Optical Studies Research Articles

Excitation mechanisms of Cii optical permitted lines in ionized nebulae

Carbon is the fourth most abundant element in the universe and its distribution is critical to understanding stellar evolution and nucleosynthesis. In optical studies of ionized nebulae, the only way to determine the C/H abundance is by using faint recombination lines (RLs). However, these lines give systematically higher abundances than their collisionally excited counterparts, observable at ultraviolet (UV) wavelengths. Therefore, a proper understanding of the excitation mechanisms of the faint permitted lines is crucial for addressing this long-standing abundance discrepancy (AD) problem. In this study, we investigate the excitation mechanisms of lines $ 3920, 4267, 5342, 6151, 6462, 7231, 7236, 7237, and 9903. We use the DEep Spectra of Ionized REgions Database (DESIRED) that contains spectra of regions, planetary nebulae and other objects to analyze the fluorescence contributions to these lines and the accuracy of the atomic recombination data used to model the $ ion. We find that 5342, 6151, 6462, and 9903 arise exclusively from recombinations with no fluorescent contributions. In addition, the recombination theory for these lines is consistent with the observations. Our findings show that the AD problem for $ is not due to fluorescence in the widely used lines or errors in their atomic parameters, but to other phenomena such as temperature variations or chemical inhomogeneities. On the other hand 3920, 6578, 7231, 7236, 7237 have important fluorescent contributions, which are inadvisable for tracing the $ abundances. We also discuss the effects of possible inconsistencies in the atomic effective recombination coefficients of 7231, 7236, and 7237.

Structural and Optical Studies on Cr-Doped ZnS Nanoparticles Prepared by Flat Co-precipitation Method

Structural and Optical Studies on Cr-Doped ZnS Nanoparticles Prepared by Flat Co-precipitation Method

Cadmium Yellow Pigments in Oil Paintings: Optical Degradation Studies Utilizing 3D Fluorescence Mapping Supported by Raman Spectroscopy and Colorimetry

The degradation of cadmium yellow in paintings is influenced by various factors, primarily environmental conditions and light exposure. Applying a thin protective layer of linseed oil on the surface could help mitigate these processes. Linseed oil, being a natural material, acts as a barrier against harmful atmospheric agents like moisture and oxygen, which contribute to the degradation of pigments including cadmium yellow. Additionally, linseed oil reduces direct light exposure, thereby lowering the risk of fading and color alteration. In this study, we explored the degradation of cadmium pigments mixed with oil and applied on canvas. We elucidated how the use of a binder prevents the direct oxidation of the pigment, inducing artificial degradation by irradiating samples with UVA (365 nm) and UVC (250 nm) sources. By employing various spectroscopic techniques such as three-dimensional fluorescence mapping (PLE) and Raman, along with colorimetric analysis, we gained a comprehensive understanding of the degradation process, particularly when linseed oil serves as a protective layer.

Identifying Current Collectors that Enable Light-Battery Interactions.

In recent years, there has been an increased focus on studying light-battery interactions in the context of operando optical studies and integrated photoelectrochemical energy harvesting. However, there has been little insight into identifying suitable "light-accepting" current collectors for this class of batteries. In this study, fluorine-doped tin oxide, indium-tin oxide, and silver nanowire-graphene films are analyzed along with carbon paper, carbon nanotube paper, and stainless-steel mesh as current collectors for optical batteries. They are categorized into two classes - transmissive and non-transmissive, based on the orientation of the light-electrode interaction. Various methods to prepare the electrode are highlighted, including drop casting and the fabrication of free-standing electrodes. The optical and electrical properties of these current collectors as well as their electrochemical stability are measured using linear sweep voltammetry against zinc and lithium anodes. Finally, the rate performance and long-term cycling stability of lithium manganese oxide (LiMn2O4) cathodes are measured against lithium anodes with these current collectors and their performance is compared. These results show which current collector to choose depends on the application and cell chemistry. These guidelines will assist in the design of future optical cells for in-situ measurements and photoelectrochemical energy storage.

Structural, optical, and morphological study of iron-nickel co-doped calcium hydroxide nanoparticles

Structural, optical, and morphological study of iron-nickel co-doped calcium hydroxide nanoparticles

Spatial photoluminescence and lifetime mappings of quasi-2D perovskites coupled with a dielectric metasurface.

Light-matter interaction between quantum emitters and optical cavities plays a vital role in fundamental quantum photonics and the development of optoelectronics. Resonant metasurfaces are proven to be an efficient platform for tailoring the spontaneous emission (SE) of the emitters. In this work, we study the interplay between quasi-2D perovskites and dielectric TiO2 metasurfaces. The metasurface, functioning as an open cavity, enhances electric fields near its plane, thereby influencing the emissions of the perovskite. This is verified through angle-resolved photoluminescence (PL) studies. We also conducted reflectivity measurements and numerical simulations to validate the coupling between the quasi-2D perovskites and photonic modes. Notably, our work introduces a spatial mapping approach to study Purcell enhancement. Using fluorescence lifetime imaging microscopy (FLIM), we directly link the PL and lifetimes of the quasi-2D perovskites in spatial distribution when positioned on the metasurface. This correlation provides unprecedented insights into emitter distribution and emitter-resonator interactions. The methodology opens a new (to the best of our knowledge) approach for studies in quantum optics, optoelectronics, and medical imaging by enabling spatial mapping of both PL intensity and lifetime, differentiating between uncoupled quantum emitters and those coupled with different types of resonators.

Charge transport mechanism and mechanical properties of rubidium cerium metaphosphate glasses

Cerium-doped glasses usually contain a mixture of Ce3+ and Ce4+ species, with the trivalent state being dominant. Quantitative determination of the redox ratio is complicated by the narrow energy gap between both states, leading to spectral overlap in optical absorption studies, and strong beam sensitivity in other techniques. However, it also indicates a way to induce electric conduction through electron hopping, with the additional benefit of visual transparency. Here, cerium phosphate glasses are reported in which the local optical basicity is varied through substitution of cerium by highly polarizable rubidium ions. This is done in order to control the Ce3+/ Ce4+ ratio. Electrical impedance spectroscopy is considered as an alternative means to assess the redox ratio by exploring the extent of polaron conduction. Complementary Raman and 31P MAS NMR spectroscopic studies provide structural insight on the process of mixed electronic and ionic charge transport. Meanwhile, a monotonic decrease in the elastic modulus and an abnormal change in Poisson's ratio when varying the composition corroborate structural interpretations.

Structural, electrical, optical, and DFT studies of phenothiazine-based D–π–A frameworks for dye-sensitized solar cell applications

Structural, electrical, optical, and DFT studies of phenothiazine-based D–π–A frameworks for dye-sensitized solar cell applications

Influence of the DEA Concentration on Structural and Optical Properties of Nanodot PbS Thin Films Growth by Chemical Solution Deposition: Unveiling Dual Optical Absorption Edges

The present paper presents a straightforward method for producing thin film layers of sulfide quantum dots (PbS-QDs) on a glass substrate using chemical solution deposition (CSD) assisted by dipcoating technique. The deposited PbS-QDs films were subjected to a comprehensive analysis using atomic force microscopy (AFM), energy dispersive X-ray (EDX) scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis–IR absorption, and photoluminescence spectroscopic (PL) techniques to investigate the effects of varying concentrations of diethanol amine (DEA) on their morphology, crystal structure, elemental composition, light absorption, and emission characteristics. The spherical shape of the PbS-QDs was confirmed by AFM and SEM images with average sizes around 100 and 50 nm, respectively. The energy dispersive X-ray (EDX) analysis provides evidence the existence of Pb and S elements within the PbS matrix. X-ray diffraction (XRD) results validate that the deposited films exhibit high crystallinity, with a preferential orientation along the (111) plane and a face-centered cubic lattice structure of PbS. The crystallite size of PbS is measured to be 46.6 nm. Based on the optical absorption measurements, we have determined the size range of PbS nanocrystals to be between 4.3 and 11.5 nm. The optical studies reveal the presence of two optical absorption edges within the visible and infrared spectrum, two direct band gap energy, two cut-off wavelengths, two confinement energy, two Urbach energy tail, and dual emission peaks of PbS-QDs at room temperature. The analysis reveals the presence of two distinct band gap energies, one in the visible range (1.3–2.28 eV) and the other in the infrared range (0.65–0.88 eV), which can be attributed to the formation of two distinct sizes of quantum dots situated in two different layers. The first layer, deposited directly on the glass substrate, comprises quantum dots with an average size of approximately 5.2 nm, while the second layer contains quantum dots with an average size of about 9.5 nm. This ability to tune the band gap of PbS in the visible range up to the IR band (0.65–2.28 eV) is a critical feature that holds the potential for the development of innovative optoelectronic devices.

Structural, band profiles and optical reflectivity studies of ALi2B (A = Cu, Ag; B = Ge, Sn, Pb) compounds

Abstract The subject of given project is to highlight the basic elastic, electronic and optical reflectivity of ALi2B (A = Cu, Ag; B = Ge, Sn, Pb). For the calculation of these properties, we used the full potential linearized augmented plane wave (FP-LAPW) procedures carry through Wien2k package. Specifically, the Perdew, Burke and Ernzerhof’s generalized gradient approximation (PBE-GGA) and Wu and Cohen generalized gradient approximation (WC-GGA) have been used. The obtained results fit well with existing experimental data. Different elastic parameters, such as constant of elasticity, elastic moduli, Poisson’s ratio, anisotropy factor and Cauchy pressure, are calculated for the first time for the compounds. The elastic properties clearly summarized the compound’s elastically stability and brittleness in both zinc blend phase. The band structure results for ALi2B shows that the compounds are metallic having overlapping bands across the electron chemical potential. The valance band highest energy state is composed from combination of Cu-d and Sn-p state, disclosed through these compound’s total (DOS) plots, whereas the conduction band primarily constitution is from Li-p, Sn-s Cu-s and Sn-p states. The intraband transitions play vital rule in the description of the optical reflectivity of the ALi2B compounds.

Syntheses, crystal structures, and physical properties of non-centrosymmetric MgIn2Te4 and MnIn2Te4

In this study, we prepared two ternary tellurides, MgIn2Te4 and MnIn2Te4 (single crystals and bulk polycrystalline phases), by directly fusing the elements at high temperatures using the sealed tube synthesis method. Single crystal X-ray diffraction studies confirmed the non-centrosymmetric tetragonal structures (space group: I4‾ 2m) of the MgIn2Te4 and MnIn2Te4 phases with two formula units (Z = 2). Interestingly, the refined unit cell lengths of a = b = 6.2149(5) Å and c = 12.4240(19) Å for the MgIn2Te4 are slightly longer than those of the MnIn2Te4 structure (a = b = 6.1901(3) Å and c = 12.3877(7) Å). The asymmetric unit of these two MIn2Te4 (M = Mg and Mn) isostructural compounds contains three crystallographically independent sites: two disordered metal sites (M1/In1, M2/In2) and one Te1 site. Each metal atom in these structures is tetrahedrally coordinated with four Te1 atoms. Optical absorption studies for polycrystalline MgIn2Te4 and MnIn2Te4 samples showed bandgaps of 1.1(2) eV and 0.9(2) eV, respectively, consistent with these powders' black color. Seebeck studies confirm that holes are the majority of charge carriers for the MgIn2Te4 sample. The thermal conductivity (ktot) studies of the samples reveal ultralow values at 773 K: 0.37 Wm−1K−1 for the MgIn2Te4 and 0.44 Wm−1K−1 for the MnIn2Te4. Magnetic studies on the polycrystalline MnIn2Te4 show a paramagnetic behavior with a magnetic moment of 5.73 μB. Our theoretical studies indicate the possibility of achieving a high thermoelectric figure of merit (zT > 1.5) by optimizing the hole concentration in the MgIn2Te4 sample.

Wet synthesis of magnetically retrievable Mn/Nd co-doped cobalt ferrites for visible light-driven photocatalytic annihilation of azo dye

In this study, a surfactant assisted wet-chemical method was used to synthesize manganese and neodymium co-doped cobalt ferrite [Co1-xFe2-y O4 (x = Mn, y = Nd)]. The co-doping strategy was adopted to enhance the magnetic properties, tune the band gap, and hamper charge–recombination in the spinel ferrite during the photocatalytic application. Different dopant concentrations, namely Mn = Nd = 1.1 %, 2.2 %, 3.3 %, and, 4.4 %, were used to synthesize MNCF-1, MNCF-2, MNCF-3, and MNCF-4 samples, respectively. The pristine (CF) and co-doped samples (MNCF) were characterized via TGA, PXRD, Raman, FTIR, and UV/Vis techniques to examine the impact of co-doping on the various physicochemical and thermal properties. The optical study proposed the MNCF-4 sample with a band gap value of 2.88 eV as most suitable for visible-light harvesting. A dielectric study showed that co-doped ferrite with a higher dopant concentration (MNCF-4) exhibits boosted AC conductivity and substantially decreased leakage current as compared to the bare and co-doped samples. As the concentrations of the co-dopants increase, the coercivity field (Hc) decreases while the remanent magnetization (Mr) and saturation magnetization (Ms) increase. The MNCF-4 material exhibited the highest magnetic properties, ensuring its full and quick magnetic recovery at the completion of the photocatalytic process. In the context of photocatalytic applications, it was observed that the MNCF-4 catalyst exhibited a mineralization rate constant value of 0.016 min−1 for 92.5 % crystal violet (CV) dye. To mitigate the impact of dye sensitization, the photocatalytic efficiency of MNCF-4 material was assessed by using phenol as a representative colourless organic pollutant. The enhanced magnetic properties of the MNCF-4 catalyst enable its complete magnetic recovery and 90.2 % retention of the photocatalytic activities after five reusability tests.

CHARACTERIZATION AND OPTICAL STUDIES OF ION BEAM-IRRADIATED CA/PANI COMPOSITE MATERIALS

In the present research, cellulose acetate (CA) and polyaniline (PANI) were combined to form CA/PANI films using the solution-casting method. This research aims to provide novel optical behavior for irradiated flexible CA/PANI sheets to be utilized in high-performing optical devices. The Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM) were employed to effectively produce the CA/PANI samples. The argon fluence of [Formula: see text], [Formula: see text], and [Formula: see text][Formula: see text]ions/cm2 have been added to these films. The FTIR and XRD measurements showed that the ion treatment of CA/PANI films altered their functions and crystalline compositions. This indicates that the CA/PANI films were successfully prepared. The optical properties were measured using the UV–Vis technique in a wavelength of 200–1150[Formula: see text]nm. The Tauc relationship was used to estimate the band gap and Urbach energies of both bombarded and untreated films. In response to [Formula: see text], [Formula: see text], and [Formula: see text][Formula: see text]ions/cm2, CA/PANI exhibits a drop in band gap from 4.92[Formula: see text]eV to 4.45, 4.31, and 4.20[Formula: see text]eV, respectively. According to these results, the optical performance of the irradiated CA/PANI composite films was modified to be used in optoelectronics.

Luminescence features of Dy3+-doped B2O3 and B2O3-P2O5 hosts for optical devices: the linear and non-linear optical studies

Luminescence features of Dy3+-doped B2O3 and B2O3-P2O5 hosts for optical devices: the linear and non-linear optical studies

Structural, optical and theoretical studies of 2,4-dichlorobenzoic acid benzamide in nonlinear optical applications using Z-scan technique

New organic 2,4-dichlorobenzoic acid benzamide co-crystal (DCBB) was successfully grown using slow evaporation solution growth technique. The formation of new DCBBco-crystals was taken and their structure and crystallinity were analyzed by single crystal and powder X-ray diffraction analyses. It shows that DCBB material in monoclinic structure with centrosymmetric space group of P21/c. The different vibrations, chemical bonding and chemical configuration of the co-crystal was studied through FTIR, Raman and 1H NMR spectroscopy. Optical transmittance is the basic requirement for the nonlinear optical application with a lower cutoff wavelength of about 320 nm as well as optical band gap value Eg is 3.84 eV. Photoluminescence spectrum showing two emission peaks of 403 and 550 nm by means of an excitation wavelength of 290 nm. The compound's thermal stability was up to 125 °C was analyzed by the thermal analysis. Vickers's micro hardness test was used for evaluating mechanical properties of DCBB, and the results showed that the material was classified as soft category (n = 2.54). Nonlinear optical characteristics of the sample under pulsed laser stimulation by Q-switched Nd:YAG laser with 532 nm wavelength. The presence of reverse saturable absorption peak exhibits 2-photon absorption process was confirmed by varying its intensity shows saturation intensity IS), nonlinear absorption coefficient (β) under pulse laser excitation. The optical limiting threshold determined by three different intensities were found to be 3.02×1012 (W/m2), 2.85×1012 (W/m2) and 1.44×1012 (W/m2) respectively. Theoretical investigations like density functional theory using B3LYP to calculate as well as determining non-linear optical characteristics of the DCBB complex.

Air-Stable and Eco-Friendly Symmetrical Imine with Thiadiazole Moieties in Neutral and Protonated form for Perovskite Photovoltaics.

This paper proposes molecular and supramolecular concepts for potential application in perovskite solar cells. New air-stable symmetrical imine, with thiadiazole moieties PPL2: (5E,6E)-N2,N5-bis(4-(diphenylamino)benzylidene)-1,3,4-thiadiazole-2,5-diamine), as a hole-transporting material was synthesised in a single-step reaction, starting with commercially available and relatively inexpensive reagents, resulting in a reduction in the cost of the final product compared to Spiro-OMeTAD. Moreover, camphorsulfonic acid (CSA) in both enantiomeric forms was used to change the HOMO-LUMO levels and electric properties of the investigated imine-forming complexes. Electric, optical, thermal, and structural studies of the imine and its complexes with CSA were carried out to characterise the new material. Imine and imine/CSA complexes were also characterised in depth by the proton Nuclear Magnetic Resonance 1H NMR method. The position of nitrogen in the thidiazole ring influences the basicity of donor centres, which results in protonation in the imine bond. Simple devices of ITO/imine (with or without CSA(-) or CSA(+))/Ag/ITO architecture were constructed, and a thermographic camera was used to find the defects in the created devices. Electric behaviour was also studied to demonstrate conductivity properties under the forward current. Finally, the electrical properties of imine and its protonated form with CSA were compared with Spiro-OMeTAD. In general, the analysis of thermal images showed a very similar response of the samples to the applied potential in terms of the homogeneity of the formed organic layer. The TGA analysis showed that the investigated imine exhibits good thermal stability in air and argon atmospheres.

[Effects of Susac syndrome on the central vascular structure of the retina-An optical coherence tomography angiography study].

Susac syndrome (SS)describes an endotheliopathy of vessels in the central nervous system. Retinal involvement plays acentral role in the manifestation of the disease. This case-control study investigated the macular microvasculature in patients with chronic SS compared to controls using optical coherence tomography angiography (OCTA). 12eyes of 12patients with SS were compared with age-matched healthy control subjects with regard to their OCT angiographic parameters. The flow density (FD) of different macular layers, foveal avascular zone (FAZ) parameters and central retinal thickness and volume values were compared between the two groups. The FD of the choriocapillaris was reduced in Susac patients compared to healthy controls. The FD values of the superficial and deep capillary plexus of the inner retina, parameters of the FAZ as well as central retinal thickness and volume showed no significant differences between the two groups. Treated chronic SS does not appear to significantly affect the vascular and structural composition of the central inner retina; however, differences in the choriocapillaris indicate changes in deeper, highly vascularized capillary layers.

Optical and magnetic studies of Co0.7Zn0.3Fe2O4 spinel ferrites with Dy3+ substituted for the application of sensors prepared through sol–gel process

Optical and magnetic studies of Co0.7Zn0.3Fe2O4 spinel ferrites with Dy3+ substituted for the application of sensors prepared through sol–gel process

Curcumin analogue: Synthesis, DFT and nonlinear optical studies

The synthesis of a new curcumin analogue dye via 3-chloro-2,4-pentanedion condensing with an aromatic aldehyde is considered. Following that, the synthesized compound is diagnosed utilizing spectroscopic methods, including FTIR, mass, 1H NMR, and 13CNMR. The curcumin analogue geometric optimization and theoretical studies are conducted on thermodynamic properties using DFT. The B3LYP techniques, which are hybrid functional with a 6–311+G(d) as the basis set, are adopted to compute the HOMO, LUMO, and Mullikan atom charges of the studied compound. The curcumin analogue dye nonlinear optical (NLO) properties are examined under excitation with a 473 nm, low power, cw and TEM00 mode laser beam. The index of nonlinear refraction (INLR) and coefficient of nonlinear absorption (CNLA) are estimated using diffraction patterns for the former and Z-scan for the latter. The INLR reaches a value as high as 6.86×10−11 m2/W, while the CNLA reaches 2.23×10−3 cm/W. All-optical switching (AOS) is tested in the novel curcumin analogue dye using two methods: static AOS and dynamic AOS.

Vericiguat suppresses ventricular tachyarrhythmias inducibility in a rabbit myocardial infarction model.

The VICTORIA trial demonstrated a significant decrease in cardiovascular events through vericiguat therapy. This study aimed to assess the potential mechanisms responsible for the reduction of cardiovascular events with vericiguat therapy in a rabbit model of myocardial infarction (MI). A chronic MI rabbit model was created through coronary artery ligation. Following 4 weeks, the hearts were harvested and Langendorff perfused. Subsequently, electrophysiological examinations and dual voltage-calcium optical mapping studies were conducted at baseline and after administration of vericiguat at a dose of 5 μmol/L. Acute vericiguat therapy demonstrated a significant reduction in premature ventricular beat burden and effectively suppressed ventricular arrhythmic inducibility. The electrophysiological influences of vericiguat therapy included an increased ventricular effective refractory period, prolonged action potential duration, and accelerated intracellular calcium (Cai) homeostasis, leading to the suppression of action potential and Cai alternans. The pacing-induced ventricular arrhythmias exhibited a reentrant pattern, attributed to fixed or functional conduction block in the peri-infarct zone. Vericiguat therapy effectively mitigated the formation of cardiac alternans as well as the development of reentrant impulses, providing additional anti-arrhythmic benefits. In the MI rabbit model, vericiguat therapy demonstrates anti-ventricular arrhythmia effects. The vericiguat therapy reduces ventricular ectopic beats, inhibiting the initiation of ventricular arrhythmias. Furthermore, the therapy successfully suppresses cardiac alternans, preventing conduction block and, consequently, the formation of reentry circuits.