Extinction Coefficient Values Research Articles

New Yellow Azo Pyridone Derivatives with Enhanced Thermal Stability for Color Filters in Image Sensors

Two new yellow azo pyridone derivatives, (E)-6-hydroxy-1-(3-methoxypropyl)-4-methyl-2-oxo-5-(p-tolyldiazenyl)-1,2-dihydropyridine-3-carbonitrile (APY-M) and 5,5′-((1E,1′E)-(methylenebis(4,1-phenylene))bis(diazene-2,1-diyl))bis(6-hydroxy-4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile) (APY-D), were designed and synthesized as yellow colorants for image sensors. The properties of these new compounds were evaluated in both solution and color filter film forms, focusing on their optical and thermal characteristics. The molar extinction coefficient values of APY-M and APY-D in solution were found to be 2.7 × 105 and 3.0 × 105 L/mol·cm, respectively. The transmittance of the newly synthesized compounds met commercial requirements, showing values below 0.21% at 435 nm and above 97.1% at 530 nm. APY-D exhibited a molar extinction coefficient value in solution that was 1.15 times higher than that of the commercially used yellow colorant Disperse Yellow 241. Both newly synthesized compounds satisfied the decomposition temperature requirement of over 230 °C, which is essential for the color filter manufacturing process in image sensors. In particular, APY-D, with its dimeric structure and increased molecular weight, demonstrated enhanced thermal stability, with a 50 °C increase in decomposition temperature compared to Disperse Yellow 241. Color filter films for image sensors were fabricated using the new compounds, and their thermal resistance was evaluated. APY-D maintained its transmittance due to the enhanced thermal stability provided by its dimer structure and increased molecular weight. Consequently, APY-D is anticipated to be a promising candidate for use as a yellow colorant in image sensors, owing to its excellent optical and thermal properties.

Effects of cadmium doping on the physical and sensing properties of nanostructured CuO thin films

This investigation used sol-gel deposition to create undoped CuO and CuO: Cd thin films. All films of undoped CuO and CuO: Cd phase exhibit four dominating peaks at 35.52°, 38.84°, 53.37°, and 68.23°, which are correspondingly assigned to the (022), (200), (020), and (220) planes, according to X-ray diffraction analysis. The dislocation density reduced from 60.55 to 49.94, the strain decreased from 26.98 to 24.60, and the grain size of the produced films measured by XRD was 12.85–14.15 nm. Atomic force microscopy (AFM) was used to study the morphology. SEM analysis showed increased aggregation with higher Cd content, resulting in a more uniform porous structure. The optical band gap decreases for all samples as the cadmium content increases, ranging from 2.28 to 2.14 eV. Similarly, the refractive index and extinction coefficient values decrease as the cadmium content increases for all samples. The gas sensor detects H2 (375 ppm) using CuO film cadmium doping, which enhances sensitivity, CuO: 4% exhibits highest resistance. Sensitivity decreases with higher doping, indicating reduced sensor responsiveness.

Optical analysis of ferrite films using spectroscopic ellipsometry

This work presents the optical properties of nickel zinc ferrite, nickel copper zinc ferrite, and nickel cobalt zinc ferrite films prepared on Si/SiO2 substrates using the sol-gel and spin-coating technique. A J.A. Woollam Company RC2 model D variable angle spectroscopic ellipsometer was used to measure the amplitude ratio (Ψ) and phase difference (Δ) of the films annealed at two distinct temperatures (500 and 800 °C). Measurements were taken at three incident angles (55°, 65°, and 75°) across the spectral range of 190–1000 nm, with a step size of 1 nm. The acquired data were subjected to modeling using a summation of Kramers–Kronig consistent oscillators to determine the film thickness and complex optical functions (refractive index and extinction coefficient) with a minimized mean-squared error. Additionally, incorporating a surface roughness layer notably enhanced the accuracy, with the roughness described using the Bruggeman effective medium approximation reflecting a 50%–50% mixture between the film's optical constants and those of air (void). The experimental and simulated (Ψ, Δ) spectra as a function of wavelength at angles 55°, 65°, and 75° for the NZF, NCuZF, and NCoZF films annealed at 500 and 800 °C are provided. The refractive index and extinction coefficient values as a function of wavelength for NZF, NCuZF, and NCoZF films annealed at 500 and 800 °C are also included. The elucidated optical properties of these films hold potential for application in various optoelectronic devices, including solar cells.

Identifying orientation-dependent optical properties of single-crystalline β-Ga2O3 films

We explore the effect of crystallographic anisotropy on the optical properties of high-quality β-Ga2O3 thin films by conducting experimental measurements and theoretical simulations. High resolution x-ray diffraction measurements confirm the high-quality and the single crystalline quality, ruling out the effect of defects for all films. Raman spectra reveal the presence of anisotropy, as evident from a stronger Bg(2) mode related to GaIO4 chain libration in (100) orientation. Conversely, a stronger Ag(10) mode corresponding to tetrahedral bonds is evident in the (010) orientation, while it is suppressed in the (100) orientation. Low-temperature photoluminescence spectra indicate the presence of intrinsic impurity-related emissions in the ultraviolet and blue regions for all films. An anisotropic bandgap is observed, wherein the lowest bandgap value is related to the (010) oriented sample. Spectroscopic ellipsometry measurements confirm different refractive indices and extinction coefficient values depending on crystallographic orientation, which are in good agreement with the theoretical values obtained by density functional theory, confirming the anisotropic characteristics. The theoretical calculations of charge density show that the strength of covalent bonding depends on the β-Ga2O3 orientation, while experimental findings demonstrate that as the covalent bonding character increases, the film bandgap and the refractive index decrease. The anisotropy of β-Ga2O3 with respect to the crystal orientation leads to variations in the extinction coefficient, refractive index, and bandgap energy.

Optical and Dielectric Features of PVA/CMC/PVP/ZnMn2O4/CuCo2O4/x wt% MWCNTs Blended Polymers for Optoelectronic Applications

This study is devoted to optimizing the optical and dielectric parameters of polyvinyl alcohol (PVA)/ carboxymethyl cellulose (CMC)/ polyvinylpyrrolidone (PVP) blended polymer by adding ZnMn2O4/CuCo2O4 nanocomposite and controlling the amounts of multi-walled carbon nanotubes (MWCNTs) to engage them in flexible optoelectronics and storage energy capacitors. Herein, 0.9ZnMn2O4/0.1CuCo2O4 was synthesized by co-precipitation and hydrothermal methods and loaded with different ratios of MWCNTs into PVA/CMC/PVP blend to produce films by solution casting procedure. The crystallite size of 0.9ZnMn2O4/0.1CuCo2O4 was determined using transmission electron microscopy. The structures of the filler and doped blends were explored via the X-ray diffraction technique. The optical features of undoped and doped blends were explored by diffused reflectance and fluorescence spectrophotometers. The addition of ZnMn2O4/CuCo2O4 to PVA/CMC/PVP caused a decline of direct and indirect optical band gaps from 5.33 and 5.03 eV to 5.19 and 4.66 eV, respectively. By adding different amounts of MWCNTs, the direct/indirect optical band gap reduced irregularly, and they attained their minimum values (5.07, 4.46) eV as it doped with 0.6 Wt% MWCNTs. The highest values of refractive index, extinction coefficient, optical conductivity and nonlinear optical parameters were achieved in the blend containing ZnMn2O4/CuCo2O4/0.6 Wt% MWCNTs. It is also found that the dielectric constant and ac conductivity rose with the insertion of ZnMn2O4/CuCo2O4/0.6 Wt% MWCNTs. The highest energy density value was found in the polymer blend of PVA/CMC/PVP/ZnMn2O4/CuCo2O4/0.8 Wt% MWCNTs blended polymer. Electrical modulus and Nyquist plots for different blends were also examined. The results recommend the doped blends as a good candidate for optoelectronics and energy storage capacitor applications.

Atmospheric extinction coefficients and night sky brightness at ITB-Undana remote telescope site

Abstract A remote telescope system has been established at Universitas Nusa Cendana, Kupang. Bosscha Observatory, Institut Teknologi Bandung (ITB), and the Physics Study Program at Universitas Nusa Cendana (Undana) collaborated to develop the system. The ITB-Undana Telescope system has a QSI 616 CCD camera and BV RI Bessel filter attached to a 20-cm (f/10) Schmidt-Cassegrain reflector. Several research and public outreach activities have been conducted using the ITB-Undana remote telescope throughout 2023. When establishing a new astronomical observation site, it is imperative to conduct sky characterization and quality assessment. This process involves measuring night sky brightness and atmospheric extinction coefficients. In May 2023, we observed photometric standard stars using the absolute photometry technique with BV RI Bessel filters. We also utilized the Sky Quality Meter (SQM) to measure night sky brightness over three nights from May 24th to May 26th, 2023, to compare the sky brightness values obtained through the absolute photometry method. Our initial measurement shows a first-order extinction coefficient value ranging from k b ′ = 0.269 to 0.520, k v ′ = 0.216 to 0.297, k r ′ = 0.019 to 0.206, and k i ′ = 0.127 to 0.163, for B, V, R, and I filter, respectively. Application of extinction coefficient value in the sky field gives a mean sky brightness value in V bandpass, V sky = 19.431 ± 0.022, with color index (B − V )sky = 0.492 ± 0.039. These night sky brightness values are suitable for measurements using the SQM.

DEVELOPMENT AND VALIDATION OF METHODS FOR THE SPECTROPHOTOMETRIC DETERMINATION OF PROSPIDIUM CHLORIDE FOR IDENTIFICATION AND ASSAY ANALYSIS

Objective. The work is devoted to the development and validation of UV-spectrophotometric analysis of propidium chloride, an antitumour drug of the dyspyropiperazine group. The relevance of the study is due to the need to introduce into the practice of quality control of prospidium chloride analysis method characterised by high sensitivity, accuracy, rapidity and availability. Material and methods. The object of the study was a medicinal substance-powder Prospidin (Prospidium chloride, series 271222, expiry date until 12.2027g, produced by «Unitehprom BSU», Minsk). Solutions with working concentration range from 0.05 mol/l to 0.2 mol/l for spectrophotometric analysis were prepared using purified water. Absorption spectra with determination of analytical wavelength (λmax, nm) and value of molar absorption coefficient ε, (l mol-1cm-1) in the range from 200 nm to 400 nm were obtained and analysed on Agilent Cary 60 equipment. Validation parameters were determined in accordance with the regulations of the General Pharmacopoeial Article 1.1.0012.15. Results. Validation evaluation of the developed analytical techniques for the determination of authenticity and active ingredient content by UV spectro-photometry included tests for specificity (in the presence of NaCl 0.9% solution), analytical range (0.05−0.2 mol/L), linearity (r=0.9997), accuracy, preci-sion in terms of repeatability 3.89±0.24 ( ±SD) and intra-laboratory reproducibility (ε=2.1%) and stability. Conclusion. The analysis of electronic spectra of aqueous solutions of propidium chloride demonstrated the presence of R-band absorption (German radikalartig − radical, for systems with unshared electron pairs) with a characteristic wavelength in the far-UV region at λmax=282±0.4 nm, and λmin=255±0.4 nm. It was found that the absorption at λmax in the concentration range from 0.05 mol/L to 0.2 mol/L of a solution of propidine chloride containing nitrogen heteroatoms with unshared electron pairs is due to the implementation of the so-called formally forbidden n→σ* electronic transition involving molecular orbitals. The characteristic appearance of the electronic spectrum with λmax and λmin, compliance with the Beer–Lambert law in the given concentration range, the calculated value of the molar extinction coefficient ε (l mol1cm1) − allow to use the above described spectral characteristics to determine the authenticity and content of the active substance in quality control of prospidium chloride.

Enhancing instrumental sustainability: a spectrophotometric approach for quantifying iodate in nutritionally significant salts through the adaptation of the classical iodometry method

With the primary objective of transitioning from the classical iodometric method to an instrumental approach, preserving precision in the analytical process, this study presents the development of a spectrophotometric method for quantifying iodate (iodine equivalent) in nutritionally significant salts. Therefore, the wavelengths of maximum absorption of the I3- (350.8 nm) and I3-starch (574.1 nm) complexes were determined. The complexes demonstrated stability, as indicated by the respective molar extinction coefficient values (ε) obtained over the course of the reaction time (measured up to 1h, at 5-minute intervals, and at 28°C), for concentrations ranging from 7.81×10-6 to 1.25×10-4 mols/L of KIO3. A linear correlation between concentration and absorbance was established within the specified concentration range, with detection and quantification limits defined as 0.09 and 0.29 mg/L (350.8 nm) and 0.13 and 0.39 mg/L (574.1 nm), respectively, and calculated recovery of 102.9%. The reproducibility of the method was assessed by varying the analyst, the equipment, and the analysis day. Using the developed method, it became feasible to quantify the elemental iodine equivalent in three commercially available salts commonly employed for food purposes. When compared to the classical/traditional iodometric method, the spectrophotometric method for quantifying iodate in salts showcases sustainability with minimized solvent and reagent usage, reduced waste generation, shorter analysis time, and lower sample requirements, aligning with environmentally conscious analytical practices.

Determination of Optical Properties of Commercial Thin Film Polymers Used for Solar Protection Applications

A procedure is proposed to determine the optical properties of commercial polymeric films used as solar control for building skins. The spectral variation (190-1100 nm) of the refractive index and extinction coefficient of the samples was obtained through the simulation of the experimental transmittance spectra of the samples. Polyvinyl chloride (PVC) and polyethylene terephthalate (PET) films were analyzed. Refractive index values between 1.1 and 2.5 at λ = 500 nm and extinction coefficient values of 104 cm-1 in the ultraviolet (UV) region were found. All these results show a good fit with those given in the literature for similar thin films. A new concept for the illumination and temperature control of buildings by the use of polymeric thin films as a transparent solar protection material is presented.

The radiative impact of biomass burning aerosols on dust emissions over Namibia and the long-range transport of smoke observed during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) campaign

Abstract. The radiative effects of biomass burning aerosols (BBAs) on low-level atmospheric circulation over southern Africa are investigated on 5 September 2017 during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) field campaign. This is conducted using a variety of in situ and remote sensing observations, as well as two 5 d ensemble simulations made with the Meso-NH mesoscale model, one including the direct and semi-direct radiative effects of aerosols and one in which these effects are not included. We show that the radiative impact of BBA building up over a period of 5 d in the Meso-NH simulations can lead to significantly different circulations at low and middle levels, thereby affecting dust emissions over southern Namibia and northwestern South Africa as well as the transport of BBA in a so-called “river of smoke”. While most of the regional-scale dynamics, thermodynamics and composition features are convincingly represented in the simulation with BBA radiative effects, neglecting the radiative impact of BBA leads to unrealistic representations of (i) the low-level jet (LLJ) over the plateau, which is the main low-level dynamic feature fostering dust emission, and (ii) the mid-level dynamics pertaining to the transport of BBA from the fire-prone regions in the tropics to the mid-latitudes. For instance, when the BBA radiative impacts are not included, the LLJ is too weak and not well established over night, and the developing convective planetary boundary layer (PBL) is too deep compared to observations. The deeper convective PBL over Etosha and surrounding areas is related to the enhanced anomalous upward motion caused by the eastern displacement of the river of smoke. This eastern displacement is, in turn, related to the weaker southerly African easterly jet. Both ensemble simulations provide clear evidence that the enhanced near-surface extinction coefficient values detected from observations over Etosha are related to the downward mixing of BBA in the developing convective boundary layer rather than dust being emitted as a result of the LLJ breakdown after sunrise. This study suggests that the radiative effect of BBAs needs to be taken into account to properly forecast dust emissions in Namibia.

Linear and non-linear optical and dielectric properties of transition metals complexes films derived from Azo-Schiff base for photovoltaic applications

A novel azo-Schiff base, which incorporates a heterocyclic triazole nucleus known as 1H-1,2,4-triazol-5-yl)imino)methyl)-5-((2-nitrophenyl)diazenyl)phenol (H2ASB, 1), was formulated and synthesized. Furthermore, a series of Cu2+ complexes, derived from this azo-Schiff base, were prepared by a simple method with a molar ratio of 1 M Cu2+ to 1 M H2ASB. The synthesized compounds were thoroughly characterized using alternative analytical and spectral techniques. The obtained results confirmed that H2ASB bonded with the Cu2+ ions in a uni-negative/neutral bidentate manner, via the phenolic hydroxyl oxygen and azomethine nitrogen atom, thereby resulting in tetrahedral or octahedral geometries. Additionally, theoretical studies employing DFT/B3LYP/LanL2DZ were conducted, which included the assessment of global reactivity descriptors, dipole moment, molecular electrostatic potential image (MEP), optimized geometry, and the LUMO-HOMO energy gap to support the geometrical structure of the synthesized compounds. On the other side, the optical constants of H2ASB and its complexes have been studied over 300–1500 nm spectral range. The optical band gap (Eg) values of the present film's changes from 1.92 eV for H2ASB to 1.45 eV for CuHASB(5) film whereas the static index of refraction (n) takes a different behavior. The obtained values of n and Eg are the same as those recorded for many semiconductor materials. This means that, compared to the cost and ease of preparation, these films under study could replace many other semiconductors, such as CdTe with (Eg = 1.5 eV) which is the same value of CuHASB(4) film. With the help of n and extinction coefficient (k) values, the dielectric and non-linear optical parameters have been estimated and well discussed. Finally, the sheet resistance (Rs) and thermal emissivity (εth) changes due to the incident photon energy have been investigated. It was observed that, the change of Rs and εth with E is opposite to the change of other parameters such as the absorbance and optical conductivity.

Analysing the suitability of CaTiO3/Ca1–xSrxTiO3/SrTiO3 perovskite for fabrication of optoelectronic devices using QuantumATK tool: a study for electronic and optical properties

Calcium Titanate (CaTiO3) as a material has been researched for various applications like those in capacitors, piezoelectric devices and ceramic applications. Same has been possible owing to the exhibition of various characteristics of this material like high melting point (1,625 °C) and dielectric properties. However, only limited studies have been conducted to understand the impact of Strontium (Sr) doping and possibility of adopting this material into any kind of optoelectronic applications. This paper carries on an in-depth analysis on CaTiO3 and study effect of Sr as a dopant on its properties. Analysis has been carried out using Quantum ATK tool based on DFT approximations. CaTiO3 perovskite properties were studied by using the GGA (Generalized Gradient Approximation) and PBE (Perdew–Burke–Ernzerhof) functionals, which are used with the LCAO calculator. As a result of the inclusion of Sr at the Ca site, the electronic band structure of CaTiO3 was changed by the introduction of a gamma point. Bandgap of CaTiO3 was analysed to be dependent on the Sr site concentration and increased from 2.3 eV (Direct bandgap) to 2.3612 eV (Indirect bandgap), when Sr and Ca site concentration were equal, but it decreased with further increase in Sr site concentration to 1.7155 eV. Pure CaTiO3’s projected density of states changed after doping, providing evidence for the effects of the dopant on the system. As a result of an examination of the optical properties of both systems, it is found that CaTiO3 at 380 nm (close to infrared) exhibits an effective extinction coefficient (k) value of 0.78, whereas at 600 nm, the attenuation of light decreases to zero. This makes Sr doping in CaTiO3 another attractive candidate for optical devices in addition to its ability to change optical properties.

Investigations on Chemically Synthesized Pure and Doped Manganese Dioxide Nanoparticles for Dye Removal and Photocatalytic Applications.

Pure and Mg2+, Ni2+, Cd2+ doped MnO2 nanoparticles were synthesized by chemical co-precipitation method. These samples were characterised by PXRD, SEM, EDX, FTIR, UV-Vis-NIR, PL, Antibacterial, Cyclic Voltammetry, Dye Degradation and Photocatalytic studies. From the powder XRD studies, the crystallite size of the particle was calculated using Scherer formula and found that the synthesized nanoparticles were in the range from 10 to 12nm. The morphology of all the synthesized samples was viewed from SEM micrograph. The composition and purity of the samples were identified from EDX studies. In FTIR spectra metal-oxygen stretching and bending modes of vibrations were observed. From the absorption spectra of UV-Vis optical analysis values of absorption coefficient, extinction coefficient, refractive index, real and imaginary part of optical dielectric constant and optical conductivity were compared. The band gap energy obtained from Tauc's plot varies from 1.21 to 1.51eV exhibits semiconducting behaviour of all the synthesized samples. Investigations on photoluminecsence spectrum reveals blue shift in wavelength for doped nanooxides compared to pure MnO2. Antimicrobial activity of synthesised samples against gram positive and gram negative bacteria was determined. The obtained results reveal very high bacterial resistance in Cd2+ doped MnO2 nanoparticles with higher activity towards bacterial resistance compared to standard drug. The specific capacitance values were determined from Cyclic Voltammetry studies. Using the batch method of dye removing technique the percentage of malachite green dye removal was calculated. Also the photocatalytic efficiency of all the synthesized MnO2 samples in removing malachite green dye was studied by exposing to sunlight for different dosage and contact time. Ni2+ doped MnO2 shows relatively higher % of dye degradation capacity about 93% for 0.1g of dosage of photocatalysts.

Photochemical Povarov-type Reactions: Electron Donor-Acceptor Photoactivation by Visible Light.

This report investigates the mechanism of photochemical Povarov-type reactions of N,N-dialkylanilines and maleimides in polar solvents (DMF or dioxane) in the presence of light. Fundamental aspects of the electron donor-acceptor (EDA) photoactivation pathway proposed to underpin this chemistry are examined through integrated experimental and computational studies. This approach provided evidence supporting the involvement of an EDA complex in facilitating this chemistry via a reaction mechanism that does not involve a triplet manifold. Most notably, our findings indicate that relying solely on UV-vis absorption spectroscopic data to either account for or predict reactivity in synthetic experiments may not always provide the complete picture. More specifically, this relates to considering UV-vis absorption spectroscopic data, calculated values for association constants (KEDA) and molar extinction coefficients (ε), with the reactivity observed in associated synthetic reactions in practice.

Enhanced Optical and Thermal Properties of a Novel Yellow Quinophthalone Derivative for Color Filter Colorants in Image Sensors

Herein, the design and synthesis of novel yellow quinophthalone derivatives, 4,5,6,7‐tetrachloro‐2‐(6‐chloro‐2‐(3‐hydroxy‐1‐oxo‐1H‐cyclopenta[b]naphthalen‐2‐yl)quinolin‐4‐yl)isoindoline‐1,3‐dione (pC‐QP) and 4,5,6,7‐tetrachloro‐2‐(7‐chloro‐2‐(3‐hydroxy‐1‐oxo‐1H‐cyclopenta[b]naphthalen‐2‐yl)quinolin‐4‐yl)isoindoline‐1,3‐dione (mC‐QP), are used for use as yellow colorants in image sensors. The synthesized compounds are designed to modulate the optical properties based on the substituted positions of the chloride group within the quinophthalone structure. The solubility of pC‐QP and mC‐QP in propylene glycol monomethyl ether acetate solvent is found to be 0.08 and 0.15 wt%, respectively. The molar extinction coefficient values of pC‐QP and mC‐QP in solution are determined to be 3.14 × 104 and 3.62 × 105 L mol−1 cm−1, respectively. The transmittance of mC‐QP meets commercial requirements, exhibiting less than 0.3% between 412 and 475 nm and over 91% above 530 nm. Both pC‐QP and mC‐QP demonstrate high thermal stability with decomposition temperatures of 464 and 393 °C, respectively. As a result, mC‐QP emerges as an excellent candidate material for use as a yellow colorant in image sensors due to its outstanding properties.

Enhancing saturable absorption in a Au-decorated MoS2/PEDOT:PSS nanocomposite through plasmon resonance and Pauli blocking.

We have effectively demonstrated a technique for substantial alteration of the nonlinear saturable absorption (SA) properties in nanocomposite films (NCF) composed of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) and molybdenum disulfide (MoS2) decorated with gold nanoparticles (AuNPs). This control is achieved by adjusting the AuNP concentration on the MoS2 surface and varying the input pulse energy of the laser. The simple drop-casting method is used to create the nanocomposite films (NCFs) on a glass substrate with different amounts of Au-decorated MoS2. The Kramers-Kronig equations are employed for determining the refractive index and extinction coefficient values of the resulting NCFs. Nonlinear investigations reveal that adding Au-decorated MoS2 to pure PEDOT:PSS alters its optical nonlinearity. Surface plasmon resonance and Pauli blocking have been observed in Au-decorated MoS2/PEDOT:PSS NCFs. This increases NCF's saturable absorption. An open aperture Z-scan method is utilized to study nonlinear optics, with excitation achieved using a nanosecond (ns) pulsed laser operating at a 532 nm wavelength. The findings reveal the noteworthy saturable absorption characteristics of the NCFs.

Green synthesis of ethyl cinnamates under microwave irradiation: photophysical properties, cytotoxicity, and cell bioimaging.

A simple and green method for the synthesis of six ethyl cinnamates was performed via Horner-Wadsworth-Emmons reaction under microwave irradiation. The photoluminescent properties of all compounds in ethyl acetate solutions were evaluated demonstrating that all compounds exhibit fluorescence. Five compounds exhibited blue emissions in the 369-442 nm range, and another compound exhibited blue-green emission at 504 nm. This last compound showed the largest Stokes shift (134 nm), and the highest quantum yield (17.8%). Two compounds showed extinction coefficient values (ε) higher than 30 000 M-1 cm-1, which are appropriate for cell bioimaging applications. In this sense, cytotoxicity assays were performed using Vero cells at different concentrations; the results showed that these compounds were not cytotoxic at the highest concentration tested (20 μg mL-1). Finally, the analysis by fluorescence microscopy for localization and cellular staining using Vero cells demonstrated that the compounds stained the cytoplasm and the nuclei in a selective way.

Role of Pauli blocking for enhancement of saturable absorption in MoS2/PEDOT:PSS nanocomposite films

We have effectively shown a technique for significantly altering the nonlinear saturable absorption (SA) properties of nanocomposite films (NCFs) based on poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) and molybdenum disulfide (MoS2) by regulating MoS2 concentration and input pulse energy of the laser. The NCFs are made using the straightforward drop-cast process on a glass substrate with varying quantities of MoS2. The produced NCFs’ refractive index (n) and extinction coefficient (k) values are determined using the Kramers–Kronig equations. Nonlinear studies show that the optical nonlinearity of pure PEDOT:PSS changes when mixed with MoS2. The Pauli blocking has been observed in MoS2/PEDOT:PSS NCFs. This leads to enhanced SA in NCF. The open-aperture Z-scan approach is used for the nonlinear optical research, and a nanosecond pulsed laser with a wavelength of 532 nm is used for the excitation. The findings obtained show the NCFs’ strong SA qualities.

A novel application of synthesised based squarylium dyes on nylon 6, and silk woven fabrics

Abstract Squarylium dyes were synthesized and characterized by different spectrometric techniques using FT-IR, UV-visible and GC–MS, the dyes gave molar extinction coefficient values greater than 5.2812 × 105 L mol−1 cm−1. Their fastness properties in respect to wash, light, perspiration and hot pressing on nylon 6, and silk fabrics were analyzed, effects of time, temperature, carrier concentration and pH was also investigated and reported. The dyed fabrics showed good to very good wash, light fastness, and perspiration good to very good hot pressing on nylon 6 and good to very good on silk fabric, respectively. The dye-bath exhaustion was found to be between 76 and 92% on nylon 6 and 57 and 85% on silk, respectively. The percentage exhaustion on nylon 6 was found to be very good to excellent but on silk it was found to be good to very good. These studies showed that squarylium dyes can be applied to nylon 6 and silk fabrics, but better performance was found on nylon 6 than silk fabric.

Numerical simulation of duct flow in the presence of participating media radiation with total energy based entropic lattice Boltzmann method

Consideration of the effect of participating media radiation becomes essential for industrial systems due to the increasing use of high temperature materials. Participating media radiation is present in these systems with all other modes of heat transfer. The Lattice Boltzmann method is emerging as a powerful technique to handle the heat flow problems involving participating media radiation. This work proposes a specific method for applying the total energy based formulation of the double population entropic Lattice Boltzmann method for flow problems with participating media. All flow variables are calculated by means of an integrated Lattice Boltzmann solver for mass, momentum, energy and radiative energy propagation. The formulation based on the total energy is modified to account for the effects of the participating media. The modification is verified by the Chapman–Enskog procedure. Reference cases are adopted for validation of the model and formulation. Detailed analyses of the physics involving the flow structure and radiation properties as well as the implementation details of the computation procedure are given. The interactions of the flow field with the participating media in duct flow are investigated varying Reynolds number, single scattering albedo and extinction coefficient values.