isosbestic point resulted on the addition of serum albumins, which signifies a complex or an equilibrium state of DDP dye with albumin. Addition of BSA to DDP dye results in a fluorescence enhancement accompanied with a significant hypsochromic shift, whereas with that of HSA, a fluorescence quenching with a considerable blue shift resulted. Excited state studies of DDP dye with serum albumins portray that the role of binding sites of dye with albumins vary considerably and the nature of interaction is presumably attributed to combined hydrogen-bonding and hydrophobic interactions. Molecular docking studies of DDP dye with albumins and two other derivatives 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) dye and 4-(Dicyanomethylene)-2-methyl-6-(4-t-buyl)-4H-pyran (DCT) dyes with BSA and HSA elucidates that the hydrogen-bonding interaction accompanied with several hydrophobic, pi–pi an pi–alkyl interactions coexist between dye and albumins. The binding energy, intermolecular energy and stability of the DDP, DCM and DCT dyes through docking techniques with albumins authenticate that the dye predominantly acts as hydrogen-bonding acceptor site and the protein molecule as the donor. DDP dye prefers to exist in four different binding sites of HSA, whereas, in the case of BSA, the most preferred site is found to be hydrophobic domain (site I). Interestingly, the most preferred site of DCT dye is III A subdomain of HSA, whereas DCM dye is oriented towards I B subdomain. DDP and DCT are smaller in size and reside in the domain preferred for smaller ligands (II A and IIIA) as resulted in several drugs-HSA interaction whereas DCM dye which is categorized as medium to larger ligand based on the extended structure resides in the most favoured site IB. Fluorescence techniques in combination with molecular docking methods elucidate binding characteristics and the domain in which the dye resides in a micro heterogeneous environment is established in this study.

Analysis of the (0,0) band of the new [15.3]Ω=3/2 – X2Π3/2 electronic transition of PtF using intracavity laser spectroscopy

A rotational analysis of the electronic transition of PtF occurring at 15,252 cm−1 was recorded and analyzed. This transition is identified as the (0,0) band of the [15.3]Ω=3/2 – X2Π3/2 electronic transition. The PtF molecules were produced in a current regulated RF-pulsed DC discharge operating with 0.80 A applied to a Pt-lined copper hollow cathode in 0.50–1.25 Torr of 1–5% SF6 in an Ar/He sputter gas mixture. The hollow cathode was placed within in the resonator cavity of a tunable DCM dye laser operating over the 14,500–16,500 cm−1 range, and path lengths of 0.2–2.0 km were utilized with the intracavity laser spectroscopy (ILS) method. The data were fit in PGOPHER using a polynomial energy level expression. Molecular constants for the excited state are presented. The nature of the new [15.3]Ω = 3/2 state is discussed.

Low-coherence dye laser with an intracavity radiation diffuser.

Study of a low-coherence dye laser is reported. A cuvette with a 2 mm gap containing a dense mixture (slurry) of LiF crystal granules (70-140 μm) and an immersion liquid with a dye dissolved in it was installed in a double flat mirror cavity as an active element and simultaneously as a diffuser of radiation. The parallel light beam experiences losses in such a cuvette due to refraction at a set of interfaces between solid particles and a liquid in which different parts of the beam are randomly deflected at small angles. Measurements of the loss coefficients, angles of rays' deflection in the cuvette-diffuser were carried out. When this cuvette was pumped by 25 ns pulses of the 2nd harmonic of a Nd:YAG laser, 20 ns pulses of radiation in the region of 550-650 nm with energy ≈1 mJ at a beam divergence 5-80 mrad, and a degree of spatial coherence γ ≲ 0.1 were obtained in slurry with PM567, Rh101 or DCM dyes. The features of spectra and spatial-angular characteristics of these slurry lasers are discussed, tuning of the spatial coherence of radiation is demonstrated. Possible applications of a dye laser with an intracavity diffuser as a source of low-coherence radiation are considered.

Forster resonance energy transfer assisted white light generation and luminescence tuning in a colloidal graphene quantum dot-dye system

The development of white light-emitting LED (WLED) is now one of the important demands of present society due to its energy saving feature. However, in this work, an ingenious strategy has been employed to develop Forster resonance energy transfer (FRET) based and rare-earth material free luminescent duo (LD) for the generation of white light. A colloidal LD, consisting of nitrogen-doped graphene quantum dots (N-GQDs) and DCM dye (DCM@N-GQDs), is employed for demonstrating the FRET. The band-gap is engineered by nitrogen (N) doping in GQDs, and an energy transfer efficiency of ~30% for white light generation is attained. The widely tunable PL emission from blue to the red region has been obtained by changing the D-A ratio. Therefore, the present work has provided an alternate approach to widen the light emission band of a conventional laser dye, which is otherwise restricted within a limited region of the visible spectrum. FRET-based WLED (F-WLEDs) with colour rendering index of 70 and correlated colour temperature of 4690 K have also been fabricated. The F-WLED exhibits an emission overlapping of 56% with the solar spectrum (AM 1.5) in visible region, which is doubled in compared to that of a commercial WLED. The present report of rapid synthesis of highly luminescent N doped GQDs and the strategy used here for generation of FRET based colloidal DCM-GQDs luminescent duo may also be extended further with other suitable laser dyes for further widening as well as tuning the spectral range of light emissions of different commercially available laser dyes and GQDs for their different photonic applications.

Co-amplification: An efficient spectral beam combination approach for high power, closely separated dual wavelength dye laser systems

Characteristics of an efficient spectral beam combination of two dye laser beams with wavelength difference of less than 10 nm are presented. Two dye laser oscillator beams were spatially and temporally combined with reduced losses before their co-amplification in a common power amplifier. Yellow and green beams of 9 kHz (pulse repetition rate) copper vapour laser (CVL) Master Oscillator Power Amplifier (MOPA) Chain were utilised to pump Rh 101 dye laser oscillators and DCM dye common amplifier respectively. The characteristics of green beam pumped DCM dye common amplifier were studied at various pump power and input power ratios. Combination losses for this configuration were 40% relative to individually amplified configuration. Input–output characteristics of the common amplifier were determined at various input power ratios. Composite dual wavelength dye laser beam having total power of 7.35W at 38.4 W pump power with extraction efficiency 16.5% was demonstrated.

Rotational analysis of the [15.1] A″–[formula omitted]1A′ transition of CuOH and CuOD observed at high resolution with Intracavity laser spectroscopy

While mentioned briefly in the analysis of the A∼1A′–X∼1A′ transition of CuOH by Jarman et al. (1991), the 6640 Å band system of CuOH has never been rotationally analyzed. In this work, that band system has been observed and recorded in absorption at high resolution using Intracavity Laser Spectroscopy (ILS), and has been assigned as the v″ = v′ = 0 vibrational band of the [15.1] A″–X∼1A′ transition of CuOH. The CuOH molecules were produced in current-regulated RF discharges formed when 0.40 A was applied to a Cu hollow cathode in ∼500 mTorr of O2 with a trace amount of H2. CuOD molecules were produced in a similar fashion with a discharge current of 0.45 A, and a gas mixture that was ∼80:20% O2:D2. The hollow cathode was located within the resonator cavity of a DCM dye laser that was tuned over the 14,500–16,500 cm−1 range with an optically transparent wedge. Pathlengths of ∼10 km were utilized with the ILS method. The (1,0), (0,1), and (1,2) Ka sub-bands with (Ka′,Ka″) of 63CuOH; the (1,0) and (0,1) Ka sub-bands of 65CuOH; and the (2,1), (1,0), (0,1), (1,2) and (2,3) Ka sub-bands of 63CuOD were included in the rotational analysis. The transitions were fit to a Watson S-reduced Hamiltonian using PGOPHER, and the pure rotational transitions for 63CuOH, 65CuOH, and 63CuOD [J. Chem. Phys., 112, 641 (2000)] were included in the fit. The molecular constants determined by the fit were used to calculate an r0 structure for the [15.1] A″ state. A global perturbation was observed for J′ > 20 in Ka = 1 of the [15.1] A″ state of CuOH, but no perturbations were observed for CuOD. Finally, a correlation diagram has been constructed, comparing the observed and calculated electronic states of the isoelectronic species CuF and CuOH.

Mass-independent Dunham analysis of the [13.8] Ω = 3/2 − X2Π3/2 transition of platinum monochloride, PtCl, observed by intracavity laser spectroscopy: Periodic trends in the M+X− bonding model (M = Ni, Pt; X = F, Cl)

The first electronic transition of platinum chloride, PtCl, observed at high resolution has been recorded in absorption using Intracavity Laser Spectroscopy (ILS). The PtCl molecules were produced in a current-regulated RF discharge formed when 0.30–0.60 A was applied to a Pt-lined Cu hollow cathode in a ∼1 Torr Ar/He sputter gas mixture, with a trace amount of CCl4 as the chloride source. The hollow cathode was located within the resonator cavity of either a tunable DCM dye laser operated over the 14,500–16,500 cm−1 range or a Ti:Sapphire laser operated over the 12,890–12,990 cm−1 and 13,255–13,365 cm1 ranges. Effective absorption path lengths ranging from 0.6 to 2.0 km were utilized with the ILS method. Eight band systems were identified and rotationally analyzed as the (0,2), (0,1), (3,0), (4,0), (5,0), (6,0), (6,1), and (7,1) vibrational bands of the [13.8] Ω = 3/2 − X2Π3/2 transition of PtCl. The vibrational assignment was confirmed through isotopologue shift analysis. The ILS data and millimeter- and submillimeter-wave data reported by Okabayashi et al. (2012) were fit to a mass-independent Dunham-type Hamiltonian using PGOPHER. Pt-isotope dependent deviations in the Dunham model were observed in Y″01(Be″), Y′01(Be′), and Y′00(Te′) and treated using field-shift parameters, and these parameters are compared to the reported field-shift effects for other 5d transition metal diatomics. The excited state molecular constants determined in this study are consistent with those of the (4) 3/2 state in the computational study by Zou and Suo (2016). The electronic transitions of NiF, NiCl, and PtF analogous to the [13.8] Ω = 3/2 – X2Π3/2 transition of PtCl have been studied both theoretically and experimentally. The vibrational force constants and relative bond lengths for the MX (M = Ni, Pt; X = F, Cl) molecules suggest that Ni and Pt form similar MX bonds, with NiX bonds being slightly stronger, but a large effect is observed for halogen substitution, with MF force constants being more than twice as large as the corresponding MCl values.

Amplification of the Fluorescence Propagating in the Waveguide Regime in a Planar Layer of NLC

The amplification of spontaneous fluorescence in a planar layer of nematic liquid crystal doped with DCM dye in the mode of waveguide light propagation has been studied. The gain reaches the value α = 0.0014 μm–1 at a pump radiation intensity of 1.38 MW/cm2. Numerical simulation of the structure imitating the experimental cell showed qualitative agreement of the calculation results with the experimental data.

Waveguide amplification of dye fluorescece in NLC

The amplification of spontaneous fluorescence in a planar layer of a nematic liquid crystal doped with a DCM dye is experimentally studied in a waveguide mode of light propagation. The optical pumping threshold of the superfluorescence is 0.65 MW/cm2. The gain value reaches 0.0014 μm-1 at a pumping intensity of 1.38 MW/cm2. Full Text: PDF ReferencesLiquid Crystal Microlasers, Eds. L. M. Blinov, R. Bartolino (Kerala India, Transworld Research Network 2010). DirectLink H. Kogelnik, C. V. Shank, "Coupled‐Wave Theory of Distributed Feedback Lasers", J. Appl. Phys. 43, 2327 (1972). CrossRef I. P. Il'chishin, E. A. Tihonov, V. G. Tishchenko, M. T. Shpak, "Generation of a tunable radiation by impurity cholesteric liquid crystals", JETP Lett. 32, 25 (1980). DirectLink A. Yariv, M. Nakamura, "Periodic structures for integrated optics", IEEE Quant. Electr. 13, 233 (1977). CrossRef N. M. Shtykov, M. I. Barnik, L. M. Blinov B. A. Umanskii, S, P. Palto, "Amplification of the emission of a liquid-crystal microlaser by means of a uniform liquid-crystal layer", JETP Lett. 85, 602 (2007). CrossRef

Identification and characterization of two new electronic states of PtF: Analysis of the (2,1), (1,0), (0,0), (0,1), (1,2), and (0,2) bands of the [15.8 + x] Ω = 5/2 − B2Δ5/2 transition

Several new electronic transitions of PtF have been observed in the high resolution spectra recorded in absorption using Intracavity Laser Spectroscopy (ILS). The PtF molecules were produced in a current-regulated RF discharge operating with 0.30–0.80 A applied to a Pt-lined Cu hollow cathode in 0.50–1.25 Torr of 1–5% SF6 in an Ar/He sputter gas mixture. This hollow cathode was located within the resonator cavity of a tunable DCM dye laser operating over the 14,500–16,500 cm−1 range, and effective pathlengths of 0.4–2.0 km were utilized with the ILS method. Six band systems were identified as the (2,1), (1,0), (0,0), (0,1), (1,2), and (0,2) bands of the [15.8 + x] Ω = 5/2 − B2Δ5/2 transition. Spectral features due to 194PtF, 195PtF, 196PtF, and 198PtF were identified, and the data were fit to mass-independent Dunham-type expressions using PGOPHER. A Pt-isotope field-shift correction to the electronic excitation energy was required to model the observed transitions to within experimental uncertainty. The results of this study indicate that the [0.4] 2Δ5/2 state reported by Ng et al. must be the A2Σ+ state of PtF, and the experimental findings correspond well with the theoretical predictions of Zou and Suo (2016).

Local environment of organic dyes in an ionic liquid-water mixture: FCS and MD simulation.

The composition dependent local environment of three organic dyes in binary mixtures of a room temperature ionic liquid (1-methyl-3-pentylimidazolium bromide, [pmim][Br]) and water is studied by fluorescence correlation spectroscopy (FCS) and molecular dynamics (MD) simulations. We used three dyes-neutral coumarin 480 (C480), anionic coumarin 343 (C343), and highly hydrophobic 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM)-to probe different environments in the binary mixtures. The heterogeneity of the [pmim][Br]-water mixture leads to multiple values (i.e., distribution) of diffusion coefficients (Dt). In these binary mixtures, the effective viscosity (ηeff, obtained from FCS) and the local concentration of the [pmim][Br] around the three dyes (revealed by MD simulations) are found to be quite different than that in bulk. The viscosity experienced by the C480 and C343 dyes is almost twice as large as that experienced by DCM dye. Through rigorous MD simulation, we show that in the vicinity of the less hydrophobic coumarin dyes (C480 and C343) compared to DCM dye, the local concentration of the [pmim][Br] is ∼3-7 times larger than that in bulk. In the case of the most hydrophobic dye, DCM, the local concentration of [pmim][Br] is almost similar to bulk-like. Further analysis reveals the formation of hydrogen bond between the imidazolium ring of [pmim][Br] and the carbonyl oxygen atom of the coumarin dyes (C-H[pmim][Br]⋯O=CDye). Finally, computer simulation indicates a slow component of solvation dynamics in the [pmim][Br]-water mixture in the time scale of ∼100-200 ps, which is similar to the experimental observation.

Effective control of two-photon absorption of DCM dye by solvent manipulation

The imaginary part of third-order nonlinear optical susceptibility (Imχ<3>) and two-photon absorption cross-section (σ2) of DCM dye dissolved in tetrahydrofuran, chloroform and dimethyl sulfoxide were obtained using nonlinear transmission method at 635 nm in ps regime.The Imχ<3> and σ2 values change with changing the solvent polarity parameter in the following way: and . However, in the case of DCM dissolved in chloroform, these values are about four times higher comparing with the parameters obtained for DCM dissolved in polar solvents. Therefore, using different solvents one can change, influence, enhance and control the nonlinear optical properties of DCM dye.