Optical Parameters Absorption Research Articles

Tailoring optical and photocatalytic properties of sulfur-doped boron nitride quantum dots via ligand functionalization

Boron nitride quantum dots (BNQDs) have emerged as promising photocatalysts due to their excellent physicochemical properties. This study investigates strategies to enhance the photocatalytic performance of BNQDs through sulfur-doping (S-BNQDs) and edge-functionalization with ligands (urea, thiourea, p-phenyl-enediamine (PPD)). To analyze the geometry, electronic structure, optical absorption, charge transfer, and photocatalytic parameters of pristine and functionalized S-BNQDs, we performed density functional theory calculations. The results showed that S-doping and ligand functionalization tune the bandgap, band energies, and introduce mid-gap states to facilitate light absorption, charge separation, and optimized energetics for photocatalytic redox reactions. Notably, the PPD ligand induced the most substantial bandgap narrowing and absorption edge red-shift by over 1 electron volt (eV) compared to pristine S-BNQD, significantly expanding light harvesting. Additionally, urea and PPD functionalization increased the charge transfer length by up to 2.5 times, effectively reducing recombination. On the other hand, thiourea functionalization yielded the most favorable electron injection energetics. The energy conversion efficiency followed the order: PPD (15.0%) > thiourea (12.0%) > urea (11.0%) > pristine (10.0%). Moreover, urea functionalization maximized the first-order hyperpolarizability, enhancing light absorption. These findings provide valuable insights into tailoring S-BNQDs through strategic doping and functionalization to develop highly efficient, customized photocatalysts for sustainable applications.

Structural Investigation and Optical Properties of Dysprosium (Dy3+) Ions Doped Oxyfluoro Antimony Borate Glasses for Photonics Applications.

Dysprosium oxide-doped glasses with a composition of 60B2O3-10Sb2O3-10Al2O3-10NaF-(10-x) LiF-xDy2O3 (x = 0.1,0.5, 1.0,1.5,2.0,2.5 mol%) were prepared using a conventional melt-quenching technique. The glasses were characterized through various analytical investigations, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, refractive index, density, optical absorption, excitation, photoluminescence (PL) studies, decay measurements and radiation shielding parameters. The XRD and FT-IR confirms the glassy nature and functional groups present in the titled glass. The absorption spectra were used to determine the oscillator strength of the Dy3+ absorption transitions as well as the bond created with the O-2 ion in the titled glass network. The degree of the suitability of developed glasses for lasing applications was demonstrated by radiative parameters determined using Judd-Ofelt theory. In the prepared glass samples, the optical bandgap measurements indicate the presence of non-bridging oxygen (NBOs), localization of charges and donor centers in the titled glasses. Due to the de-excitation of 4F9/2 to the corresponding 6H15/2,6H13/2 and 6H11/2 states, the PL emission spectrum shows two main strong emissions at blue(480nm), yellow (575nm) and one less emission at red (663nm). The CIE coordinates determined using PL emission spectra reveal the coordinates that are falling within the white light region. Various shielding parameters such as mass attenuation coefficient, mean free path, effective atomic number were estimated to understand the radiative shielding nature of the titled glasses. Within the addition of Dy2O3, it was found that the shielding parameters values of the titled glass samples are increasing. The Mass Attenuation Coefficient, Half Value Layer and Mean Free Path of the as prepared glasses has been compared with different types of concretes to understand the shielding effectiveness of prepared glass.

A Differential Diffusion Theory for Participating Media

AbstractWe present a novel approach to differentiable rendering for participating media, addressing the challenge of computing scene parameter derivatives. While existing methods focus on derivative computation within volumetric path tracing, they fail to significantly improve computational performance due to the expensive computation of multiply‐scattered light. To overcome this limitation, we propose a differential diffusion theory inspired by the classical diffusion equation. Our theory enables real‐time computation of arbitrary derivatives such as optical absorption, scattering coefficients, and anisotropic parameters of phase functions. By solving derivatives through the differential form of the diffusion equation, our approach achieves remarkable speed gains compared to Monte Carlo methods. This marks the first differentiable rendering framework to compute scene parameter derivatives based on diffusion approximation. Additionally, we derive the discrete form of diffusion equation derivatives, facilitating efficient numerical solutions. Our experimental results using synthetic and realistic images demonstrate the accurate and efficient estimation of arbitrary scene parameter derivatives. Our work represents a significant advancement in differentiable rendering for participating media, offering a practical and efficient solution to compute derivatives while addressing the limitations of existing approaches.

Tunable emission glass ceramic nanocomposites via devitrification of glassy Na2O-GeO2-MnO2 for optoelectronic and optical limiting applications

Manganese (IV) ion has been deemed a functional non-rare-Earth activator for the generation of red emissions, while the oxide and fluoride hosts that provide suitable sites for Mn4+ have to be prepared with usually rigorous control of reaction conditions, including redox equilibrium and temperature. In this study, the parent glass with 20Na2O- 80GeO2- 0.1 MnO2, in mol% composition is prepared via conventional melt-quenching, and the devitrification of the glass is induced by thermal treatment. The capability of appropriate thermal treatment to transform glasses into glass-ceramic nanocomposites (GCNs) with crystallites smaller than 21 nm was confirmed by XRD measurements. An enhancement in the optical characteristic of the GCNs is induced owing to the modifications in the microstructure. Tauc’s and ASF models were used to calculate the direct allowed transition energy. Localized states in the forbidden region cause the decrease in the glass ceramic’s bandgap (E g opt), as illustrated by the Urbach energy (Eu) values. Optical absorption parameters and the relation between transition energy and refractive index (n) were investigated. The increase in heat treatment temperature induces an improvement in the nonlinear (X(3)) susceptibility and (n(2)) refractive parameters. The synthetic method demonstrated here for Na2Ge4O9:Mn4 + might be extended for the synthesis of other phosphors-containing activators with a high oxidation state. Moreover, Optical Cut-Off characteristics (OCC) revealed that the sample reduces the light transmission intensity by higher heat treatment temperature. The results suggest that 540° heat-treated samples are encouraging materials in a variety of optoelectronics applications, and mainly optical apparatus.

Fabrication of CNTs-reinforced poly(vinyl alcohol) nanocomposite film with tailored structural, surface chemical and optical properties

Purpose This study aims to fabricate multiwalled carbon nanotubes (MWCNTs)-mediated polyvinyl alcohol (PVA) composite films using the solution casting approach. Design/methodology/approach The prepared films were evaluated for diverse structural, surface, optical and electrical attributes using advanced analytical techniques, i.e. electron microscopy for surface morphology, Fourier transform infrared spectroscopy for tracing chemical functionalities, x-ray diffraction (XRD) for crystal patterns, water contact angle (WCA) analysis for surface wettability and UV visible spectroscopy for optical absorption parameters. The specimens were also investigated for certain rheological, mechanical and electrical properties, where applicable. Findings The surface morphology results expressed a better dispersion of MWCNTs in the resultant PVA-based nanocomposite film. The XRD analysis exhibited that the nanocomposite film was crystalline. The surface wettability analysis indicated that with the inclusion of MWCNTs, the WCA of the resultant nanocomposite film improved to 89.4° from 44° with the pristine PVA film. The MWCNTs (1.00%, w/w) incorporated PVA-based film exhibited a tensile strength of 54.0 MPa as compared to that of native PVA as 25.3 MPa film. There observed a decreased bandgap (from 5.25 to 5.14 eV) on incorporating the MWCNTs in the PVA-based nanocomposite film. Practical implications The MWCNTs’ inclusion in the PVA matrix could enhance the AC conductivity of the resultant nanocomposite film. The prepared nanocomposite film might be useful in designing certain optoelectronic devices. Originality/value The results demonstrated the successful MWCNTs mediation in the PVA-based composite films expressed good intercalation of the precursors; this resulted in decreased bandgap, usually, desirable for optoelectronic applications.

Microstructure, electronic transitions and UV transparency of K2O–B2O3–Sm2O3 glass via PbO additives

Samarium-doped borate glass is widely used in solid-state devices due to their suitable refractive index and appealing spectral characteristics. Here, we used the melt quenching technique and characterized the microstructure, optical absorption, electronic transitions and non-linear optical parameters of K2O-borate glass doped with a constant amount of Sm2O3 (1.8 mol %) and different amounts of PbO (0, 5, 10, 15 and 20 mol %), primarily using Fourier-transform Infrared (FTIR) and optical absorbance. FTIR results confirmed the strong influence of PbO on the glass internal structure. Further, inspecting the optical absorption, we found the following results. The optical absorption bands at 401, 475, 935, 1073, 1226, 1369, 1468, 1528, and 1942 nm are recognized to Sm3+ cation's electronic transitions from 6H5/2 (ground state) to 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6H13/2 states respectively. Furthermore, for the PbO-free glass sample, an absorption band we observed at ∼220 nm in the UVC-domain. Moreover, this PbO-free glass sample is transparent in the rest of the UV-regions. A broad absorption band starts to appear with increasing the PbO concentrations in the glass system. The broadening of this band increased with further PbO additions. This band was attributed to Pb2+ cations with 6s2 species that absorb sturdily in the UV-domain. More, the glass sample doped with the highest PbO concentrations (20 mol %) can be considered a UVA transparent material, blocking UVC and UVB. Also, we found the values of Urbach energy, non-linear refractive index, third-order non-linear susceptibility, and refractive index increased for additional PbO contents, which is attributed to the increased disorder in the glass matrix. Furthermore, the results propose that the PbO-free glass sample can be used as UV-transparent material in optical applications. On the other hand, the glass sample that contains the highest PbO concentrations (20 mol %) can be used as a glass filter in some optical applications that permit UVA to pass and block UVC and UVB radiations.

2D Saturable Absorbers for Potential Pulse Generation in the Visible-Wavelength Band

Implementing compact, efficient, and reliable passive pulsed lasers at visible wavelengths is attractive. This paper systematically investigated the thickness-dependent optical absorption characteristics of two-dimensional materials, including graphene, transition-metal dichalcogenides, and dye films at the 532 nm wavelength band, and revealed the effects of thickness on different optical absorption parameters. The results suggested that dye films are more suitable for loss-sensitive pulsed lasers and graphene is more suitable for modulation depth-sensitive pulsed lasers, while transition-metal dichalcogenide samples have intermediate performance. It can provide guidance for the rational selection of saturable absorbers in pulsed all-fiber lasers to optimize the optical pulse performance in the visible-wavelength band.

Optical and radiation absorption properties of bismuth-borate glasses doped with Ce4 +, Nd3 +, and Sm3 +

Three bismuth-borate glasses with the chemical configuration 15Bi2O3-75 H3BO2-10CeO2, 15Bi2O3-75 H3BO2-10Nd2O3, and 15Bi2O3-75 H3BO2-10Sm2O3 and coded as BHB-Ce, BHB-Nd, and BHB-Nd were investigated for their optical and gamma-radiation absorption behaviour. Optical parameters of the glasses such as the molar refractivity, Rm, molar polarizability, αm, reflection loss RL, optical transmission T, metallization criterion M, static dielectric constant εstatic, and optical dielectric constant εoptical were calculated using standard theoretical models. The mass attenuation coefficient μ/ρof the glass samples was estimated by FLUKA simulations and XCOM for discrete photon beams with energies of 0.282, 0.662, 1.33, and 2.51 MeV. The value of Vm was 21.35, 22.61, and 19.60 cm3/mol for BHB-Ce, BHB-Nd, and BHB-Sm, respectively. Also, the highest Rm (16.52 cm3/mol) and αm (6.56 ×10−24 cm3) were obtained for BHB-Ce, while the lowest value was recorded for BHB-Nd (12.035 cm3/mol and 4.78 ×10−24 cm3). Other optical parameters varied with the dopant ion. The photon attenuation coefficient obtained from XCOM calculation and simulations agreed within a 2.90% margin. The μ/ρ varied within the interval 0.0422–0.3086 cm2/g for BHB-Ce, 0.0420–0.3005 cm2/g for BHB-Nd and 0.0420–0.3029 cm2/g for BHB-Sm. The half-value layers (HVLs) vary from 0.3948 cm to 2.8854 cm for BHB-Ce, from 0.3782 cm to 2.7063 cm for BHB-Nd and from 0.3223 cm to 2.3252 cm for BHB-Sm. Based on the values of the photon shielding parameters, the investigated glasses showed better ability to absorb photons compared to conventional shields such as barite concrete, ordinary concrete, and some commercial glass shields. The analysis of the optical and radiation absorption parameters shows that the BHB-glasses are useful in optical and gamma-radiation absorption technologies.

ZnO/CdO translocation in P2O5-TeO2-ZnO ternary glass systems: A reformative enhancement tool for physical, optical, and heavy-charged particles attenuation properties

We report the optical, physical, structural, and heavy charged particle absorption parameters of CdO doped P2O5-TeO2-ZnO ternary glass structures with a nominal composition of 20 P2O5.30TeO2.(50-x)ZnO.xCdO (x = 0, 2, 4, 6, 8, 10 mol. %). Physical as well as optical characteristics of the synthesized glasses are measured using experimental methods. ZnO/CdO translocation is caused an increase in the density of the synthesized samples. Synthesized glasses are reported along with seventeen different bands as a result of deconvolution processes. The structure is formed more tightly and regularly with ZnO/CdO translocation process. As a result of the evaluation of the absorption edge, transmittance of the glass without CdO additive is reported around 338 nm in the 20–30 % transmittance region, the absorption edge of all the glasses doped with CdO is shifted to around 336 nm. According to results, un-doped C0 glass is observed more unstable and far from homogeneous than doped glasses with the largest Urbach energy value (0.1506 eV), while C10 glass is observed as much more stable and uniform when compared to all glasses in this study with a value of 0.1311 eV. Moreover, projected range values of alpha and protons grew as the energy level increased. The shortest lengths that alpha and protons may travel at the same energy levels are reported for the C10 sample, which has the highest CdO contribution as well as the highest glass density. C10 glass sample is reported to have the maximum degree of clarity, making it one of the most important qualifying requirements for shields in medical radiation facilities, where the observation of both the patient and the physical radiation source is crucial. It can be concluded that the investigated ZnO/CdO translocation process may be seen as a beneficial tool for P2O5-TeO2-ZnO ternary glass structures in terms of enhancing optical, physical, and heavy charged particle attenuation properties.

Structural, optoelectronic and thermodynamic characteristic of orthorhombic SnZrCH3(CH=S, Se) compounds: Insights from DFT computations

In this research work, a study on the structural, optoelectronic, and thermodynamics propertiesof the SnZrCH3 (CH = S, Se) compounds is presented. The study is performed by the “full potential linearized augmented plane wave plus local orbitals (FP-(LAPW + lo)) method framed within density functional theory (DFT). To treat with exchange-correlation energy/potential, different approximations; local density approximation (LDA), generalized approximation (GGA) by Wu and Cohen (WC) named as (WC-GGA) are used toestimate structural properties such as lattice constants, bulk moduli,and related results of pressure derivative.Besides that Engel Vosko's approach of GGA named as (EV-GGA) and Becke-Johnson modified form of exchange-correlation potential (mBJ-GGA) is also used to obtain reliable results of the electronic and optical properties. Our calculations of electronic band structures and density of states endorse both compounds of indirect bandgapnature withbandgap energy 1.054 eV and 0.531 eV for SnZrS3 and SnZrSe3, respectively at the level ofmBJ-GGA. Our calculations of the optical absorption parameters show the highest values of absorption coefficients in the ultraviolet (UV) region, attributed to localized Zirconium states lying in the lower region of the conduction band. Hence, our findings show that both SnZrS3 and SnZrSe3 compounds are potential candidates for photovoltaic applications.Moreover, the pressure effects on the lattice constants, heat capacities, thermal expansion coefficients, entropy, and Debye temperature are also explored using the quasi-harmonic Debye model.

Enhancing the optical absorption, conductivity, and nonlinear parameters of PVOH films by Bi-doping

New polymeric nanocomposite films of PVOH (polyvinyl alcohol) embedded with Bi-nanoparticles have been described by scanning electron microscopy and x-ray diffractometer. From UV-visible spectroscopy, the absorption edge shifts to the higher wavelengths direction (redshift). Tauc’s model for optical bandgap transitions demonstrates that the direct and indirect values are reduced with the increase of Bi percentage in the PVOH matrix. In contrast, Urbach energy (tail bandwidth), extinction coefficient, refractive index, and optical conductivity are increased. These indicate the rise of the charge transfer among the Bi nanoparticles and the macromolecules of the matrix. Using Wemple–Di Domenico model for single-oscillator, we calculated the nonlinear optical refractive index and susceptibility. The optical limiting characteristic has been tested via a green laser source of wavelength 533 nm. The present results offer new materials for optical Cut-Off and nonlinear optical applications.

Ytterbium (III) oxide reinforced novel TeO2–B2O3–V2O5 glass system: Synthesis and optical, structural, physical and thermal properties

Different samples of xTeO2.(25-y)B2O3.zV2O5.yYb2O3 (or TBVY) new glass material were synthesized by the classical melt-quenching method. Structural, optical, physical, and thermal analyses of the synthesized glasses were performed in addition to Monte Carlo simulation to test radiation shielding properties. The results showed that increasing ratios of Yb2O3 (y = 0.0, 0.5, 1.0, and 1.5 mol%) produced monotonic density values of the synthesized glasses ranging from 4.70058 g cm−3 to 5.01038 g cm−3. XRD and FTIR analyses were used to confirm the glass structure of all samples. Optical transmittance and absorption parameters varied almost monotonically with increasing ratios of Yb2O3 indicating the ability to predict and control these properties using Yb2O3 additive. Furthermore, simulated radiation interaction parameters, such as attenuation coefficients and half-value layer, exhibited well-behaved dependence on the concentration ratio of the Yb2O3 additive. This approach to glass material synthesis demonstrate the useful synergetic effect of combining structural, optical, and radiation characteristics.

Ta Doping Effect on Structural and Optical Properties of InTe Thin Films.

The objective of this work was to study the influence of Ta doping on the structural, transmittance properties, linear absorption parameter, and nonlinear absorption properties of InTe thin films. The as-deposited samples with different Ta doping concentrations were prepared by a magnetron co-sputtering technique and then annealed in nitrogen atmosphere. Structural investigations by X-ray diffraction revealed the tetragonal structure of InTe samples and that the crystallinity decreases with increasing Ta doping concentration. Further structural analysis by Raman spectra also showed good agreement with X-ray diffraction results. The Ta doping concentration and sample thickness determined by energy-dispersive X-ray spectroscopy and scanning electron microscopy increased as Ta dopant increased. In addition, X-ray photoelectron spectroscopic was carried out to analyze the chemical states of the elements. UV–VIS–NIR transmittance spectra were applied to study the transmittance properties and calculate the linear absorption coefficient. Due to Burstein–Moss effect, the absorption edge moved to shorter wavelengths. Meanwhile, the values of band gap were found to increase from 1.71 ± 0.02 eV to 1.85 ± 0.01 eV with the increase of Ta doping concentration. By performing an open aperture Z-scan technique, we found that all Ta-doped InTe samples exhibited two-photon absorption behaviors. The nonlinear optical absorption parameters, such as modulation depth, two-photon absorption coefficient, and two-photon absorption cross-section, decrease with increasing Ta concentration, whereas the damage threshold increases from 176 ± 0.5 GW/cm2 to 242 ± 0.5 GW/cm2. These novel properties show the potential for applications in traditional optoelectronic devices and optical limiters.

Gaining knowledge on source contribution to aerosol optical absorption properties and organics by receptor modelling

In this source apportionment study, an original approach based on receptor modelling was tested to relate primary and secondary organic aerosol (OA) contributions - estimated from ACSM (Aerosol Chemical Speciation Monitor) measurements - to their emission sources. Moreover, thanks to the coupling of optical and chemical variables as input to the receptor model, information such as the impact of mineral dust to the aerosol absorption in the atmosphere and estimates for the absorption Ångström exponent (α) of the sources were retrieved.An advanced source apportionment study using the Multilinear Engine (ME-2) was performed on data collected during February 2017 in Rome (Italy), in the frame of the CARE (Carbonaceous Aerosol in Rome and Environs) experiment. A complete chemical characterisation (elements, non-refractory components, and carbonaceous components) was carried out, and the aerosol absorption coefficients bap(λ) at 7 wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) were retrieved by an Aethalometer AE33; all these variables (chemical + optical) were used as input to the receptor model. The final constrained solution consisted of nine factors which were assigned to major sources impacting on the investigated site (hereafter sources are referred to as: biomass burning, nitrate and aged aerosol, traffic exhaust, sulphate, mineral dust, marine aerosol, traffic non-exhaust, local source, and polluted marine aerosol), comprising both local urban sources and contributions from long-range transport. The bootstrap analysis supported the goodness of the solution.Total OA concentration from ACSM was apportioned by our receptor model and afterwards compared with HOA (hydrocarbon-like organic aerosol), BBOA (biomass burning-like organic aerosol), and OOA (oxygenated organic aerosol) concentrations obtained as results from an independent source apportionment study previously performed. As an original result of this work, insights on OA contributions were thus retrieved: (1) the contribution of organic aerosol assigned by ME-2 to the traffic exhaust source was fully comparable to HOA assessed by ACSM data analysis; (2) our source apportionment results gave the relevant indication that the OOA apportionment made on ACSM data likely includes a secondary OA contribution due to biomass burning.Other relevant results came from bap apportionment obtained by our multi-variable source apportionment approach: traffic exhaust was the main contributor to aerosol absorption in the atmosphere, but mineral dust contribution was also notable when a not negligible mineral dust transport episode was registered at the measurement site. In addition, source dependent optical absorption parameters (i.e. the absorption Ångström exponent - α - and the mass absorption cross section at different wavelengths) were retrieved without any a-priori assumption.In perspective, our modelling approach paves the way to more powerful source apportionment approaches which have the potential of providing much more insights on aerosol properties and sources.

Ab initio calculations of optoelectronic properties of antimony sulfide nano-thin film for solar cell applications

Antimony sulfide (Sb2S3) micro thin-film have been received great interest as an absorbing layer for solar cell technology. In this study, to explore its further potential, electronic and optical properties of Sb2S3 simulated nano-thin film are investigated by the first-principles approach. To do so, the highly accurate full-potential linearized augmented plane wave (FP-LAPW) method framed within density functional theory (DFT) as implemented in the WIEN2k package is employed. The films are simulated in the [0 0 1] direction using the supercell method with a vacuum along z-direction so that slab and periodic images can be treated independently. From our calculations, indirect band gap energy values of Sb2S3 for various slabs are found to be 0.568, 0.596 and 0.609 eV for 1, 2 and 4 slabs respectively. Moreover, optical properties comprising of real and imaginary parts of the complex dielectric function, absorption coefficient, refractive index are also investigated to understand the optical behavior of the obtained simulated Sb2S3 thin films. From the analysis of their optical properties, it is clearly seen that Sb2S3 thin films have good values for optical absorption parameters in the visible and ultraviolet wavelength range, showing the aptness of antimony sulphide thins films for versatile optoelectronic applications as a base material.

2-(4-Ethoxy phenyl)-4-phenyl quinoline organic phosphor for solution processed blue organic light-emitting diodes.

This paper reports the synthesis and characterization of 2-(4-ethoxyphenyl)-4-phenyl quinoline (OEt-DPQ) organic phosphor using an acid-catalyzed Friedlander reaction and the preparation of blended thin films by molecularly doping OEt-DPQ in poly(methyl methacrylate) (PMMA) at different wt%. The molecular structure of the synthesized phosphor was confirmed by Fourier transform infra-red (FTIR) spectroscopy and nuclear magnetic resonance spectra (NMR). Surface morphology and percent composition of the elements were assessed by scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDAX). The thermal stability and melting point of OEt-DPQ and thin films were probed by thermo-gravimetric analysis (TGA)/differential thermal analysis (DTA) and were found to be 80°C and 113.6°C, respectively. UV-visible optical absorption spectra of OEt-DPQ in the solid state and blended films produced absorption bands in the range 260-340nm, while photoluminescence (PL) spectra of OEt-DPQ in the solid state and blended thin films demonstrated blue emission that was registered at 432nm when excited at 363-369nm. However, solvated OEt-DPQ in chloroform, tetrahydrofuran or dichloromethane showed a blue shift of 31-43nm. Optical absorption and emission parameters such as molar extinction coefficient (ε), energy gap (Eg ), transmittance (T), reflectance (R), refractive index (n), oscillator energy (E0 ) and oscillator strength (f), quantum yield (φf ), oscillator energy (E0 ), dispersion energy (Ed ), Commission Internationale de l'Éclairage (CIE) co-ordinates and energy yield fluorescence (EF ) were calculated to assess the phosphor's suitability as a blue emissive material for opto-electronic applications such as organic light-emitting diodes (OLEDs), flexible displays and solid-state lighting technology.

All-Optical Switching of Two Continuous Waves in Few Layer Bismuthene Based on Spatial Cross-Phase Modulation

Bismuthene, the last and heaviest group-VA elemental two-dimensional material, has received tremendous interests owing to its advantages in electronic-transport, semimetallic bonding, and intrinsic spin-orbit coupling. However, light–bismuthene interaction is relatively less investigated. Herein, sonochemical exfoliation approach had been employed to deliver a successful synthesis of few-layer bismuthene with an average thickness of ∼3 nm and a lateral size of ∼0.2 μm. The corresponding band structure from mono- to sextuple-layer had been therotically calculated and it was found that bismuthene possesses a thickness dependent energy gap from almost zero to 0.55 eV, suggesting that bismuthene may also find unique applications from terahertz, mid-infrared toward infrared regime. The nonlinear optical absorption and refraction parameters had been well characterized by laser Z-scan and spatial phase modulation measurement techniques, respectively. By taking advantage of its strong nonlinear refraction effect,...

Large size crystal growth and structural, thermal, optical and electrical properties of KCl1−xBrx mixed crystals

Large size and high quality KCl1−xBrx mixed crystals [with x = 0.0 (pure KCl), 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0 (pure KBr)] have been grown with suitable raw material proportion by the melt (Czochralski) method using the miscible alkali halides KCl and KBr. The grown crystals have been characterized by determining their density, refractive index, lattice constant, chemical composition, thermal parameters (Debye-Waller factor, Debye temperature and Debye frequency), optical absorption, micro hardness and electrical parameters (dielectric constant, dielectric loss factor, AC, and DC electrical conductivities and AC, and DC activation energies) through X-ray diffraction, optical, mechanical and electrical (both AC and DC at various temperatures in the range 30–150 °C) measurements. Results obtained in the present study indicate that mixing KCl with KBr leads to significant tuning of thermal, optical, mechanical and electrical properties without disturbing the crystal structure. The dielectric constant is found to increase several times due to mixing and KCl0.5Br0.5 crystal has the maximum value.

Improvement of thermal and optical properties of lithium phosphate glasses by adding MgO

Collective characterizations of prepared lithium phosphate glass together with samples containing increasing added MgO contents (0–2 mol%) were carried out by differential thermal analysis (DTA), spectroscopic ellipsometry (SE) and photoluminescence (PL) measurements. From the DTA profile, the glass transition temperature T g and crystallization onset temperature T x are estimated. The thermal stability factor was higher than 100 °C suggesting that this glass exhibits a good thermal stability and consequently is suitable to be a potential candidate for fiber drawing. Furthermore, the variation of the ΔT as function of MgO contents has a minimum at 1 mol% of MgO. The refractive index and extinction coefficient data were obtained by analyzing the experimental spectra of tanΨ and cosΔ measured by SE. The complex dielectric functions (e = e 1 + ιe 2) of the samples were estimated from regression analysis. Some of the optical absorption parameters, such as high-frequency dielectric constant, e ∞, the average values of oscillator strength, S o, wavelength of single oscillator, λ o, plasma frequency, ωp, and relaxation time, τ, have been evaluated. The PL spectra of the MgO-doped glass under 325-nm excitation wavelength were studied. The dependence of PL spectra on doping concentration shows a quenching of the PL intensity for MgO concentration above 1 mol%. The variations of the photoluminescence intensity, thermal stability refractive index and optical constants gave an indication to use the prepared glasses for design of novel functional optical materials with higher optical performance.

Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique

The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV–vis–NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q2), and oscillator strength (f), of the principal optical transitions have also been evaluated.