Spectroscopy Measurements Research Articles

State selective preparation and nondestructive detection of trapped O2.

The ability to prepare molecular ions in selected quantum states enables studies in areas such as chemistry, metrology, spectroscopy, quantum information, and precision measurements. Here, we demonstrate (2 + 1) resonance-enhanced multiphoton ionization (REMPI) of oxygen, both in a molecular beam and in an ion trap. The two-photon transition in the REMPI spectrum is rotationally resolved, allowing ionization from a selected rovibrational state of O2. Fits to this spectrum determine spectroscopic parameters of the O2d1Πg state and resolve a discrepancy in the literature regarding its band origin. The trapped molecular ions are cooled by co-trapped atomic ions. Fluorescence mass spectrometry nondestructively demonstrates the presence of the photoionized O2+. We discuss strategies for maximizing the fraction of ions produced in the ground rovibrational state. For (2 + 1) REMPI through the d1Πg state, we show that the Q(1) transition is preferred for neutral O2 at rotational temperatures below 50K, while the O(3) transition is more suitable at higher temperatures. The combination of state-selective loading and nondestructive detection of trapped molecular ions has applications in optical clocks, tests of fundamental physics, and control of chemical reactions.

Supramolecular Engineering of Vinylene-Linked Covalent Organic Framework - Ruthenium Oxide Hybrids for Highly Active Proton Exchange Membrane Water Electrolysis.

The controlled formation of a functional adlayer at the catalyst-water interface is a highly challenging yet potentially powerful strategy to accelerate proton transfer and deprotonation for ultimately improving the performance of proton-exchange membrane water electrolysis (PEMWE). In this study, the synthesis of robust vinylene-linked covalent organic frameworks (COFs) possessing high proton conductivities is reported, which are subsequently hybridized with ruthenium dioxide yielding high-performance anodic catalysts for the acidic oxygen evolution reaction (OER). In situ spectroscopic measurements corroborated by theoretical calculations reveal that the assembled hydrogen bonds formed between COFs and adsorbed oxo-intermediates effectively orient interfacial water molecules, stabilizing the transition states for intermediate formation of OER. This determines a decrease in the energy barriers of proton transfer and deprotonation, resulting in exceptional acidic OER performance. When integrated into a PEMWE device, the system achieves a record current density of 1.0 A cm-2 at only 1.54 V cell voltage, with a long-term stability exceeding 180 h at industrial-level 200 mA cm-2. The approach relying on the self-assembly of an oriented hydrogen-bonded adlayer highlights the disruptive potential of COFs with customizable structures and multifunctional sites for advancing PEMWE technologies.

Aloin reduces advanced glycation end products, decreases oxidative stress, and enhances structural stability in glycated low-density lipoprotein.

Glycation of proteins has been linked to several cardiovascular diseases, including atherosclerosis and diabetes mellitus. Various natural compounds have been explored for their anti-glycating ability. Aloin is the major anthraquinone glycoside, acquired from the Aloe species. This study focuses on aloin's anti-glycating and anti-oxidative potential on glycated low-density lipoprotein (LDL). Fluorescence studies related to anti-glycation showed that aloin significantly reduced the formation of fluorescent advanced glycation end-products (AGEs), hydrophobic environment, and fibrillar aggregates in glycated LDL. A decrease in oxidative stress markers was also seen in glycated LDL in the presence of aloin. Circular dichroism spectra depicted the positive role aloin played in restoring the secondary structure of LDL. Mode of binding between aloin and LDL were obtained through spectroscopic measurements, which revealed significant binding characteristics. Molecular docking studies confirmed the interaction with a binding energy of -8.5kcal/mol, indicating a strong affinity between aloin and LDL. Furthermore, the stability of the aloin-LDL complex was validated by molecular dynamics simulations, showing that the secondary structure of LDL remained largely unchanged throughout the simulation period, indicating high stability of the complex. These findings open up new possibilities for using aloin in therapeutic applications aimed at cardiovascular health, potentially leading to the development of novel treatments or preventive measures for atherosclerotic cardiovascular diseases.

Al3+ and H+ substitutions in TiO2 polymorphs: Structural and vibrational investigations

Abstract Rutile is the most common TiO2 mineral on Earth’s surface and transforms to CaCl2- and α-PbO2-type structures at elevated pressures in subducted basaltic crusts. In this study, we synthesized hydrous CaCl2- and α-PbO2-type TiO2 crystals with various Al3+ concentrations using a multi-anvil press. Al3+ is incorporated into the CaCl2- and rutile-type phases mainly in the form of 3Ti4+ = 4Al3+, while the coupled substitution of Ti4+ = Al3+ + H+ is dominant in the α-PbO2-type structure, forming Ti1−x(AlH)xO2 solid solutions. Consequently, the water solubility in Al-bearing α-PbO2-type TiO2 is at least one order of magnitude greater than those in rutile- and CaCl2-type TiO2 phases, making TiO2 a significant water carrier at the pressure-temperature (P-T) conditions in the mantle transition zone (410 to 660 km depth in deep Earth’s interior), when coexisting with Al3+ and Fe3+. High-P and high-T Raman spectra were collected for these synthetic samples. The CaCl2- and α-PbO2-type phases irreversibly transform to a rutile-type structure at 950 K and ambient pressure. A reversible α-PbO2 → baddeleyite phase transition in TiO2 is detected at approximately P = 10 GPa and T = 300 K, and incorporating smaller amounts of Al3+ cations increases the phase transition pressure. The lattice vibrational modes typically shift to lower frequencies at elevated temperature and higher frequencies with increasing pressure due to variations in Ti(Al)-O bond length with temperature or pressure. Fourier transform infrared (FTIR) spectroscopic measurements were conducted on the samples under high-T or high-P conditions. Both T- and P-dependences are negative for the OH stretching vibrations in these TiO2 polymorphs, except that the OH bands in the α-PbO2-type samples exhibit a blueshift at elevated temperature. A negative linear correlation can be drawn between the measured OH stretching frequencies and the incorporated M3+O6 quadratic elongation, which were computed based on first-principles calculations. The local octahedral distortion can provide useful insights for understanding the M3+ and H+ incorporation mechanisms in TiO2 and SiO2 structures.

Design of magnetic polyethyleneimine-fluorescein isothiocyanate composites toward efficient enrichment of phosphopeptides.

Phosphoproteins maintain the normal metabolic activity of the organisms. Direct phosphopeptides detection is difficult to be realized by mass spectroscopy (MS) due to the low ionization efficiency, low abundance of phosphopeptides and interferences of complicated biological fluids. In the present work, a magnetic composite material was prepared by combining polyethyleneimine (PEI) and fluorescein isothiocyanate (FITC) focusing on phosphopeptides enrichment. Fourier-transform infrared spectroscopy, thermogravimetry analysis, X-ray photoemission spectroscopy, X-ray diffraction and UV-vis spectrometry measurement results confirmed the successful synthesis of Fe3O4@PEI@FITC material. FITC was facilely connected with PEI, and the two motifs endowed the efficient enrichment capacity of phosphopeptides by simple regulation of pH. The Fe3O4@PEI@FITC material was applied to the detection of phosphopeptides from real samples, implying that it can serve as an applicable platform for phosphoproteomics analysis.

Microstructural study with enhanced dielectric and magnetic properties of M−type Nd doped Ba1-xNdxFe12O19 (x = 0–0.20) hexaferrites synthesized via sol–gel auto-combustion route

In the present study, we have examined the influence of Nd doping on the structural, morphological, magnetic, and dielectric properties of barium hexaferrite (Ba1-xNdxFe12O19; 0 ≤ x ≤ 0.20) samples synthesized via the sol–gel auto-combustion route. The XRD patterns confirm the formation of the hexagonal phase, in addition to minor traces of Fe2O3 impurity in the samples. Doping with Nd3+ ions produced strain in the crystal, and the samples retain their hexagonal phase with space group P63/mmc, as ensured by the Rietveld refinement method. FTIR spectroscopy were performed for microstructural analysis, which shows the corresponding stretching and bending bands of iron and oxygen in the samples. The Raman spectra confirmed the Raman fundamental modes at various wavenumbers, which also confirm the hexagonal structure of the samples. The electronic states of all metal ions state were confirmed through x-ray photoelectron (XPS) spectroscopy analysis, which show that iron is present in two oxidation states (Fe2+ and Fe3+) in all the prepared samples. XPS spectra also revealed that the Nd-doped sample is more defective as compared to pure sample. Scanning electron microscopy (SEM) micrographs shows that the non-uniform particle size in the nanometer range. Elemental composition is confirmed using energy dispersive x-ray spectroscopy (EDS) measurement. Additionally, magnetic measurements using a vibrating sample magnetometer (VSM) revealed that the hysteresis loops for 5 % Nd-doped sample shows the maximum value 44.3 emu/g of magnetization, and its values decrease for further increase in Nd doping concentration. The dielectric measurements were performed at room temperature in the frequency range of 1 Hz to 10 MHz, when Nd3+ is doped at the Ba site, it enhances the dielectric constant, dielectric loss, tangent loss, and ac conductivity of the synthesized samples.

Dual-acting mechanism of microbial corrosion inhibition by ginger extract against nitrate-reducing bacteria in a nutrient-deficient environment.

This study investigates the efficacy of ginger extract (GE) as a green corrosion inhibitor in the petrochemical industry, specifically targeting microbial corrosion in carbon steel pipes utilized for river water coolant systems. The nutrient-deficient conditions coupled with the presence of nitrate-reducing bacteria (NRB) within these pipelines facilitate microbiologically influenced corrosion, wherein bacteria directly interact with the metal to harvest electrons for metabolic processes. Our findings indicate that GE inhibits microbial corrosion through dual mechanisms: significantly reducing biofilm formation and adsorbing onto the metal surface. Biofilm inhibition was assessed through both qualitative and quantitative assessments, employing light microscopy and confocal laser scanning microscopy (CLSM) to visualize and confirm the suppression of biofilm development by NRB in the presence of GE. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and polarization measurements, demonstrated that GE achieved an inhibition efficiency nearing 95%. Further analysis via scanning electron microscopy (SEM) and adsorption studies corroborated the effective adsorption of GE on carbon steel, highlighting the importance of concentration and immersion time in performance outcomes. Notably, elevated concentrations of GE were found to enhance inhibitory effects, with a 7-day exposure period yielding optimal surface coverage. These results establish GE as a promising and environmentally friendly alternative for mitigating microbial corrosion in industrial applications. PRACTITIONER POINTS: The presence of nitrate-reducing bacteria (NRB) and a nutrient-starved environment are commonplace in the coolant pipes carrying water and can cause severe damage to carbon steel pipes. Ginger extract (GE), an inexpensive green corrosion inhibitor, can be a potent microbial corrosion inhibitor in petrochemical industries. The high efficiency (95%), achieved with ginger extract (GE), is due to its dual-acting mechanism: It inhibits the formation of bacterial biofilm on the surface of carbon steel by providing a non-conducive environment for bacterial growth. The components of GE get adsorbed over the surface of carbon steel and hence prevent bacterial attachment. An optimal concentration of 0.5g/L GE was required to exhibit high efficiency (95%), which can be achieved on 7days of exposure of carbon steel to GE, in the presence of NRB in a nutrient-starved environment.

Advanced characterization of fish skin gelatin-proanthocyanidins covalent and non-covalent composite emulsions for benzyl isothiocyanate delivery.

This research endeavored to engineer robust delivery matrices for bioactives, specifically benzyl isothiocyanate (BITC), by harnessing the synergistic covalent and non-covalent interactions between fish skin gelatin (FSG) and proanthocyanidins (PC) to synthesize novel composite emulsions. The objective was to delineate the influence of these molecular interactions on the emulsion's structural integrity and stability, which are pivotal for the efficacious encapsulation and controlled release of BITC. Employing a suite of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, and contact angle measurements, the study delineated the predominant molecular forces at play within the FSG-PC complex, identifying electrostatic and hydrophobic interactions as the cornerstones of this interaction. An assessment of the emulsions' physicochemical properties, encompassing chromaticity, antioxidant efficacy, microstructural attributes, particle dimensions, zeta potential, and BITC retention, was undertaken to discern the optimal encapsulation strategy. The data unequivocally indicated that emulsions enriched with 0.06wt% PC, in non-covalent synergy with FSG, afforded the most pronounced stability and retention of BITC. This work paves the way for future studies and the translational application of FSG-PC composite emulsions in the realm of bioactive substance delivery, offering a promising avenue for innovation in pharmaceutical and nutraceutical formulations.

Raman and x-ray diffraction data analysis of Ge2Sb2Te5 films using gaussian approximation considering the temperature population factor

The structure particulars of amorphous Ge2Sb2Te5 thermally evaporated on glass substrates, as well as films annealed at temperatures of 500 and 700 K have been studied by the considering of experimentally established facts obtained from X-ray analysis and Raman spectroscopy measurements. The Debye-Scherrer and Williams-Hall methods were applied to the X-ray diffraction data for estimate the size of crystallites, interatomic distances, dislocation density and structure distortion degree. The features of heat treatment effect on numerical values of the above quantities at a given temperatures have been established. The analysis of the spectral distribution of Raman scattering was measured at light frequencies between 40 ÷ 300 cm-1 . The rather extended nature of the identified bands suggests the presence of several vibrational modes, leading to the appearance of individual spectral bands. To determine the vibrational modes, a reduced intensity was constructed from the experimental Raman spectrum data and the Gaussian approximation was applied to the latter. Having a mind the results of published works, the vibration modes existing in the samples obtained immediately after the process of layer application were determined, as well as the chemical nature and structure elements corresponding to these modes forming the amorphous matrix. The vibration modes in crystallized layers after heat treatment at the given temperatures were determined, as well as the chemical bonds and structural units forming their local structure.

Predicting Perovskite Photovoltaics Performance.

Wide band gap FA0.8Cs0.2Pb(I0.6Br0.4)3 perovskite photovoltaic (PV) devices are measured by spectroscopic ellipsometry in the through-the-glass configuration and analyzed to determine the complex optical property spectra of the perovskite absorber as well as the structural properties of all constituent layers. This information is used to simulate external quantum efficiency (EQE) spectra, to calculate PV device performance parameters such as short circuit current density, open circuit voltage, fill factor, and power conversion efficiency, and to develop strategies for increasing the accuracy of predictions. Simulations and calculations tend to overestimate PV device performance parameters, undermining the accuracy and usefulness of those simulations. Mapping spectroscopic ellipsometry measurements of an incomplete device are also collected from the perovskite film side to obtain layer thicknesses, perovskite band gap energies, and Urbach energies at each mapping point. The incomplete device stacks feature the perovskite absorber as the final deposited layer, while the complete devices add electron transport layers and silverback electrical contacts. When simulations are based on structural and optical properties obtained from spectroscopic ellipsometry measurements of incomplete PV device stacks, further inaccuracies arise as characteristics of the exposed perovskite film are not necessarily the same as those of an absorber in a complete, protected PV device. Predictions for PV performance parameters fall within 5% of the experiment for three of four baseline devices. The usefulness of this is apparent in situations where experimentally measuring PV device performance is unfeasible or overly tedious, as well as during intermediate steps during production.

Morphological Control of Y6 Thin Films Reveals Charge Transfer Is Facilitated by Co-facial Interactions.

The organic semiconductor Y6 has been extensively used as an acceptor in organic photovoltaic devices, yielding high efficiencies. Its unique properties include a high refractive index, intrinsic exciton dissociation, and barrierless charge generation in bulk heterojunctions. However, the direct impact of the crystal packing morphology on the photophysics of Y6 has remained elusive, hindering further development of heterojunction and homojunction devices. Herein, we study the photogenerated species in multiple distinct Y6 crystal packing geometries via transient absorption spectroscopy and photovoltaic measurements of the corresponding single-component devices. Our results reveal that "co-facial" interactions drive the generation of charge-transfer states in neat films of Y6 and that exciton dissociation can be switched on and off by controlling these interactions. Additionally, we find that a combination of long-range order and more co-facial packing interactions accelerates the charge-transfer generation process and increases the exciton to charge-transfer conversion efficiency. These insights provide valuable structure-property relationships for optimizing device performance.

Localized Effects in Graphene Oxide Systems: A Pathway to Hyperbolic Metamaterials

Graphene oxide (GO) has emerged as a carbon-based nanomaterial providing a different pathway to graphene. One of its most notable features is the ability to partially reduce it, resulting in graphene-like sheets through the elimination of oxygen-including functional groups. In this paper, the effect of localized interactions in an Ag/GO/Au multilayer system was studied to explore its potential for photonic applications. GO was dip-coated onto magnetron-sputtered silver, followed by the deposition of a thin gold film to form an Ag/GO/Au structure. Micro-Raman Spectroscopy, SEM and Variable Angle Ellipsometry (VASE) measurements were performed on the Ag/GO/Au structure. An interesting behavior of the GO deposited on magnetron-sputtered silver with the formation of Ag nanostructures on top of the GO layer is reported. In addition to typical GO bands, Micro-Raman analysis reveals peaks such as the 1478 cm−1 band, indicating a transition from sp3 to sp2 hybridization, confirming the partial reduction of GO. Additionally, calculations based on effective medium theory (EMT) highlight the potential of Ag/GO structures in hyperbolic metamaterials for photonics. The medium exhibits dielectric behavior up to 323 nm, transitions to type I HMM between 323 and 400 nm and undergoes an Epsilon Near Zero and Pole (ENZP) transition at 400 nm, followed by type II HMM behavior.

Synthesis, Characterization, and Toxicity Studies of Azo Dye Ligand for Metal Assessment in Different Brands of Lipsticks in Iraq

This research project focuses on the synthesis and characterization of a novel azo ligand, 4- CMBP, derived from 2-amino-6-methylbenzothiazole, and its complexes with Co(III) and Ni(II) ions. The study aims to investigate the structural and biological properties of the ligand and its complexes, with a particular emphasis on their potential applications in environmental and health sectors. The ligand and its complexes were characterized using techniques such as melting point measurements, nuclear magnetic resonance, mass spectrometry, Fourier-transform infrared spectroscopy, UV-Vis spectroscopy, elemental analysis, atomic absorption spectroscopy, molar conductivity, and magnetic susceptibility measurements. Biological activities were evaluated through the removal percentages of Co(III) and Ni(II) from eleven popular brands of lipsticks in the Iraqi market, antimicrobial screening against bacteria and fungi, in silico ADMET predictions, and anticancer activity tests in human liver cancer cell lines. Characterization confirmed the successful synthesis of the ligand and the formation of octahedral complexes with Co(III) and Ni(II) ions. The analysis revealed nickel concentrations ranging from 0.36 to 3.08 ppm, with varying safety implications. Antimicrobial screening showed promising activity, and in silico predictions indicated favorable oral bioavailability. The ligand and its complexes exhibited significant anticancer activity against liver cancer cell lines. The study successfully synthesized and characterized the azo ligand 4-CMBP and its metal complexes, highlighting their intriguing geometries and promising biological activities, with potential applications in environmental remediation, antimicrobial agents, and anticancer therapeutics.

Vitamin B2 Operates by Dual Thermodynamic and Kinetic Mechanisms to Selectively Tailor Urate Crystallization.

Here we demonstrate how a biologically relevant molecule, riboflavin (vitamin B2), operates by a dual mode of action to effectively control crystallization of ammonium urate (NH4HU), which is associated with cetacean kidney stones. In situ microfluidics and atomic force microscopy experiments confirm a strong interaction between riboflavin and NH4HU crystal surfaces that substantially inhibits layer nucleation and spreading by kinetic mechanisms of step pinning and kink blocking. Riboflavin does not alter the distribution of tautomeric urate isomers, but its adsorption on NH4HU crystal surfaces does interfere with the effects of minor urate tautomer by limiting its ability to induce NH4HU crystal defects while also suppressing NH4HU nucleation and inhibiting crystal growth by 80% at an uncharacteristically low modifier concentration. Time-resolved spectroscopy measurements, ab initio calculations, and molecular dynamics simulations confirm that each riboflavin molecule forms a complex with six or more urate molecules to lower supersaturation, thereby reducing the rate of NH4HU crystallization by a thermodynamically driven mechanism. The degree of complexation observed for riboflavin far exceeds that of common chelating agents, and results in crystal dissolution when the free urate concentration falls below NH4HU solubility. The synergism that is created by riboflavin's dual kinetic and thermodynamic mechanisms is rarely achieved by more conventional crystal growth inhibitors. These insights offer new approaches that could be influential for the design of molecular modifiers in crystal engineering applications, the development of therapeutics for pathological conditions, and establishing broader understanding of the roles played by foreign agents in natural and biological crystallization.

Engineering Oxygen Intermediates Adsorption on Amorphous NiFe Alloys for Highly Active and Selective Electrochemical Biomass Conversion

Electrochemical 5‐hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) offers a promising route to transform biomass into value‐added chemicals. However, the competing oxygen evolution reaction (OER) greatly limits the HMFOR selectivity. Herein, we report a facile doping strategy to engineer oxygen intermediates adsorption on amorphous NiFe alloys to boost highly selective electrochemical HMF oxidation to produce 2,5‐furandicarboxylic acid (FDCA), among which, amorphous Mn‐doped NiFeB alloy displays a low HMFOR onset potential of 1.35 V vs. RHE, achieving 100% HMF conversion with 88% FDCA selectivity at an applied potential of 1.4 V vs. RHE, outperforming amorphous NiFeB (73% FDCA selectivity) and Mo‐doped NiFeB (65% FDCA selectivity) alloys. Experimental characterizations suggest that the introduction of Mn/Mo into amorphous NiFeB alloy can increase/decrease its electronic density and thus strengthen/weaken oxygen intermediates adsorption. Operando experiments indicate that the amorphous Mn‐doped NiFeB alloy can significantly reduce the onset potential to form active Ni3+ species, which spontaneously react with HMF via nucleophile dehydrogenation to form FDCA. Furthermore, in‐situ infrared spectroscopy measurements verify that the HMF oxidation pathway follows the 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA) route rather than the 2,5‐diformyfuran (DFF) route.

Engineering Oxygen Intermediates Adsorption on Amorphous NiFe Alloys for Highly Active and Selective Electrochemical Biomass Conversion.

Electrochemical 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) offers a promising route to transform biomass into value-added chemicals. However, the competing oxygen evolution reaction (OER) greatly limits the HMFOR selectivity. Herein, we report a facile doping strategy to engineer oxygen intermediates adsorption on amorphous NiFe alloys to boost highly selective electrochemical HMF oxidation to produce 2,5-furandicarboxylic acid (FDCA), among which, amorphous Mn-doped NiFeB alloy displays a low HMFOR onset potential of 1.35 V vs. RHE, achieving 100% HMF conversion with 88% FDCA selectivity at an applied potential of 1.4 V vs. RHE, outperforming amorphous NiFeB (73% FDCA selectivity) and Mo-doped NiFeB (65% FDCA selectivity) alloys. Experimental characterizations suggest that the introduction of Mn/Mo into amorphous NiFeB alloy can increase/decrease its electronic density and thus strengthen/weaken oxygen intermediates adsorption. Operando experiments indicate that the amorphous Mn-doped NiFeB alloy can significantly reduce the onset potential to form active Ni3+ species, which spontaneously react with HMF via nucleophile dehydrogenation to form FDCA. Furthermore, in-situ infrared spectroscopy measurements verify that the HMF oxidation pathway follows the 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) route rather than the 2,5-diformyfuran (DFF) route.

Strain free thin film growth of vanadium dioxide deposited on 2D atomic layered material of hexagonal boron nitride investigated by their thickness dependence of insulator-metal transition behavior

Abstract We report preparation of Vanadium dioxide (VO2) ultrathin films on hexagonal boron nitride (hBN), which is a typical two-dimensional material, to show clear Metal -Insulator transition owing to weak van der Waals interaction at their surface. It is confirmed that VO2 films on hBN with the thickness ranging from 10 to 40 nm exhibit bulk like Metal -Insulator transition without degradation by using the Raman scattering spectroscopy and electric transport measurements. These results are demonstrating the importance of 2D material nature of hBN for producing the strain-free oxide thin films.

Enhanced Homogeneous Photocatalytic Hydrogen Evolution in a Binuclear Bio-inspired Ni-Ni Complex Bearing Phenanthroline and Sulfidophenolate Ligands.

The prominence of binuclearcatalysts underlines the need for the design and development of diverse bifunctional ligand frameworks that exhibit tunable electronic and structural properties. Such strategies enable metal-metal and ligand-metal cooperation towards catalytic applications, improve catalytic activity, and are essential for advancing multi-electron transfers for catalytic application. Hereby, we present the synthesis, crystal structure, and photocatalytic properties of a binuclear Ni(II) complex, [Ni2(1,10-phenanthroline)2(2-sulfidophenolate)2] (1), whichcrystallizes in the centrosymmetric triclinic system (P-1) showing extensive intra- and inter- non-coordinated interactions. The catalytic efficiency of 1 in a noble-metal-free photo-driven system using fluorescein as photosensitizer and triethanolamine as the electron donor, reaches TON 2900, threefold the efficiency of the corresponding homoleptic mononuclear complex [Ni(2-sulfidophenolate)2]. Efficiency rises up to 9000 TONs when thioglycolic-coated CdTe quantum dots are used as photosensitizers in the presence of ascorbic acid at pH 4.5.UV-Vis spectroscopy, DLS techniques, and Hg-poisoning measurements reveal that 1 maintains its molecular structure during catalysis. Electrochemical studies in DMF with TFA as the proton source were also performed for the elucidation of the mechanism of its catalytic action and its stability, suggesting that the proximity of two nickel ions plays a part in the increased catalytic activity, facilitating hydrogen evolution.

Comparison of plasma start-up with high Z and low Z first wall in WEST

Abstract The choice of first wall material is of paramount importance for the plasma start-up conditions in ITER and future fusion power plants. In this context, the present work focuses on the correlations between first wall impurity sources and total radiated power during plasma start-up in the tungsten (W) Environment in Steady-state Tokamak (WEST). The objective is to highlight experimental indications for a preferable combination of start-up plasma scenario and first wall materials. Until 2019, WEST featured a full high Z first wall with all limiters exposing only W surfaces to the plasma. To study the impact of a low Z first wall in WEST, boron nitride (BN) tiles were installed in the central part of the inner and outer limiters in 2020. Although visible spectroscopy and bolometry measurements show respectively a strong weakening of the WI line intensity on the limiters and a reduction of radiated power after the changeover, a degradation occurs with the accumulation of plasma exposure. In addition, the different plasma facing elements of the main chamber do not influence equally the radiated power during start-up. In both high Z and low Z environments, a clear non-linear dependence is found between the start-up radiated power and the outer limiter W impurity source. Since W seems to be the main cause for core radiation, correlation between outer limiter W sources and other impurity sources are investigated. Finally, analysis of the legacy of B powder drops on a number of start-up plasmas suggests that it is less effective at reducing radiated power when the first wall is covered with W.

Tuning optical and structural properties of polystyrene nanocomposites with rutile TiO₂ nanoparticles

ABSTRACT The surface morphology and structural properties of polystyrene (PS)/TiO₂ nanocomposites were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), while optical properties were assessed via UV-Vis spectroscopy and Fluorescence measurements. SEM images revealed uniform dispersion of TiO₂ nanoparticles with sizes ranging from 48 to 58.5 nm in the PS matrix, showing no significant agglomeration. XRD analysis revealed a decrease in crystallite size with increasing TiO₂ concentration. UV-Vis spectra demonstrated a decrease in the band gap with increasing TiO₂ concentration, indicating a shift towards enhanced visible light absorption. PL spectra excited at 330 nm revealed distinct emission peaks, with significant increases in intensity at higher TiO₂ concentrations, particularly at 399 nm and 422.5 nm, corresponding to near-band-edge and defect-related emissions. FTIR analysis demonstrated that the incorporation of TiO₂ led to disruption of C-O bonds in the PS matrix, particularly at 10% TiO₂, suggesting strong interactions between the TiO₂ nanoparticles and the polymer, which may weaken the polymer backbone. Overall, these findings suggest that TiO₂ incorporation not only impacts crystallite size and strain but also enhances the optical and fluorescence properties of PS/TiO₂ nanocomposites.