Red Laser Dye Research Articles

On the Luminescence Properties of Carbon Dots Synthesized on the Basis of Nile Red Laser Dye

On the Luminescence Properties of Carbon Dots Synthesized on the Basis of Nile Red Laser Dye

Nonmonotonic temperature dependence of fluorescence intensity of carbon dots in a glycerol solution

The effect of temperature on the fluorescence of carbon dot colloidal solution in glycerol has been studied. The dots were prepared by pyrolysis of a Nile Red laser dye using mesoporous silica as a template. It is established that the temperature dependence of the intensity of dominant emission peak is nontrivial: as the temperature of the solution rises, the initial quenching of the fluorescence is then replaced by its enhancement to the initial value. A three-level model of electronic states is considered, within which the observed temperature dependence of fluorescence is quantitatively described and the energies of nonradiative deactivation and activation of the emissive state are estimated. The nature of the electronic state responsible for the nonradiative activation of the emissive state is discussed. The possible influence of hydrogen bonds in the solute-solvent system on the temperature behavior of the CD fluorescence is also considered. A pronounced solvatochromic effect is noted in the fluorescence spectra of Nile Red based carbon dots in different solvents.

Synthesis and optical properties of 1-naphthol rhodamine for deep red laser dyes

In this study, we synthesized two asymmetric rhodamine laser dyes based on 1-naphthol (Dye-1 and Dye-2) and investigated their photophysical and laser performances. It was found that the fluorescence emission wavelengths of the two dyes are successfully extended to the deep red region. Compared with Dye-1, the esterification product Dye-2 displays a redshift of ∼8 nm in the maximum absorption wavelength (λabs) and fluorescence emission wavelength (λem). In aprotic solvents, both λabs and λem of Dye-2 red-shift with the increase of solvent polarity, while its fluorescence quantum yield always decreases with the increase of solvent polarity, no matter in protic solvents or aprotic solvents. The results of laser tests indicated that both Dye-1 and Dye-2 have wide laser tuning range and strong laser conversion efficiency in the red region. The laser conversion efficiency is closely relative to the dye concentration and linearly increases with the increase of pump laser energy.

Synthesis and properties of seminaphthorhodafluor red laser dyes

In the present work, we synthesized two seminaphthorhodafluor red laser dyes SNARF-X1 and SNARF-X2 and investigated their photo-physical properties in different solvents and the laser properties in ethanol. It was found that the wavelengths of absorption and fluorescence emission spectra are not very sensitive to the solvent polarity, while the fluorescence intensities decrease with the increase in solvent polarity. SNARF-X1 and SNARF-X2 not only emit tunable red laser (590–670 nm for SNARF-X1 and 600–680 nm for SNARF-X2) but also show high laser conversion efficiency. The above two dyes also show high photo-stability under 532 nm ND:YAG laser irradiation. In this regard, the half-lives of laser efficiency for SNARF-X1 and SNARF-X2 are 7 h and 6 h, respectively.

Deep‐Red Lasing and Amplified Spontaneous Emission from Nature Inspired Bay‐Annulated Indigo Derivatives

AbstractWhile noteworthy progress has been made on organic solid‐state lasers with low amplified spontaneous emission (ASE) thresholds and high optical gains in blue and green colors, the same advancement has not been achieved for red laser dyes. This is mainly due to their low photoluminescence quantum yields (PLQYs) because of “energy bandgap law.” Here, a new family of solution‐processable organic semiconductor laser dyes based on a bay‐annulated indigo derivative (Cibalackrot) with deep‐red emission is reported. They exhibit excellent PLQYs and low ASE thresholds (9.6 µJ cm−2) with deep‐red emission when blended in a mixed host of 1,3‐bis(N‐carbazolyl)benzene (mCP) and 2‐hydroxyphenylbenzothiazole (HBT). In contrast to a single blend in mCP, the co‐blend films are found to significantly enhance the photostability by retaining 90% of initial ASE intensity even after continuous pumping with over 9000 pulses at a pump input energy twice that of the ASE threshold, which can be attributed to efficient cascade energy transfer from mCP to HBT and then to the Cibalackrot chromophore. Low lasing threshold of 6 µJ cm−2 is further achieved at 641 nm by using distributed feedback gratings. Transient absorption spectroscopy measurements indicate that the dye has extremely low yield of triplet excited‐state under optical excitation. The results show Cibalackrot derivatives to be a promising new family of organic deep‐red laser dyes.

Grating-tuned dual-wavelength Nile red dye laser.

Dual-wavelength operation of grating-tuned dye laser systems was demonstrated in this paper. We used the second harmonic generation of a Q-switched Nd:YAG laser to pump the Nile red solvent (dissolved in ethanol) in the Littrow configuration and the Littman-Metcalf configuration. By rotating the grating 3.6° in the Littrow configuration and the tuning mirror 3.9° in the Littman-Metcalf configuration, we obtained a 72 and 46nm tuning-range dye laser output, respectively. Meanwhile by parallelly moving the grating in the Littrow configuration and the tuning mirror in the Littman-Metcalf configuration, we achieved the separation of dual wavelength from 0.7 to 5nm in the former and 1.5 to 4nm in the latter, which were in the terahertz range and could find applications in the terahertz source after using difference frequency technology. Finally, after considering the laser trajectories in the two configurations, we theoretically analyzed the reasons for overall tuning and separation tuning of dual wavelength.

Analysis of Inflammatory Mediators in Newborn Dried Blood Spot Samples by Chip-Based Immunoaffinity Capillary Electrophoresis.

A chip-based immunoaffinity capillary electrophoresis (ICE) system has been developed for measuring inflammatory mediators in dried blood samples routinely taken from newborn babies. A defined area of each dried blood spot was removed from the sample card and its contents eluted. The recovered eluates were injected into the chip and the analytes of interest isolated by the immunoaffinity disk within the chip. The captured analytes were labeled in-situ with a red light-emitting laser dye and electro-eluted into the chip separation channel. Electrophoretic separation of all of the analytes was achieved within 2.0min with quantification of each peak being performed by online LIF detection and integration of each peak area. The degree of accuracy and precision achieved by the chip-based system is comparable to conventional immunoassays and the system is robust enough to be applied to the analysis of clinical samples.

Tailoring the Molecular Skeleton of Aza‐BODIPYs to Design Photostable Red‐Light‐Emitting Laser Dyes

AbstractIn this article the design and characterization of a set of novel red‐light‐emitting laser aza‐BODIPY dyes is reported. The applied synthetic method allows an exhaustive and versatile functionalization of both the dipyrrin core and the boron bridge. From the analysis of the photophysical and laser signatures, we determine the suitable modifications of the chromophoric backbone necessary to modulate the emission spectral region, efficiency and photostability under a strong irradiation regime. These dyes are endowed with efficient fluorescence and laser emission, and are particularly outstanding in terms of their high photostability, a key parameter to guarantee long‐lasting emission in any (bio)technological application. The herein‐reported results support, for the first time, the viability of aza‐BODIPYs as tunable red laser dyes. In fact, the laser performances of some of the tested aza‐BODIPYs surpass those of commercially available laser dyes in the same spectral region.

Lasing of Some Red Laser Dyes in Annealed Silica Xerogel

The spectral and energy characteristics of generation in the red spectral region 650–720 nm were measured and analyzed for three laser dyes in preliminarily annealed SiO2 xerogel matrices under laser excitation λp = 588 nm in a nonselective cavity. The specific laser-energy output for two of them (LK678 and Ox170) in the matrices was 10–13% higher than in MeOH. NBA dye in the matrix generated two laser radiation bands in the 700–720 nm region with pumping Ep ≥ 80 mJ whereas its generation threshold in MeOH exceeded the maximum pumping energy of 140 mJ so that NBA generation was not observed. Laser emission spectra of the studied matrices in a nonselective cavity were red-shifted by ~1000 cm–1 from the fluorescence maximum. Such a shift could improve the characteristics of biosensors based on these matrices.

Concentration-dependent, simultaneous multi-wavelength amplified spontaneous emission in organic thin films using Förster resonance energy transfer

We have demonstrated amplified spontaneous emission (ASE) characteristics of binary blends with green and red laser dyes and ternary blends with three primary color laser dyes. The results show that the stimulated emission rate of donor can be balanced with the Förster resonance energy transfer from the donor to the acceptor by adjusting the doping concentration of donor or acceptor dye, leading to the realization of the multi-wavelength ASE. The binary blend emission is at 493 and 570 nm with threshold at 15.7 and 19.1 μJ/cm2, respectively, while the ternary blend emission is at 452, 510, and 596 nm with threshold at 22.0, 18.6, and 23.8 μJ/cm2, respectively.

Synthesis and spectroscopic properties of silica nanoparticles as scatter centers in random gain porous media

In this work, silica matrices have been synthesized and used as host for silica nanoparticles doped with Kiton Red laser dye using sol–gel technique. The bulk samples of KR–SiO2 nanoparticles confined in silica xerogel matrix have been prepared as a function of SiO2 nanoparticle sizes and concentrations. Different SiO2 particle sizes have been obtained by varying the pH value of starting silica precursor sol and determined using field emission scanning electron microscope. The structural characteristics of such matrices have been determined through FTIR spectra. Amplified spontaneous emission, threshold pumping energy, and mean free path for photons in the prepared random gain media have been reported. As a result, the best values of FWHM and threshold pumping energy, 8.7 nm and 12 mJ, have been observed for the sample prepared with 33.4 nm size and 2 wt% concentration of SiO2 nanoparticles. Comparison between the intensity of normal fluorescence spectrum (excited with CW laser diode 532 nm) and ASE spectrum (excited at 40 mJ pumping energy of 2nd harmonic Nd: YAG pulse laser 532 nm), Relation of both the bandwidth at FWHM and the peak fluorescence intensity as a function of pumping energy, Eth is the pumping threshold energy.

The energy transfer mechanism of a photoexcited and electroluminescent organic hybrid thin film of blue, green, and red laser dyes.

Though optically pumped lasing has been realized for years, electrically pumped lasing has not yet been achieved in organic semiconductor devices. In order to make a better understanding of the laser mechanisms of the organic materials, we prepared organic thin films consisting of three efficient laser dyes of a blue emitter, 4″,4″′-N,N-diphenylamine-4,4′-diphenyl-1,1′-binaphthyl (BN), a green emitter, 1,4-bis[2-[4-[N,N-di(p-tolyl)amino] phenyl]vinyl]benzene (DSB), and a red emitter, 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidy-l-9-enyl)-4H-pyran (DCJTB) with different doping concentrations for the first time to investigate the cascade energy transfer process. The energy transfer schemes in the co-doped thin films in photoluminescence and electroluminescence have been investigated. The results indicated that the DSB molecules acted as a bridge to deliver energy more effectively from the host (BN) to the guest (DCJTB). Meanwhile, the maximum current efficiency (CE) and power efficiency (PE) of the organic light-emitting devices (OLEDs) with the emitting layer of lower doping concentration were 13.5 cd/A and 14.1 lm/W, respectively.

Solid state solvation effect and reduced amplified spontaneous emission threshold value of glass forming DCM derivative in PMMA films

Molecule crystallization is one of the limitations for obtaining high-gain organic laser systems. One of the examples is well known red laser dye 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). The lowest threshold value of amplified spontaneous emission was achieved by doping 2wt% of DCM molecule in tris-(8-hydroxy quinoline) aluminum (Alq3) matrix. Further increase of the DCM dye concentration makes the system less efficient as its threshold value increases. It is due to large intermolecular interaction, which induces photoluminescence quenching. Compounds with reduced intermolecular interaction could be prospective in organic laser systems due to higher possible doping.In this work photoluminescence and amplified spontaneous emission properties of modified DCM molecule in poly(methyl methacrylate) (PMMA) matrix were investigated. Bulky trityloxyethyl groups were attached to the donor part of DCM. These groups increase intermolecular distance wherewith reduce photoluminescence quenching. More than one order of magnitude lower excitation threshold energy of the amplified spontaneous emission was achieved in doped polymer films with investigated compound in comparison to doped polymer with DCM. It means that the investigated compound is more perspective as a laser material compared to the previously studied. In addition, amplified spontaneous emission maximum could be tuned within 15nm by changing concentration from 0.1wt% to 10wt% DWK-1 in PMMA matrix due to solid state solvation effect.

Detection of cerebral spinal fluid‐associated chemokines in birth traumatized premature babies by chip‐based immunoaffinity CE

A major concern in treating premature infants with birth-associated head trauma is the rapid determination of reliable biomarkers of neuroinflammation. To this end a chip-based immunoaffinity CE device has been applied to determine the concentrations of inflammation-associated chemokines in samples of cerebral spinal fluid collected from such subjects. The chip utilizes replaceable immunoaffinity disks, to which reactive antibody fragments (FAb) of six antichemokine-specific antibodies were immobilized. Following injection of a sample into the device, the analytes were captured by the immobilized FAbs, labeled in situ with a red laser dye, chemically released and separated by CE. Each resolved peak was measured on-line by LIF detection and the results compared to standard curves produced by running known chemokine standards through the immunoaffinity system. The complete processing of a sample took 10 min with separation of all six analytes being achieved in less than 2 min. The system compared well to commercial ELISA, analysis of the results by linear regression demonstrating r(2) values in the range of 0.903-0.978, and intra and interassay CV of the migration times and the measured peak areas being less than 2.3 and 5%, respectively. Application of the system to analysis of cerebrospinal fluid from head traumatized babies clearly indicated the group with mild trauma versus those with severe injury. Additionally, CE analysis demonstrated that the severe trauma group could be divided into individuals with good and poor prognosis, which correlated with the clinical finding for each patient.

Joint mapping of bed elevation and flow depth in microscale morphodynamics experiments

Experiments conducted at very small scales are increasingly being used to study the morphodynamics of sediment beds under the action of flowing water. For such microscale experiments, we propose a measurement approach aimed at jointly mapping the evolving bed topography and distribution of water depth. The proposed measurement system includes a single color camera, a red stripe laser and green fluorescent dye. The stripe laser is scanned back and forth over the experimental surface, while the fluorescent dye is mixed with the flowing water, allowing both the bed topography and water depth to be reconstructed from color images. We present the steps needed for image calibration and processing, including simple models of light refraction and attenuation. The methods are verified using a surface of known geometry, then demonstrated for a challenging groundwater channelization experiment. For this application, co-registered maps of bed topography and water depth are obtained at millimetric resolution for an experimental domain of 650 mm by 650 mm, at a rate of one pair of maps per minute (experimental time). The methods are found to yield accurate results and vividly depict the evolution of a self-formed channel network.

Two-photon excitation of phenalemine 512 by nanosecond pulses of a Nd:YAG laser

The two-photon absorption cross section of the efficient red laser dye 6-(Cyclohexylamino)-3-triflurometyl-1H-phenalen-1-one (phenalemine 512) in ethanol and polymethyl methacrylate excited by nanosecond pulses from a 1064-nm Nd:YAG laser is measured by the method of two-quantum standard. Lasing in phenalemine 512 is obtained upon two-photon excitation of the dye in solutions, a polymer matrix, and drops.

Rapid analysis of inflammatory cytokines in cerebrospinal fluid using chip-based immunoaffinity electrophoresis.

A chip-based capillary electrophoresis system has been designed for rapidly measuring the concentrations of inflammatory cytokines in the cerebrospinal fluid of patients with head trauma. Isolation of the reactive cytokines was achieved by immunoaffinity capture using a panel of six immobilized antibodies, directly attached to the injection port of the chip. The captured cytokines were labeled in situ with a red light-emitting laser dye and electroeluted into the separation channel. Separation of the isolated cytokines was achieved by electrophoresis in under 2 min with quantification of the resolved peaks being achieved by on-line laser-induced fluorescence and integration of each peak area. Comparison of the results to commercially available high-sensitivity immunoassays demonstrates that the chip-based assay provides a fast, accurate procedure for studying the concentrations of these analytes in complex biological materials. The degree of accuracy and precision achieved by the chip-based CE is comparable to conventional immunoassays, the system being able to analyze between 10-12 samples per hour. With the ever-expanding array of antibodies that are commercially available, this chip-based system can be applied to a wide variety of different analyses.

Solid state solvation in amorphous organic thin films.

The photoluminescence (PL) of the red laser dye DCM2, doped into blended thin films of polystyrene (PS) and the polar small molecule camphoric anhydride (CA), redshifts as the CA concentration increases. The DCM2 PL peaks at 2.20 eV (lambda=563 nm) for pure PS films and shifts to 2.05 eV (lambda=605 nm) for films with 24.5% CA (by mass). The capacitively measured electronic permittivity also increases from epsilon=2.4 to epsilon=5.6 with CA concentration. These results are consistent with the theory of solvatochromism developed for organic molecules in liquid solvents. To our knowledge, this work is the first application of a quantitative theory of solvation to organic molecules in amorphous thin films with continuously controllable permittivity, and demonstrates that "solid state solvation" can be used to predictably tune exciton energies in organic thin film structures.

Nile Red and DCM Fluorescence Anisotropy Studies in C12E7/DPPC Mixed Systems

The lipid/surfactant mixed interactions between the lipid dipalmitoylphosphatydilcholine (DPPC) and the nonionic surfactant C12E7 (C12H25(OCH2CH2)7OH) were studied by the use of fluorescence anisotropy of nile red and DCM laser dye. Three different regions consisting of mixed micelles, mixed vesicles, and both aggregates were identified. Nile red fluorescence anisotropy is wavelength-dependent, the spectra being decomposed into two log-normal functions. These results are consistent with a solvent relaxation process, with distinct anisotropies for the relaxed and unrelaxed states. The spectral properties (anisotropy and maximum emission wavelength) of the relaxed state show higher sensitivity to the environment than those of the unrelaxed state. DCM fluorescence anisotropy shows similar trends. This was interpreted as a result of a trans−cis photoisomerization process. The observed anisotropy spectrum was decomposed in two Gaussian functions reflecting a distinct anisotropy for each isomer.

White organic light-emitting diodes emitting from both hole and electron transport layers

Some white emitting organic light-emitting diodes (LED) have been made by inserting a carrier block layer, diphenyl- p-( t-butylphenyl-1,3,4-oxadiazole (PBD), between a blue emissive ( N- p-methoxylphenyl- N-phenyl)- p-methoxylphenyl-styrylamine (SA) layer and a green emissive 8-hydroxyquinoline aluminium chelate layer or a red emissive laser dye 4-dicyanomethylene-2-methyl-6-( p-dimenthyaminostyryl)-4 H-pyran (DCM)-doped Alq3 layer. The electroluminescent (EL) behaviours of the diodes have been investigated. It is found that the emission colour of the diode varies depending on the thickness of PBD layer in the devices. By choosing the thickness of PBD film, we can obtain near white emitting diodes. The emissions from the triple-layer devices are found be emitted from both SA and Alq3 or Alq3:DCM layers, which are situated in the two sides of PBD, by analysing the spectra of the devices with different thicknesses at different applied voltage.