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A reduced pressure glow discharge is produced by passing a high-power pulsed DC source of 0–500 W with a frequency of 50 Hz across two parallel disk electrodes. A hydrogen peroxide aqueous solution is used as a flowing gas for discharge generation. Optical emission spectroscopy is employed to diagnose the discharge generated at a reduced pressure of 0.2 mbar with an electrode gap of 4 cm. The spectra are recorded at a power density of 9.4 mW/cm3 and typically lie in the visible wavelength range of 380–880 nm. The spectra are analyzed using the line intensity ratio method to estimate electron temperature and density. The results indicated that the electron temperature and density are, respectively, 0.87 eV and 6.4 × 1014 cm−3. [ABSTRACT FROM AUTHOR]

Helium metastable densities in the COST Reference Microplasma Jet are estimated for a variety of He/N2 admixtures and dissipated powers by applying a collisional-radiative model to absolutely calibrated optical emission spectroscopy measurements. This is accomplished by delineating the excitation mechanisms that result in the N2(C–B) and N 2 + (B–X) emission bands, the latter of which is strongly coupled to the presence of helium metastables. A number of other plasma parameters are established and discussed for each operating condition including the electron energy distribution function, reduced electric field, rate constants, and electron density. With these parameters, the reaction rates for the primary ionization pathways are also calculated, emphasizing the importance of helium metastables for discharge sustainment. Good agreement with the existing literature is found for most plasma parameters and for helium metastable densities, in particular. A clear [N2] − 1 relationship between the nitrogen concentration and density of helium metastables is demonstrated, as has been identified in previous studies in analogous atmospheric pressure plasma jets. This validates the efficacy of this optical technique for determining helium metastable densities and establishes it as a viable, and in many cases, more accessible alternative to other means of quantifying helium metastables in low-temperature plasmas. [ABSTRACT FROM AUTHOR]

As a threat to meeting the global demand for food created by the continued growth of population, different methods are being applied to enhance seed germination and plant growth. This study investigates the effect of hydrogen-rich water (HRW) and different plasma-activated waters (PAW) and their combinations including HRW, PAW1, PAW2, HPAW1, and HPAW2 on the seed germination of lentils. Different arc discharge reactors are generated under atmospheric pressure in the air. Optical emission spectroscopy was used to detect the radiative species formed in the plasma zone. Raman spectra and physicochemical properties of different waters were investigated. The results demonstrated significant differences in the properties of different activated waters compared to control water. On day 3 after treatment, the fraction and length of germinated seeds were evaluated. During germination, treated water significantly increased germination parameters such as final germination percentage, mean germination time, germination index, and coefficient of germination velocity. HPAW2 exhibited the highest germination index (GI), which combines germination percentage and speed. The plasma systems also effectively reduced the pH of PAW1 and PAW2, with a greater decrease observed in HPAW1 and HPAW1. Analysis of nitrite and nitrate levels revealed that HPAW2 had the highest concentrations, indicating more reactive processes in the presence of hydrogen. Based on our results, it can be concluded that lentil seed germination can be increased using PAW and hydrogenated PAW combined. [ABSTRACT FROM AUTHOR]

Standing striations with a unique pattern have been observed in a radio-frequency-generated hydrogen plasma. The striation pattern consists of a sequence of closely spaced bright ring doublets and two types of dark gaps of different widths. The bright and dark regions in striations were spectroscopically resolved with the Balmer series and the Fulcher band emission lines of hydrogen. Temperatures in these fine structures were determined. In general, the wider dark gap has a higher excitation temperature than the nearby narrower ones in the striation pattern sequence. Bright regions are rotationally hotter than the adjacent dark ones. However, for vibrational temperatures, the trends are not so obvious. No clear pressure dependence of temperatures was observed in striations within the pressure range of maintaining stable standing striations in this work. In addition to optical emission spectroscopy, we used graphite granules as in situ probes for plasma conditions in different striation regions. The striated hydrogen plasma-treated graphite granules were analyzed with Raman spectroscopy. The observed hydrogen-graphite interaction was correlated with the measured temperatures and the fine structures of striations in a discharge tube. [ABSTRACT FROM AUTHOR]

Pulsed discharge nozzles (PDNs) have been successfully used for decades to produce rotationally cold (Trot ∼ 20 K) radicals and ions of astrophysical interest and to characterize these species spectroscopically. In this work, an evolution of the PDN, the piezostack pulsed discharge nozzle (P2DN), is used for the first time to investigate the characteristics of the still poorly understood supersonic plasma expansion. The P2DN allows for a better control of the reservoir pressure of which an accurate measurement is required to characterize the plasma expansion. This new source, thus, gives the opportunity to further optimize the plasma conditions and extend its use to new target species. The spatial distribution of an argon plasma and the effect of the supersonic flow for different pressures are studied by combining a two-dimensional extended fluid model (extFM) and a direct simulation Monte Carlo (DSMC) method. The combined simulation is validated with experimental results obtained through emission spectroscopy associated with a group-code collisional-radiative model to retrieve the plasma parameters. The validated numerical approach (DSMC-extFM) allows for an accurate characterization of the plasma structure in our typical experimental conditions (a reservoir pressure ranging from 90 to 905 mbar). Thus, this simulation will be used in future studies to improve the plasma conditions to favor the synthesis of (transient) hydrocarbon species as found in space, by seeding the argon gas with a suitable precursor, such as acetylene. [ABSTRACT FROM AUTHOR]

GaCH2, a free radical thought to play a role in the chemical vapor deposition of gallium-containing thin films and semiconductors, has been spectroscopically detected for the first time. The radical was produced in a pulsed discharge jet using a precursor mixture of trimethylgallium vapor in high pressure argon and studied by laser-induced fluorescence and wavelength resolved emission techniques. Partially rotationally resolved spectra of the hydrogenated and deuterated species were obtained, and they exhibit the nuclear statistical weight variations and subband structure expected for a 2A2–2B1 electronic transition. The measured spectroscopic quantities have been compared to our own ab initio calculations of the ground and excited state properties. The electronic spectrum of gallium methylene is similar to the corresponding spectrum of the aluminum methylene radical, which we reported in 2022. [ABSTRACT FROM AUTHOR]

Optical emission spectroscopy studies of vanadium plasma in a cathodic-arc discharge in a nitrogen atmosphere have been carried out. Spectral lines of neutral atoms and ions of the cathode material V, V1+, and V2+, and nitrogen N2 and N2+ were observed in the discharge plasma. Analysis and comparison of the intensity of vanadium and nitrogen spectral lines as a function of nitrogen pressure showed that in vacuum excited ions V2+ and V+ are registered, with increasing pressure, the lines V+*, N2*, and N2+* are observed, and at pressures above 0.5 Pa, the neutral vanadium lines are additionally registered. The electron temperature of Te decreases from 5.9 to 3–4 eV with increasing pressure. Studies of cross-sectional scanning electron microscopy images of VN coatings deposited at different nitrogen pressures have shown that a dense, homogeneous, fine-grained microstructure is formed in the coating when the number of neutral V in the plasma is low, while in the presence of a large number of neutrals, the coating structure changes to a dense structure with columnar growth. [ABSTRACT FROM AUTHOR]

The role of ambient oxygen gas (O2) on molecular and nanoparticle formation and agglomeration was studied in laser ablation plumes. As a lab-scale surrogate to a high explosion detonation event, nanosecond laser ablation of an aluminum alloy (AA6061) target was performed in atmospheric pressure conditions. Optical emission spectroscopy and two mass spectrometry techniques were used to monitor the early to late stages of plasma generation to track the evolution of atoms, molecules, clusters, nanoparticles, and agglomerates. The experiments were performed under atmospheric pressure air, atmospheric pressure nitrogen, and 20% and 5% O2 (balance N2), the latter specifically with in situ mass spectrometry. Electron microscopy was performed ex situ to identify crystal structure and elemental distributions in individual nanoparticles. We find that the presence of ≈20% O2 leads to strong AlO emission, whereas in a flowing N2 environment (with trace O2), AlN and strong, unreacted Al emissions are present. In situ mass spectrometry reveals that as O2 availability increases, Al oxide cluster size increases. Nanoparticle agglomerates formed in air are found to be larger than those formed under N2 gas. High-resolution transmission electron microscopy demonstrates that Al2O3 and AlN nanoparticle agglomerates are formed in both environments; indicating that the presence of trace O2 can lead to Al2O3 nanoparticle formation. The present results highlight that the availability of O2 in the ambient gas significantly impacts spectral signatures, cluster size, and nanoparticle agglomeration behavior. These results are relevant to understanding debris formation in an explosion event, and interpreting data from forensic investigations. [ABSTRACT FROM AUTHOR]

Ultrafast optically excited ferromagnetic (FM)/nonmagnetic (NM) multilayer heterostructures have been demonstrated recently as efficient, high-power, and broadband sources of terahertz (THz) electromagnetic radiation. Since these spintronic THz emitters exploit the conversion from ultrafast spin to charge current, either in bulk or at the interface, the THz pulses inhere all the characteristics of the involved mechanisms and dynamics associated with spin-charge interconversion processes. Deconvolving the same requires meticulous and careful experimentation and analysis. In this article, we review the current state-of-the-art in this field and provide a perspective on the emerging phenomena, which are prospering as new research avenues and demonstrate application potential for futuristic THz technologies. In the process of developing efficient spintronic THz emitters by optimizing various conditions including those with material parameters and excitation light, it turns out that THz emission spectroscopy itself can be a unique experimental tool for probing microscopic dynamical magnetic and spintronic effects, induced by femtosecond laser pulse excitation, in a noncontact and noninvasive manner. Several breakthroughs can be listed from the literature in this regard from the last decade. Just recently, ultrafast orbitronics is another dimension that is taking shape and will impact the field immensely. A fair account to this topic is also presented in the article. [ABSTRACT FROM AUTHOR]

Recently, we predicted theoretically that in cavities that support several longitudinal modes, strong coupling can occur in very different manners, depending on the system parameters. Distinct longitudinal cavity modes are either entangled with each other via the material or independently coupled to the exciton mode. Here, we experimentally demonstrate the transition between those two regimes as the cavity thickness is gradually increased while maintaining fixed coupling strength. We study the properties of the system using reflection and emission spectroscopy and show that even though the coupling strength is constant, different behavior in the spectral response is observed along the coupling–decoupling transition. In addition, we find that in such multimode cavities, pronounced upper polariton emission is observed, in contrast to the usual case of a single-mode cavity. Furthermore, we address the ultrafast dynamics of the multimode cavities by pump–probe spectroscopic measurements and observe that the transient spectra significantly change through the transition. [ABSTRACT FROM AUTHOR]

In pursuit of diamond nanoparticles, a capacitively-coupled radio frequency flow-through plasma reactor was operated with methane-argon gas mixtures. Signatures of the final product obtained microscopically and spectroscopically indicated that the product was an amorphous form of graphite. This result was consistent irrespective of combinations of the macroscopic reactor settings. To explain the observed synthesis output, measurements of C2 and gas properties were carried out by laser-induced fluorescence and optical emission spectroscopy. Strikingly, the results indicated a strong gas temperature gradient of 100 K per mm from the center of the reactor to the wall. Based on additional plasma imaging, a model of hot constricted region (filamentation region) was then formulated. It illustrated that, while the hot constricted region was present, the bulk of the gas was not hot enough to facilitate diamond sp 3 formation: characterized by much lower reaction rates, when compared to sp 2, sp 3 formation kinetics are expected to become exponentially slow. This result was further confirmed by experiments under identical conditions but with a H2/CH4 mixture, where no output material was detected: if graphitic sp 2 formation was expected as the main output material from the methane feedstock, atomic hydrogen would then be expected to etch it away in situ, such that the net production of that sp 2-hybridized solid material is nearly a zero. Finally, the crucial importance of gas heating was corroborated by replacing RF with microwave source whereby facile sp 3 production was attained with H2/CH4 gas mixture. [ABSTRACT FROM AUTHOR]

In this study, functionally graded composite (FGC) was prepared using a high-energy ball mill by fabricating five layers of alumina (Al 2 O 3), titania (TiO 2), hydroxyapatite (HA), and iron oxide (Fe 3 O 4), which were sintered at 1100 °C to create an FGC sample. Scanning electron microscopy (SEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and weight loss measurements were used to assess bioactivity and biodegradation after immersing samples in simulated body fluid (SBF). Also, the antimicrobial activity and biocompatibility of these layers were evaluated. Furthermore, their electrical, dielectric, and mechanical properties were examined. The results revealed that all sintered layers were bioactive, and adding HA and Fe 3 O 4 enhanced this desired property. Also, S. aureus bacterial growth was inhibited by TiO 2 and Fe 3 O 4. Fortunately, the sintered layers showed no cytotoxic effect, validating the ICP findings that demonstrated acceptable biodegradation. Adding HA and Fe 3 O 4 enhanced fracture toughness in another hopeful outcome, which is crucial for biomaterial efficacy and long-term therapeutic success. Moreover, the compressive strength of all the layers and the FGC sample was 191.7, 182.2, 171.18, 159.8, 142.5, and 171.1 MPa. Layers 3, 4, and 5 notably had a compressive strength similar to cortical bone. This means that implanting these layers into human bone will protect the bone around them from stress-shielding action. Finally, the successive increase in HA/Fe 3 O 4 contents increased the electrical conductivity. Accordingly, the prepared FGC sample and its layers are attractive bone substitute materials. [ABSTRACT FROM AUTHOR]

In this article, we report the modification and photocatalytic evaluation of commercial TiO2-P25 under visible light for methyl orange (MO) dye degradation under visible light. The activity of materials doped with N, Pd, Pt and Au on to the TiO2-P25 was evaluated, with optimal photocatalytic performance achieved using Au nanoparticles doped on an N-functionalized titania surface. X-ray diffraction (XRD), physical nitrogen adsorption/desorption isotherm curves, transmission electron microscopy (TEM), diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to study the structural and textural properties of the samples. The chemical species present in the bulk and surface of the catalysts were identified using X-ray photoelectron spectroscopy (XPS) and microwave plasma-atomic emission spectroscopy. The results show that Au/N-TiO2 photocatalyst presents a remarkable enhanced activity for MO dye degradation, under visible light illumination, reaching 100% after 4 h. The enhanced photocatalytic activity using this composite is attributable to the well-dispersed and small size of Au nanoparticles, large surface area, reduction of band-gap energy and the interaction between nitrogen and Au which promoted a synergistic effect. This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'. [ABSTRACT FROM AUTHOR]

Propulsion performance produced by laser ablation of polymer made of acrylonitrile butadiene styrene is experimentally investigated using the first, second, and third harmonics of a Nd: YAG laser. A ballistic pendulum is employed to assess the impulse and coupling coefficient for laser propulsion application. Fast photography, target ablation, and optical emission spectroscopy are proposed to analyze the energy coupling characteristic. The impulse and coupling coefficient under different pressures are demonstrated to depend on the target ablation and plasma properties which are relevant to laser wavelength. As the laser wavelength decreases, the crater depth and ablation mass are enhanced. Meanwhile, the plasma plume separates at atmospheric pressure and its length extends continuously in the low-pressure range. As a result, plasma including more ejected particles with higher velocity contributes to obtaining excellent impulse and coupling coefficient. In addition, the decreased electron density and temperature indicate higher collision frequency and photoionization dominate rather than inverse bremsstrahlung absorption at shorter laser wavelengths. This work provides a better understanding of the energy conversion mechanism and a reference for improving propulsion performance. [ABSTRACT FROM AUTHOR]

This study introduces an innovative real-time instrumentation system that integrates Raman spectroscopy and Spark Emission Spectroscopy (SES) for the quantitative analysis of molecular structures and metal components in airborne particles. The study employs a nozzle-impact-based aerosol micro concentrator to enrich airborne particles for analysis. Experimental evaluations were conducted using laboratory-configured aerosols containing Cr2O3, Ni2O3, ZrO2, CuO mixed with SiO2, substances of significant concern in occupational health, notably in mining, metallurgy, and chemical industries. Results show a high linear correlation, with an R2 value exceeding 0.937, between spectral peaks and analyte mass. The concentration limit of detection (LOD) for SiO2, Zr, Cu, Cr, and Ni during a 10 min sampling period, with a flow rate of 2 L/min, were found to be 14.0, 64.6, 80.1, 13.8, and 5.5 μg/m3, allowing for precise quantification of the aerosol components. The plasma density and temperature were characterized for various samples with different deposition masses. The findings suggest that the developed system has the potential to provide real-time and accurate measurements of hazardous aerosol components, making it a useful tool for occupational health and environmental monitoring. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

High-ferrite cement (HFC) has attracted widespread attention due to its advantages, such as low sintering temperature and excellent corrosion resistance. The application of Cu-containing waste in HFC will promote the cement industry toward low-carbon and sustainable development. However, massive amounts of CuO can cause a delay in HFC hydration. The main aim of this paper was to investigate the retardation mechanism of CuO on the hydration of HFC using X-ray diffraction, mercury intrusion porosimetry, isothermal heat-conduction calorimetry, scanning electron microscopy, inductively coupled plasma-optical emission spectroscopy, thermogravimetric analysis and derivative thermogravimetry, among others. The results showed that compared with the undoped clinker, the maximum heat release peak of the clinker doped with 1.5% by weight of CuO was delayed for about 60 h, the hydration induction period was extended from 37 to 89 h, and the compressive strength was zero at 3 days. Through the study of cement suspension at 3 days, it was found that the retardation mechanism is mainly due to the obstruction of Ca leaching. On one hand, the C3S content in the HFC clinker decreases and the grain size of the calcium silicate minerals increases, on the other hand, the Ca2(OH)4·4Cu(OH)2·H2O coats clinker particles at the early stage, leading to a lower hydration degree of the HFC clinker. [ABSTRACT FROM AUTHOR]

Line intensity ratios (LIRs) of helium (He) atoms are known to depend on electron density, n e , and temperature, T e , and thus are widely utilized to evaluate these parameters, known as the H e I LIR method. In this conventional method, the measured LIRs are compared with theoretical values calculated using a collisional-radiative (CR) model to find the best possible n e and T e . Basic CR models have been improved to take into account several effects. For instance, radiation trapping can occur to a significant degree in weakly ionized plasmas, leading to major alterations of LIRs. This effect has been included with optical escape factors in CR models. A new approach to the evaluation of n e and T e from He I LIRs has recently been explored using machine learning (ML). In the ML-aided LIR method, a predictive model is developed with training data, which consists of an input (measured LIRs) and a desired/known output (measured n e or T e from other diagnostics). It has been demonstrated that this new method predicts n e and T e better than using the conventional method coupled with a CR model, not only for He but also for other species. This review focuses mainly on low-temperature plasmas with T e ⩽ 10 eV in linear plasma devices. [ABSTRACT FROM AUTHOR]

In this study, new peripherally substituted symmetric zinc and magnesium phthalocyanines (4 and 5) were successfully prepared by cyclotetramerization of the tetrahydropyrimidone (THPM)-linked phthalonitrile 3. The identity of the compounds were confirmed primarily through spectroscopic analysis including NMR, FT-IR, UV-Vis and MALDI-TOF mass spectroscopy. The photophysical and photochemical properties of the synthesized phthalocyanines (Pcs) were examined using UV–Vis absorption and fluorescence emission spectroscopy techniques. The quantum yields of singlet oxygen were found to be 0.50 and 0.33 for compounds 4 and 5 in DMSO, respectively. In addition to photo-physicochemical properties, the enhanced biological activities of compounds 4 and 5 were investigated using a range of biological assays, namely, antibiofilm, microbial cell viability, antioxidant, DNA cleavage, antimicrobial and photodynamic antimicrobial assays. The maximum DPPH inhibition of 4 and 5 was detected as 40.46% and 25.76% at 100 mg L−1, respectively. Fragmentation of the DNA molecule was observed at concentrations of 25 mg L−1, 50 mg L−1 and 100 mg L−1 for 4 and 5. Additionally, effective inhibition of microbial cell viability was observed with the targeted Pcs. The antibiofilm properties of these compounds were found to be concentration-dependent. The biofilm inhibition activities of 4 and 5 were found to be 96.01% and 92.04% for S. aureus, while they were 95.42% and 91.27%, for P. aeruginosa, respectively. The antimicrobial activities of 4 and 5 on different microorganisms were evaluated using the microdilution assay. In the case of photodynamic antimicrobial treatment, the newly synthesized Pcs showed more effective antimicrobial inhibition compared to the control. These findings suggest that compounds 4 and 5 can be used as promising photodynamic antimicrobial agents for the treatment of many diseases, particularly infectious diseases. [ABSTRACT FROM AUTHOR]

Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light‐induced proton reduction systems. Developing competitive base metal dyads is mandatory for a more sustainable future. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. A Fe─Co dyad that exhibits photocatalytic H2 production activity is studied using femtosecond X‐ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time‐dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the FeII photosensitizer to the cobaloxime catalyst. This novel approach enables the simultaneous measurement of the transient X‐ray emission at the iron and cobalt K‐edges in a two‐color experiment. With this methodology, the excited state dynamics are correlated to the electron transfer processes, and evidence of the Fe→Co electron transfer as an initial step of proton reduction activity is unraveled. [ABSTRACT FROM AUTHOR]

A three‐step synthetic route is established for the synthesis of a phosphorus‐containing ε‐caprolactam derivative, starting from cyclohex‐2‐enone and diphenylphosphinous chloride, followed by a Beckmann rearrangement. 2D NMR spectroscopy reveals that the phosphorus moiety is selectively localized at the 4‐position of the caprolactam ring. Different amounts of the phosphorus‐containing comonomer are systematically incorporated into polyamide 6 by anionic ring‐opening copolymerization with ε‐caprolactam at elevated temperatures. Polymerization reactions are initiated by a latent, CO2 protected N‐heterocyclic carbene in the presence of N‐acetyl caprolactam and MgCl2. The phosphorus content is determined by inductively‐coupled plasma‐optical emission spectroscopy (ICP‐OES) analysis. Limiting oxygen indices up to 23.5 are found for polymers containing ≈1 wt.‐% of phosphorus. The thermal properties of the copolymers are determined and compared to those of polyamide 6. [ABSTRACT FROM AUTHOR]

Household cleaning products (HCPs) are widely used; however, their airborne emissions and hazards have not been thoroughly studied. This study is aimed at evaluating the concentrations of volatile organic compounds (VOCs) and metals present in HCPs and the hazards associated with them. A total of 23 VOCs and 19 metals from 75 HCPs (four spray types and 14 intended usage categories) were analyzed using gas chromatography–mass spectrometry and inductively coupled plasma‐mass spectrometry/optical emission spectroscopy. The largest number of VOCs (21 of 23 ingredients) were detected in spray‐type and had the highest frequency (176). d‐Limonene was found in almost all products (69 of 75) and had the highest concentration. Benzene, a carcinogen, was detected in six spray‐type products. Only three of the 23 VOCs—d‐limonene, ethyl acetate, and heptane—appeared in three, one, and one product labels, respectively. Eight of 19 metals were primarily detected in spray‐type and spray foam‐type products, with sodium, magnesium, and calcium as the main components. Nickel, another carcinogen, was detected in both spray‐type and trigger‐type products. Caution is required when using spray‐type products, especially sticker/glue/tar/oil removers containing benzene and nickel. The study discovered that the VOCs and metals varied by their spray type and lacked sufficient harmful information. [ABSTRACT FROM AUTHOR]

Two isoelectronic and isostructural W(0) and Re(I) complexes mer-W(CO)3(PNP) (1) and [mer-Re(CO)3(PNP)]Cl (2) (PNP = 4,5-bis(diphenylphosphino)acridine) were synthesized and characterized by X-ray diffraction, infrared, electronic absorption and emission spectroscopy, and cyclic voltammetry. Structures of these complexes show a metal center bonded to the pincer ligand and two axial CO and one equatorial CO ligands. DFT calculations showed that the LUMOs of both complexes are the lowest energy π* orbitals localized in the acridine part of the ligand. The HOMO of 1 is dominated by the dπ orbital of W(0) while the HOMO of 2 has a substantial contribution from the highest energy π orbital of the acridine ring. TD-DFT calculations were performed to assist assignment of the UV-vis absorption spectra. The UV-vis absorption spectrum of 1 shows a very low energy W → π* (acridine) metal-to-ligand-charge-transfer (MLCT) absorption band that ranges from visible (500 nm) to near-infrared (>900 nm) regions and an intense acridine π → π* absorption band at 410 nm. There is a blue-green window in the ∼450–500 nm range between the π → π* and W → π*(acridine) MLCT absorptions. The absorption spectrum of 2, dominated by intense π → π* absorptions, shows no distinct low energy MLCT band. Complex 1 is luminescent, displaying acridine-based ππ* fluorescence at 501 nm which is anti-Kasha as it is higher in energy than the lowest energy excited state. [ABSTRACT FROM AUTHOR]

The interest in the production of nanoparticles (NPs) within Ar/C2H2 reactive plasmas is increasing, driven by their potential applications in functional materials or for their analogy to cosmic dust. The growth process of NPs has been thoroughly examined using a broad array of diagnostic tools. Significant among these tools are those that determine two-dimensional distributions of NP sizes and densities. The inherent complexity of these techniques has resulted in a limited number of works that integrate these measurements with a multitude of other diagnostic tools. Here, we show a multi-diagnostic exploration of the growing process of NPs in Ar/C2H2 plasmas. The combination of in-situ techniques, such as scattered light images, optical emission spectroscopy, light extinction, quadrupole mass signals, or self-bias voltage, with ex-situ scanning electron microscopy images and FTIR spectra of the deposited dust, provides a detailed picture of the growth process. The temporal evolution of plasma parameters, coupled with chemical composition measurements, provides a comprehensive description of the dust growth phases, and the FTIR measurements reveal an appreciable difference in chemical composition between the core and shell of the NPs. Furthermore, employing a method based on the terminal falling velocity of NPs in the afterglow, the intrinsic mass density of NPs is estimated. The asymmetries observed in the spatial distributions of NP size and density are qualitatively discussed in terms of neutral drag, ion drag, and electrostatic forces. [ABSTRACT FROM AUTHOR]

The present work investigates the etching of coated polytetrafluoroethylene (PTFE) films using an atmospheric pressure dielectric barrier discharge operating in nitrogen in a filamentary regime. For different treatment durations, the optical emission spectra were recorded over time. Most of the emissions are attributed to the N2 second positive system. The presence of CN is also observed, and its emissions rise with the exposure time of PTFE. This rise is attributed to the density of CN produced. The X‐ray photoelectron spectroscopy surface characterization suggests two etching regimes. This is linked with a change in slope in the intensity evolution of the optical emissions of the CN. At longer times, a fluorinated deposit on the electrode is observed, confirming a different nature of the etched material. [ABSTRACT FROM AUTHOR]

In this study, gas–liquid discharge plasma excited by nanosecond pulsed voltage is used to efficiently remove tiamulin (TIA) from water. The discharge produces a large number of reactive species (H2O2, OH radicals, NO3−, etc.) that can attack the TIA molecules. The effects of peak pulse voltage, initial TIA concentration, gas composition, and the addition of ferrous sulfate and persulfate on TIA removal were mainly investigated. The results showed that the oxygen plasma could approach 100% removal within 30 min of treatment time. The addition of the catalyst increased the TIA removal efficiency by approximately 15% during the 10‐min discharge treatment time. The toxicity of 12 intermediates was analyzed and the degradation mechanism of TIA was investigated. [ABSTRACT FROM AUTHOR]

Well-Root PT is a novel bioceramic material developed to overcome limitations of conventional calcium silicate cements. The purpose of this study was to assess the biocompatibility and bioactivity of a premixed putty-type cement, Well-Root PT. Identical cylindrical samples were prepared from ProRoot MTA, Biodentine, and Well-Root PT. In vitro calcium weight volume and calcium ion release from the materials were evaluated with scanning electron microscopy and energy-dispersive spectroscopy and inductively coupled plasma-optical emission spectroscopy. An in vivo rat direct pulp capping model was implemented with the materials (n = 14 per material). The rats were sacrificed at 7 or 28 days. Hematoxylin and eosin and immunohistochemical analyses were performed. In vitro calcium weight volume was 42.83 ± 8.82 % in ProRoot MTA, 47.05 ± 8.83 % in Biodentine, and 29.99 ± 4.94 % in Well-Root PT. Calcium ion releases from Well-Root PT after 7 and 28 days were similar with those from ProRoot MTA, but lower than those from Biodentine (P = 0.001 after 7 and 28 days equally). In an in vivo rat model, hematoxylin and eosin analysis showed no significant differences in inflammatory infiltration (P = 0.393) and hard tissue formation scores among the materials (P = 0.905). Also, both CD68 and DSPP expression showed similar results, with no significant differences among the materials (equally P = 0.874 for both markers). Within the limits of this study, Well-Root PT was comparable to ProRoot MTA and Biodentine in terms of biocompatibility and bioactivity. [ABSTRACT FROM AUTHOR]

The doping process is a unique method of changing the microstructure of a material, influencing its mechanical, thermal, and optical properties. Typically, the doping process is carried out via chemical reagents. In this work, we present a "green" method of doping photochromic TiO2 via low-temperature plasma. The doping agent was the electrode material that was sputtered during plasma burning. The process of electrode sputtering is confirmed by the emission spectroscopy data of the plasma zone and the mass loss of the electrodes. The doping process was confirmed by X-ray, Raman spectroscopy, and XPS analyses. The role of the dopant nature and the action of diaphragm discharge in improving the photochromic properties of titanium dioxide is considered. [ABSTRACT FROM AUTHOR]

Lithium sulfide was produced in a plasma system by the reaction of plasma-ionized sulfur with lithium metal. Thermodynamic calculations and optical emission spectroscopy were used to investigate the chemical behavior and reaction mechanism of lithium metal in sulfur plasma atmosphere. The effects of radiofrequency (RF) power and radiofrequency (RF) time on the properties of lithium sulfide prepared by the cold plasma method were investigated. The macroscopic morphology, microscopic morphology, elemental distribution and phase of the sulfide product (lithium sulfide) were further tested and analyzed. The results show that under the conditions of power ≥ 210 W and time ≥ 15 min, Li2S2-free lithium sulfide with high purity is generated; with the enhancement of power, lithium oxide is transformed into lithium sulfide. Subsequently, its electrochemical performance as a battery anode was tested. The test obtained: the specific capacity of charging is up to 216.9 mAh/g, and the specific capacity of discharging is up to 182.8 mAh/g; the impedance has a double capacitance to resist arcing, which can be carried out normally in the charging and discharging process, and it has a certain degree of electrochemical performance. [ABSTRACT FROM AUTHOR]

In this paper, a two‐step process is described for the chemoselective synthesis of highly fluorescent polycyclic chromeno[4,3,2‐ij]isoquinoline‐3‐carbonitriles using a sequential nucleophilic addition reaction involving 4‐chloro‐3‐vinyl coumarins, α,α‐dicyanoolefins and ammonium acetate as a source of nitrogen. In this process, it is believed that ammonium acetate is converted into ammonia and acetic acid during the reaction. Ammonia is the source of nitrogen, and the acid produced can catalyze the progress of the reaction. Single‐crystal X‐ray analysis was performed to confirm the structure of one of the typical products. In addition, the photophysical characteristics of the product 3 a were investigated through absorption and emission spectroscopy. This analysis reveals that the new heterocyclic system has impressive fluorescence characteristics. Several advantages of the presented synthetic strategy can be found in its simplicity, readily available starting materials, high‐efficiency products, highly chemoselective route, metal‐free catalyst, and ability to purify products by washing them with EtOH (96 %), a technique called GAP (Group‐Assisted‐Purification) chemistry. [ABSTRACT FROM AUTHOR]

The global demand for green energy stimulates the need for rechargeable batteries and their components, containing lithium, cobalt, manganese, copper, and nickel. Consequently, the quantitative determination of the battery metals has crucial importance in optimizing associated processes and waste management. The fundamental properties of an analyzer for continuous process and field measurements are sensitivity, selectivity, stability, mobility, and robustness. Unfortunately, these characteristics are lacking in numerous existing methods for metals monitoring. Hence, this gap led us to demonstrate the performance of micro-discharge optical emission spectroscopy (µDOES), a novel online trace metal analyzer. This study shows that the new online analyzer with its simple and compact design can match requirements for real-time determination of metals in aqueous solutions in the field. The performance of the system is defined with copper, nickel, and lithium dissolved in deionized water. The limit of detection (LOD) along with long-term repeatability for Cu, Ni, and Li in continuous analysis reached 0.9, 4.1, and 0.1 µg/L, and 2, 2, and 4.2%, respectively. The applicability of the technique to a real-world application is demonstrated by analyzing a hydrometallurgical black mass sample received from the recycling process of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A long-term sustainable tungsten cathode-solution anode glow discharge (SAGD) source for atomic emission spectrometry was developed for the determination of heavy metal elements. The tungsten cathode of this source was cooled by a compact refrigeration semiconductor, which is simple in design and able to operate at atmospheric pressure for long periods. When the equipment operates at its optimal conditions (75 mA discharge current, 2.0 mm discharge gap, 3.8 mL min−1 flow rate, and solution pH value of 2.0), the detection limits of Ag (338.24 nm), Cd (228.80 nm), Hg (253.66 nm), Pb (368.28 nm), Tl (337.52 nm), and Zn (213.79 nm) were explored, and the values were 0.030, 1.7, 7.2, 17, 0.24, and 25 μg L−1, respectively. The interference of coexisting ions in water, such as K+, Ca2+, Na+, Mg2+, and Li+, on the analytical performance of the solution anode glow discharge-atomic emission spectrometry (SAGD-AES) for Cd, Hg, Pb, and Zn were investigated. The results showed that coexisting metal ions' interferences are insignificant. The SAGD-AES system was successfully applied for analyzing water samples from the Yangtze River and Baixi River, and its accuracy and practicality were verified by comparison with inductively coupled plasma-optical emission spectrometry (ICP-OES) results. [ABSTRACT FROM AUTHOR]

The restriction of lead content in alloys for the production of solder, based on the Directive of the European Parliament and of the Council of the European Union of 8 June 2011, which is also known as RoHS (Restriction of the use of certain Hazardous Substances in electrical and electronic equipment), had a very positive impact on research into lead-free solder alloys, as well as on the economic impact of the production of solders. It opened the door to issues relating to the mechanical properties of lead-free solders and the microhardness of formed joints, with the aim of increasing their quality and efforts to reduce production costs. In addition to the production efficiency increase, without the need for the manual removal of so-called slagging, the moderation of oxide formation on the melt surface, standing for an increase in the yield of the total amount of solder, represents one of the many factors influencing the production of lead-free alloys for tin-based soldering. This work deals with the issues of material selection for the production of lead-free solders. Temperature affects the formation of different phases when there is a change in the concentration of the elements involved because it can be a negative aspect for soldering. Therefore, it is necessary to have detailed knowledge on the entire process that takes place during temperature changes. [ABSTRACT FROM AUTHOR]

In this study, zeolitic imidazolate framework 8 (ZIF-8) was coated on porous Ti6Al4V scaffolds, either bare or previously modified using hydroxyapatite (HA) or HA and gelatin (HAgel), via a growing single-step method in aqueous media using two contact times at 6 h and 24 h. The coated scaffolds termed ZIF-8@Ti, ZIF-8@ HA/Ti, and ZIF-8@HAgel/Ti were characterized via scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and molecular plasma-atomic emission spectroscopy (MP-AES). In order to assess the cell proliferation rate, the cytocompatibility of the scaffolds was evaluated in primary osteoblasts (hOBs) using alamarBlue assay, while the osteoconductivity was analyzed in hOBs using a real-time approach, evaluating the expression of secreted phosphoprotein 1 (SPP1). Osteopontin, which is the protein encoded by this gene, represents the major non-collagenous bone protein that binds tightly to HA. The scaffolds were shown to be non-cytotoxic based on hOB proliferation at all time points of analysis (24 h and 72 h). In hOB cultures, the scaffolds induced the upregulation of SPP1 with different fold changes. Some selected scaffolds were assayed in vitro for their antibacterial potential against Staphylococcus epidermidis; the scaffolds coated with ZIF-8 crystals, regardless of the presence of HA and gelatin, strongly inhibited bacterial adhesion to the materials and reduced bacterial proliferation in the culture medium, demonstrating the suitable release of ZIF-8 in a bioactive form. These experiments suggest that the innovative scaffolds, tested herein, provide a good microenvironment for hOB adhesion, viability, and osteoconduction with effective prevention of S. epidermidis adhesion. [ABSTRACT FROM AUTHOR]

Accurate measurement of metal concentrations in soil and water is vital for healthy crop production and decision making for environmental surveys. While there are a multitude of laboratory‐based soil analysis methods, such as inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), flame emission spectrometry, and atomic absorption spectroscopy, most are time and resource intensive. Additionally, there is a lack of information for rapid analysis of elements for aqueous soil extractions. The goal of this research is to establish elemental correlations between portable X‐ray fluorescence (pXRF) measurements of Mehlich III soil extractions and traditional elemental measurements via ICP‐OES. We hypothesize that certain metals can be accurately measured in aqueous soil extraction solutions by pXRF to the same degree as they are measured by ICP‐OES. To test this hypothesis, Mehlich III and 2% nitric acid solutions with known elemental concentrations were analyzed via ICP‐OES and pXRF. Soil samples extracted using Mehlich III were compared between ICP‐OES and pXRF to verify correlations. High correlations were found for As, Ca, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, V, and Zn in both the Mehlich III and 2% nitric acid solutions at concentrations between 5 and 85 mg L−1. P, S, and Si did not show high correlations at concentrations <100 mg L−1. These results indicate that between 5 and 85 mg L−1, pXRF analysis of aqueous solutions and soil extractions is a reliable technique; however, at low concentrations (i.e., <5 mg L−1 for metals and <100 mg L−1 for P and S), pXRF is not well suited. [ABSTRACT FROM AUTHOR]

A new N-(4-fluorobenzyl) N-(pyridin-2-ylmethyl) dithiocarbamate ligand (fbpm) having structural similarity to clinically approved antihistaminic drugs (viz. pheniramine, chlorpheniramine, and brompheniramine) and its four metal complexes [Co(fbpm)3] (1), [Ni(fbpm)2] (2), [Cu(fbpm)2] (3), and [Zn(fbpm)2] (4) were successfully synthesized and characterized by various techniques i.e. elemental analysis, FT-IR spectroscopy, HR-MS, NMR spectroscopy, and absorption and emission spectroscopy. Furthermore, complexes 1 and 2 were characterized by single crystal X-ray diffraction. Complex 1 adopts distorted octahedral geometry around the Co(III) center while complex 2 adopts distorted square planar geometry around the Zn(II) center. X-ray data also showed various weak intermolecular C–H⋯F and C–H⋯N hydrogen bonding interactions leading to supramolecular architectures in complexes 1 and 2. The thermal decomposition study of complexes 1–4 analyzed by TGA shows that they are thermally stable up to 150 °C and also gives strong evidence for the formation of respective metal sulfides at higher temperatures. The antihistaminic activity of the ligand (fbpm) and its complexes 1–4 was examined against clonidine and haloperidol-induced catalepsy in Swiss albino mice of either gender in an in vivo animal model. The result shows that these synthesized compounds have antihistaminic potential to inhibit clonidine-induced catalepsy and may be targeted for different allergic conditions. Complex 3 showed maximum reduction in clonidine-induced catalepsy after 180 minutes of treatment when compared with the induced control. [ABSTRACT FROM AUTHOR]

Understanding fast pedestal dynamics and turbulent transport in the edge and scrape-off layer (SOL) plasma of spherical tokamaks is crucial for the design and operation of future fusion reactors. The alkali beam emission spectroscopy diagnostic technique offers a means to measure the absolute electron density radial profile and fluctuation amplitude in these regions. In this study, we demonstrate that injecting a sodium neutral beam radially into the plasma and analyzing the light emission from its 3p–3s atomic transition using near-orthogonal viewing angles allows for accurate measurement of the electron density profile and fluctuations in the National Spherical Torus Experiment (NSTX) Upgrade spherical tokamak. Our findings indicate a peak signal-to-noise ratio of 118 in the pedestal and 12 in the SOL under typical NSTX plasma conditions. The spatial resolution for the electron density profile is estimated to be between 2 and 8 mm, while for fluctuation measurements, it ranges from 12 to 15 mm. [ABSTRACT FROM AUTHOR]

Large-scale plasma plumes downstream of plasma jets are in urgent need from a practical viewpoint. In this Letter, an argon plasma jet with floating electrodes is proposed to produce a large-scale planar plume array. Results indicate that with increasing peak voltage (Vp), the planar plume array elongates gradually and scales up in the lateral direction to an optimal value of 90.0 mm. There is only one discharge pulse per voltage half cycle, whose intensity and duration increase with increasing Vp. Moreover, there is a time lag between the initiations of individual plumes. Fast photography reveals that the planar plume array originates from the repeated process of some micro-discharge filaments stretching along the argon stream. By optical emission spectroscopy, the spatial distribution of plasma parameters is obtained, such as electron density, electron temperature, and gas temperature. At last, the planar plume array is employed to test the surface modification of polyethylene terephthalate, for which a uniform modification has been realized with a scan velocity of 1.0 cm/min. These results are of great significance for the development of large-scale atmospheric pressure plasma sources. [ABSTRACT FROM AUTHOR]

[Sn(H2PO4)2(TPyHP)](H2PO4)4∙6H2O (2), an ionic tin porphyrin complex, was synthesized from the reaction of [Sn(OH)2TPyP] (1) with a dilute aqueous solution of a polyprotic acid (H3PO4). Complex 2 was fully characterized using various spectroscopic methods, such as X-ray single-crystal crystallography, 1H NMR spectroscopy, elemental analysis, FTIR spectroscopy, UV–vis spectroscopy, emission spectroscopy, EIS mass spectrometry, PXRD, and TGA analysis. The crystal structure of 2 reveals that the intermolecular hydrogen bonds between the peripheral pyridinium groups and the axially coordinated dihydrogen phosphate ligands are the main driving force for the supramolecular assembly. Simultaneously, the overall association of these chains in 2 leads to an open framework with porous channels. The photocatalytic degradation efficiency of methyl orange dye and tetracycline antibiotic by 2 was 83% within 75 min (rate constant = 0.023 min−1) and 75% within 60 min (rate constant = 0.018 min−1), respectively. The self-assembly of 2 resulted in a nanostructure with a huge surface area, elevated thermodynamic stability, interesting surface morphology, and excellent catalytic photodegradation performance for water pollutants, making these porphyrin-based photocatalytic systems promising for wastewater treatment. [ABSTRACT FROM AUTHOR]

Accurate analysis of the rich information contained within X‐ray spectra usually calls for detailed electronic structure theory simulations. However, density functional theory (DFT), time‐dependent DFT and many‐body perturbation theory calculations increasingly require the use of advanced codes running on high‐performance computing (HPC) facilities. Consequently, many researchers who would like to augment their experimental work with such simulations are hampered by the compounding of nontrivial knowledge requirements, specialist training and significant time investment. To this end, we present Web‐CONEXS, an intuitive graphical web application for democratizing electronic structure theory simulations. Web‐CONEXS generates and submits simulation workflows for theoretical X‐ray absorption and X‐ray emission spectroscopy to a remote computing cluster. In the present form, Web‐CONEXS interfaces with three software packages: ORCA, FDMNES and Quantum ESPRESSO, and an extensive materials database courtesy of the Materials Project API. These software packages have been selected to model diverse materials and properties. Web‐CONEXS has been conceived with the novice user in mind; job submission is limited to a subset of simulation parameters. This ensures that much of the simulation complexity is lifted and preliminary theoretical results are generated faster. Web‐CONEXS can be leveraged to support beam time proposals and serve as a platform for preliminary analysis of experimental data. [ABSTRACT FROM AUTHOR]

The design, synthesis, and characterization of novel BODPY‐based iridium and ruthenium complexes were reported. The structures of new compounds were fully characterized by FT‐IR, MALDI‐TOF mass analysis, elemental analysis, 1H, and 19F NMR spectroscopies. Precursor BODIPY was characterized by single‐crystal x‐ray diffraction technique for the first time. Photophysical properties including absorption and emission profiles and lifetimes were investigated via UV–vis absorption and emission spectroscopy. Photochemical properties were investigated via direct method, and the singlet oxygen production capabilities of new complexes were determined by NIR phosphorescence methods. BODIPY‐based new complexes were efficient at producing 1O2. Besides, both complexes showed more remarkable photosensitization ability than some commonly used photosensitizer based on BODIPY derivatives. This study points out that novel complexes are effective 1O2 photosensitizers that might be used for different application areas like photodynamic therapy. [ABSTRACT FROM AUTHOR]

The anomalous increases or deficits in the human body can be detected by the development of accurate and sensitive methods for metal quantification in low-level concentrations. Two digestion procedures have been tested on whole blood samples for use in inductively coupled plasma optical emission spectrometry trace metal analysis (ICP-OES). The two procedures are, (microwave digestion with nitric acid and hydrogen peroxide), and (simple dilution digestion with nitric acid, N-butanol, and Triton X-100). According to the findings, the overall recoveries of all determining metals for the microwave digestion were in the range of (96%) of the expected levels, whereas for simple dilution digestion they were in the range of (85–88%) of the expected levels. The results showed a significant difference in the recovery ratios in favor of lead (Pd) and cadmium (Cd) between simple dilution and microwave digestion procedures. The findings also show that the content of these metals may be reliably measured using simple dilution and microwave digestion procedures. Abbreviations: ICP-OES: Induction coupled optical emission spectroscopy; LOD: Limit of detection; LOQ: Limit quantification; AAPCC: American Association of Poison Control Centers; NAUSS: Naif Arab University for Security Sciences; %RSD: Relative standard deviation). [ABSTRACT FROM AUTHOR]

Spectroscopy has held a pivotal role in advancing our comprehension of chemistry, dating back to its inception by Robert Bunsen and Gustav Kirchhoff. Nonetheless, access to advanced spectrometers remains restricted, particularly in high schools within developing nations. In this laboratory experiment, students were guided to fashion a spectrometer using reusable materials. This uncomplicated contrivance facilitated the exploration of emission and absorption spectroscopy, acquainting students with atomic spectra marked by electronic transitions, yielding line spectra. Conversely, molecules display not solely electronic transitions, but also vibrational and rotational shifts within chemical bonds, culminating in band spectra. Mobile phone cameras were enlisted as detectors. Captures of sodium and copper atoms emitting light in the course of a flame test, as well as depictions of molecular entities (copper sulphate pentahydrate and potassium permanganate aqueous solutions) absorbing light, were transmuted into the RGB (Red-Green-Blue) color model channels. The learning outcomes exhibited that 86 % of the students successfully discerned between an atomic spectrum and a molecular spectrum. Furthermore, 93 % of the students indicated that the incorporation of mobile devices in fostering scientific comprehension effectively seized their attention, resulting in heightened levels of engagement. [ABSTRACT FROM AUTHOR]

Existing etch endpoint detection (EPD) methods, primarily based on single wavelengths, have limitations, such as low signal-to-noise ratios and the inability to consider the long-term dependencies of time series data. To address these issues, this study proposes a context of time series data using long short-term memory (LSTM), a kind of recurrent neural network (RNN). The proposed method is based on the time series data collected through optical emission spectroscopy (OES) data during the SiO2 etching process. After training the LSTM model, the proposed method demonstrated the ability to detect the etch endpoint more accurately than existing methods by considering the entire time series. The LSTM model achieved an accuracy of 97.1% in a given condition, which shows that considering the flow and context of time series data can significantly reduce the false detection rate. To improve the performance of the proposed LSTM model, we created an attention-based LSTM model and confirmed that the model accuracy is 98.2%, and the performance is improved compared to that of the existing LSTM model. [ABSTRACT FROM AUTHOR]

During the hot pressing of pure titanium and different carbon steels in a temperature range of ϑ = 950–1050 ° C , a compound layer up to dL≈10 μ m thick is formed at the titanium–steel interface. With a higher carbon content of the used steel, the layer thickness increases. The carbon concentration within the layer is in the range of stoichiometry for TiC. Apart from TiC, no other phases can be detected by X-ray diffraction (XRD) measurements inside the formed layer. The calculation of the activation energy for the TiC layer formation is Q = 126.5–136.7 kJ mol−1 and is independent of the carbon content of the steel. The resulting microstructure has a grain size gradient, wherein the mechanical properties, such as hardness and Young's modulus, are almost constant. Statistical analysis using Response Surface Methodology (RSM) indicates that the carbon content of the steel has the most significant influence on layer thickness, followed by annealing temperature and annealing time. By selecting the appropriate carbon steel and the subsequent removal of the steel, it is possible to produce targeted TiC layers on titanium substrates, which holds enormous potential for this material in wear-intensive applications. [ABSTRACT FROM AUTHOR]

The selectivity of the reactive ion etching of silicon using a negative electron resist AR-N 7520 mask was investigated. The selectivity dependencies on the fraction of SF6 in the feeding gas and bias voltage were obtained. To understand the kinetics of passivation film formation and etching, the type and concentration of neutral particles were evaluated and identified using plasma optical emission spectroscopy. Electron temperature and electron density were measured by the Langmuir probe method to interpret the optical emission spectroscopy data. A high etching selectivity of 8.0 ± 1.8 was obtained for the etching process. The optimum electron beam exposure dose for defining the mask was 8200 pC/m at 30 keV. [ABSTRACT FROM AUTHOR]

Plasma-liquid interactions yield numerous physicochemical phenomena, rendering them promising for various applications. Plasma-based technology is proposed for water treatment due to its high efficiency in removing contaminants unattainable by conventional techniques. In this study, we employ an argon microwave plasma jet (MWPJ) to investigate methylene blue (MB) degradation. We observe a significant enhancement in the MB degradation rate in a covered system, attributed to increased air humidity promoting hydroxyl radicals (OH) production, which degrade approximately 95% of MB. Furthermore, the injection of O2 gas into the solution under the plasma generates more hydrogen peroxide (H2O2), around 30 mg/L compared to approximately 20 mg/L without injection, although the MB degradation efficiency is reduced. We evaluate MB degradation under various solution properties, revealing that increasing electrical conductivity decreases the MB degradation rate until it becomes independent for conductivities > 10,000 µS/cm. In these latter conditions, a non-conventional temporal evolution of solution conductivity was observed: a decrease during the first tens of minutes followed by a continuous increase for longer treatment time. Conversely, solution acidity minimally affects the MB degradation rate. The MWPJ is characterized by optical emission spectroscopy, showing stability over time and under various solution properties. The energy yield (Y50%) consistently demonstrates superior performance of the MWPJ in a closed environment compared to an open-to-air environment. Although its efficiency is relatively low compared to other systems, we anticipate improvements through parameter adjustments. [ABSTRACT FROM AUTHOR]

Hydrofluorocarbon gas chemistries have long been favored for SiO2 etching. However, the fluorocarbon polymer generated during the process not only assists in obtaining a high selectivity, but also leads to chamber wall contamination. The adhesion efficiency of the polymer depends on the chamber wall temperature, which needs to be well-controlled to ensure controllable polymer deposition rate and etch characteristics. Similarly, the increasing gas temperature during the process is also expected to increase the production rate of polymer precursors. Hence, it is important to properly condition the chamber so that a sufficiently high and stable chamber temperature is reached before starting the actual process. This work utilizes an Inductively Coupled Plasma Reactive Ion Etcher to optimize a multi-cycle chamber conditioning process for two C4F8/H2-based chemistries. We use the integrated optical emission spectroscopy (OES) tool to show that the dependence of etch characteristics on conditioning time is much stronger for the highly polymerizing chemistry. For a low conditioning time (< 15 min), the instability of plasma species indicate that the chamber temperature has not yet plateaued, resulting in a ⁓60% decrease of recess in the underlying silicon layer during the lot processing time. By conducting systematic etch tests, we analyze the behavior of key OES peaks to identify the optimal conditioning time (≥ 30 min) for this recipe, which results in only a 13% decrease in silicon recess depth during the processing time. Subsequently, a method to assess the stability of plasma species during the conditioning process is devised, assisting in advance to identify the optimal moment to initiate the lot process. By comparing the experimental results of the two etch recipes, we also highlight the important correlation between conditioning time and polymerizing degree of the chemistry. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of a sensitive AKBA-Based fluorescent “Turn off” chemosensor for rapid detection of abamectin residues in tomatoes. Silver nanoparticles were synthesized by using 3-O-acetyl-11-keto-β-boswellic acid (β-AKBA) by chemical reduction method. The characterization of AKBA-AgNPs was performed by UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The average particle size of NPs was found to be 46.2 ± 2 nm with lumps of macro-sized particles. TEM data further revealed that nanoparticles were polydispersed and spherical in shape and also show good stability at high temperatures and pH. The biosensing properties of nanoparticles were studied for the detection of abamectin residues in tomato samples. Abamectin a natural product derived from the bacterium Streptomyces avermitilis is effective against a wide range of pests. In sensing protocol 67 organic tomato samples were segregated into 34 (safe group, without a spray of abamectin) and 33 samples (as an unsafe group, sprayed with abamectin insecticide solution). Emission spectra of these sample solutions were measured in the wavelength range of 450–530 nm, excitation wavelength was fixed at 488 nm. The effect of minor wavelength variation for the discrimination and classification of the two groups was investigated by applying two chemometric methods including partial least square discriminant analysis and principal component analysis with projection. The mechanism of its interaction between the AKBA-Ag NPs and abamectin residue was also established through UV/visible, FTIR, and TEM microscopy. This newly synthesized nanoparticle was found to have excellent stability at variables, i.e., temperature, storage period, salt concentration, and pH. Therefore, the synthesized Ag NPs are potential candidates for biosensing applications against abamectin.

The morphology and crystalline quality of polycrystalline diamond samples were studied by systematically varying the flowrate of nitrogen gas in the microwave plasma. A slight improvement in both crystallite size and crystalline quality is observed for a low concentration of 0.5 sccm nitrogen. With a further increase in nitrogen concentration, diamond switches from micro-crystalline to nanocrystalline (NCD) with a nitrogen flow of 2.5 sccm (10% of methane concentration). The surface roughness of the sample is found to depend strongly on the crystallite size of the sample. Extensive spectroscopic studies have been done to understand the presence and formation of different defect complexes in diamond. XPS and Raman analysis of the films reveal the variation of graphitic content as a function of nitrogen addition. The presence of nitrogen-containing defect complexes has been studied thoroughly and their concentration has been found to be limited by the solubility limit rather than the availability of reactants in the gas environment. In contrast, the effect these complexes have on the strain of the diamond film is found to be negligible. Optical emission spectroscopy of the plasma reveals the presence of C2 dimers as well as C-N radicals. However, they have little role in modifying diamond grain morphology or crystalline quality. [ABSTRACT FROM AUTHOR]

The slow evaporation solution growth technique (SEST) was used to successfully grow inorganic single crystals of sodium sulphamate (NaS) in ambient conditions. The titled crystal's structural and optical characteristics were evaluated using a variety of spectroscopic techniques. Powder X-ray diffraction (PXRD) analysis and Fourier transform infrared (FT-IR) spectroscopy were used to examine the crystal structure characteristics. Using UV-Vis spectroscopy, the optical properties of the NaS crystal were carefully examined, and the optical bandgap was determined using Tauc's plot. The HR-XRD analysis examined crystalline perfection. Additionally, photoluminescence spectroscopy determined the emission spectra, and time-resolved photoluminescence measured the decay rate. The Z -scan technique was also used to examine the titled crystal's nonlinear optical (NLO) performance. [ABSTRACT FROM AUTHOR]