Electron Spectroscopy Research Articles

Electron-induced hydrogen desorption from selected polymers (polyacetylene, polyethylene, polystyrene, and polymethyl-methacrylate)

Elastic Peak Electron Spectroscopy, abbreviated as EPES, involves the analysis of the line shape found in the elastic peak. The reduction in the energy of electrons within the elastic peak is a result of energy being transferred to the target atoms, a phenomenon referred to as recoil energy. EPES distinguishes itself among electron spectroscopies by its unique ability to identify hydrogen in polymers and hydrogenated carbon-based materials. This distinctiveness is particularly notable because lighter elements demonstrate more pronounced energy shifts. The detection of hydrogen in polymers entails measuring the energy difference between the positions of the carbon (or carbon+oxygen) elastic peak and the hydrogen elastic peak. This difference tends to increase as the kinetic energy of the incident electrons rises. Concerning hydrogen peak intensity, electron beam-induced damage represents a critical aspect of EPES, as hydrogen desorbs under electron irradiation. In this study, the Monte Carlo method was employed to simulate EPES spectra involving electrons interacting with polyacetylene (C2H2), polyethylene (C2H4), polystyrene (C8H8), and polymethyl-methacrylate (C5H8O2) and to evaluate electron-induced hydrogen desorption from these polymers.

SYNTHESIS, CHARACTERIZATION, DFT, AND BIOLOGICAL ASSAY OF NEW XANTHATE COMPLEXES WITH NITROGEN BASES

This study introduces a new series of complexes and adducts, denoted by [M(2-PhOEtXant)2.nL], where M represents Mn(II), Fe(II), Co(II), or Ni(II), and the ligand (2-PhOEtXant) is 2-Phenoxyethylxanthate. Varying ligands, including pyridine, piperidine, quinoline, ethylenediamine, and (1,10)-phenanthroline, are explored based on the value of n. Comprehensive characterization, encompassing techniques like 1H-NMR, 13C-NMR, FTIR, AA, CHN analysis, UV-visible spectroscopy, and magnetic property measurements, is employed. Results indicate an octahedral geometry for these complexes, as revealed by effective magnetic moment measurements and electronic spectra analysis. The compounds exhibit noteworthy antioxidant properties, demonstrated through the DPPH radical scavenging method, highlighting their potential as effective antioxidants. Moreover, the complexes display enhanced antibacterial activity against microbial strains compared to free ligands. This research not only delves into the coordination chemistry of these complexes but also underscores their diverse applications. Combining experimental methods with computational insights using Density Functional Theory (DFT) enhances the understanding of dithiolate transition metal complexes. The alignment of computational and experimental outcomes strengthens the reliability of the findings, laying a robust foundation for interdisciplinary exploration. The identified potential applications in optoelectronics, along with the notable antioxidant and antibacterial activities, position these complexes as promising contenders for advanced technologies and scientific applications.

Radiationless decay spectrum of O 1s double core holes in liquid water.

We present a combined experimental and theoretical investigation of the radiationless decay spectrum of an O 1s double core hole in liquid water. Our experiments were carried out using liquid-jet electron spectroscopy from cylindrical microjets of normal and deuterated water. The signal of the double-core-hole spectral fingerprints (hypersatellites) of liquid water is clearly identified, with an intensity ratio to Auger decay of singly charged O 1s of 0.0014(5). We observe a significant isotope effect between liquid H2O and D2O. For theoretical modeling, the Auger electron spectrum of the central water molecule in a water pentamer was calculated using an electronic-structure toolkit combined with molecular-dynamics simulations to capture the influence of molecular rearrangement within the ultrashort lifetime of the double core hole. We obtained the static and dynamic Auger spectra for H2O, (H2O)5, D2O, and (D2O)5, instantaneous Auger spectra at selected times after core-level ionization, and the symmetrized oxygen-hydrogen distance as a function of time after double core ionization for all four prototypical systems. We consider this observation of liquid-water double core holes as a new tool to study ultrafast nuclear dynamics.

Epitaxial Fe/Rh bilayers for efficient spin-to-charge conversion

To address the spin pumping in the conventional ferromagnetic/“normal” metal systems, we fabricated 6 nm Fe/1–15 nm Rh epitaxial bilayers and determined the g-factor, magnetic anisotropy, and magnetization damping by combining both 0–40 GHz CPW-based frequency-dependent and cavity-based 9.56 GHz in-plane angular-dependent ferromagnetic resonance measurements at room temperature. Auger electron spectroscopy and low-energy electron diffraction show that Rh grows epitaxially on Fe. The epitaxial bilayers exhibit a high spin mixing conductance gmix↑↓=(2.9±0.2)×1019 m−2 and a spin diffusion length in Rhodium λsd=9.0±1.3 nm. This makes Rh comparable to Pt and Pd in terms of spin pumping and spin transport efficiency at room temperature.

Remote plasma chemical vapor deposition of silicon oxycarbide film with a styrene-containing precursor and in situ O2 plasma treatment

In this paper, a study was conducted on silicon oxycarbide thin-film deposition using remote plasma chemical vapor deposition. A di-methyldimethoxysilane)2styrene (MDMS)2styrene precursor and CH4 plasma were used in the deposition process, and in situ oxygen plasma treatment was performed to control the carbon content and properties of the thin film. During the deposition process, the thin-film growth rate was found to be almost constant regardless of in situ plasma treatment. This means that in situ oxygen plasma treatment had no significant effect on thin-film growth itself. Auger electron spectroscopy analysis revealed that the carbon content of the deposited thin film was 43 % when only deposition was performed, but could be lowered to 3 % by in situ oxygen plasma treatment, which demonstrated that the carbon content can be controlled in a relatively wide range. X-ray photoelectron spectroscopy showed that it was possible to preserve SiC bonds even as the oxygen content increased with the number of in situ plasma treatments. The refractive index increased from 1.33 to 1.49, indicating a decrease in the number of pores and an increase in density. Meanwhile, the dielectric constant increased with the oxygen content, but did not exceed 3.9 due to the SiC bond structure. As the pore size decreased, the leakage current tended to decrease to 9.51 × 10−9 A/cm2 in an electric field of 1 MV/cm, and the breakdown voltage increased. Finally, it was possible to improve the etching characteristic through plasma treatment by lowering the wet etch rate from 78 to 19 Å/min.

Insights into the Volatile Flavor Profiles of Two Types of Beef Tallow via Electronic Nose and Gas Chromatography-Ion Mobility Spectrometry Analysis.

In the current study, an electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS) were employed to investigate the volatile flavor compounds (VFCs) of intense flavor beef tallow (L) and ordinary beef tallow (P). The study results indicate that an E-nose combined with an LDA and GC-IMS combined with an OPLS-DA can effectively distinguish between the two types of beef tallow. Compared with ordinary beef tallow, the E-nose sensors of intense flavor beef tallow have stronger response signals to sulfides, terpenes, and nitrogen oxides. A total of 22 compounds contribute to making the flavor of intense flavor beef tallow more typical and richer; in contrast, ethyl acetate was the main aroma-active compound found in the ordinary beef tallow. Sulfur-containing compounds and terpenoids might be the key substances that cause sensory flavor differences between the two types of beef tallow. In conclusion, the results of this study clarify the characteristics and differences of the two types of beef tallow and provide an enhanced understanding of the differences in the flavors of the two types of beef tallow.

Transparent Conductive Titanium and Fluorine Co-doped Zinc Oxide Films.

Aerosol-assisted chemical vapor deposition (AACVD) was used to deposit highly transparent and conductive titanium or fluorine-doped and titanium-fluorine co-doped ZnO thin films on glass substrate at 450 °C. All films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV-Vis spectroscopy, scanning electron spectroscopy (SEM), and four-point probe. The films were 600-680 nm thick, crystalline, and highly transparent (80-87 %). The co-doped film consisted of 0.70 at % titanium and 1 at % fluorine, and displayed a charger carrier mobility, charge carrier concentration, and a minimum resistivity of 8.4 cm2 V-1 s-1, 3.97×1020 cm-3, and 1.69×10-3 Ω cm, respectively. A band gap of 3.6 eV was observed for the co-doped film. Compared to the undoped and singly doped films, the co-doped film displayed a notably higher structure morphology (more homogenous grains with well-defined boundaries) suitable for transparent conducting oxide applications.

Electron-induced deposition using Fe(CO)4MA and Fe(CO)5 - effect of MA ligand and process conditions.

The electron-induced decomposition of Fe(CO)4MA (MA = methyl acrylate), which is a potential new precursor for focused electron beam-induced deposition (FEBID), was investigated by surface science experiments under UHV conditions. Auger electron spectroscopy was used to monitor deposit formation. The comparison between Fe(CO)4MA and Fe(CO)5 revealed the effect of the modified ligand architecture on the deposit formation in electron irradiation experiments that mimic FEBID and cryo-FEBID processes. Electron-stimulated desorption and post-irradiation thermal desorption spectrometry were used to obtain insight into the fate of the ligands upon electron irradiation. As a key finding, the deposits obtained from Fe(CO)4MA and Fe(CO)5 were surprisingly similar, and the relative amount of carbon in deposits prepared from Fe(CO)4MA was considerably less than the amount of carbon in the MA ligand. This demonstrates that electron irradiation efficiently cleaves the neutral MA ligand from the precursor. In addition to deposit formation by electron irradiation, the thermal decomposition of Fe(CO)4MA and Fe(CO)5 on an Fe seed layer prepared by EBID was compared. While Fe(CO)5 sustains autocatalytic growth of the deposit, the MA ligand hinders the thermal decomposition in the case of Fe(CO)4MA. The heteroleptic precursor Fe(CO)4MA, thus, offers the possibility to suppress contributions of thermal reactions, which can compromise control over the deposit shape and size in FEBID processes.

PRECIPITATION OF ARSENIC FROM THERMAL WATER

The presented scientific research reveals the results of experiments on the precipitation of arsenic in the form of sulfide (As2S3) from the Daridag thermal water using sodium sulfide as a reagent. The main factors impacting the precipitation of the As2S3 compound were determined: the amount of precipitant (Na2S), the ratio of solid and liquid phases (S:L), pH of the initial solution, precipitation time and temperature, also optimal parameters were obtained. According to the results obtained, the yield during precipitation of arsenic tri-sulfide from from thermal water under certain temperature conditions (t=30-450С, pH=1-2; S:L - 1:1000; = 30-50 min.) were 99.6 %. The properties of the samples were studied by physicochemical research methods (X-Ray, SEM/EDS). X-ray phase analysis showed that the sediment sample obtained under these conditions is X-ray amorphous. The composition and morphology of the obtained sample was confirmed by scanning electron microscopy and spectroscopy (SEM/EDS)

Effects of phantom microstructure on their optical properties.

Developing stable, robust, and affordable tissue-mimicking phantoms is a prerequisite for any new clinical application within biomedical optics. To this end, a thorough understanding of the phantom structure and optical properties is paramount. We characterized the structural and optical properties of PlatSil SiliGlass phantoms using experimental and numerical approaches to examine the effects of phantom microstructure on their overall optical properties. We employed scanning electron microscope (SEM), hyperspectral imaging (HSI), and spectroscopy in combination with Mie theory modeling and inverse Monte Carlo to investigate the relationship between phantom constituent and overall phantom optical properties. SEM revealed that microspheres had a broad range of sizes with average and were also aggregated, which may affect overall optical properties and warrants careful preparation to minimize these effects. Spectroscopy was used to measure pigment and SiliGlass absorption coefficient in the VIS-NIR range. Size distribution was used to calculate scattering coefficients and observe the impact of phantom microstructure on scattering properties. The results were surmised in an inverse problem solution that enabled absolute determination of component volume fractions that agree with values obtained during preparation and explained experimentally observed spectral features. HSI microscopy revealed pronounced single-scattering effects that agree with single-scattering events. We show that knowledge of phantom microstructure enables absolute measurements of phantom constitution without prior calibration. Further, we show a connection across different length scales where knowledge of precise phantom component constitution can help understand macroscopically observable optical properties.

Electron Spectroscopy and Microscopy: A Window into the Surface Electronic Properties of Polycrystalline Metal Halide Perovskites.

In the past years, an increasing number of experimental techniques have emerged to address the need to unveil the chemical, structural, and electronic properties of perovskite thin films with high vertical and lateral spatial resolutions. One of these is angle-resolved photoemission electron spectroscopy which can provide direct access to the electronic band structure of perovskites, with the aim of overcoming elusive and controversial information due to the complex data interpretation of purely optical spectroscopic techniques. This perspective looks at the information that can be gleaned from the direct measurement of the electronic band structure of single crystal perovskites and the challenges that remain to beovercame to extend this technique to heterogeneous polycrystalline metal halide perovskites.

Fabrication and characterization of rubidium ferrites by the solution‐based combustion method using diverse organic fuels

Fabrication and characterization of rubidium ferrites by the solution‐based combustion method using diverse organic fuels

Ohmic junction ZnIn2S4/MoP for efficient photocatalytic hydrogen evolution

In this paper, coupling MoP onto ZIS surface using solvothermal method to form ohmic heterojunction. The photocatalytic performance of ZIS/MoP is significantly better than that of ZIS and MoP monomers, and the hydrogen evolution efficiency of the composite material reaches 2.031 mmol g−1·h−1, 50 and 18 times the hydrogen production efficiency of MoP and ZIS. The quantum apparent efficiency (AQE) reaches 10.5 %. The improvement of the photocatalytic performance of ZIS/MoP is attributed to the generation of Ohmic heterojunctions. An Ohmic heterojunction is formed when MoP attaches to the surface of ZIS as an electron acceptor, In one aspect, the electron transfer path of Ohmic heterojunctions improves the separation efficiency of electrons and holes, enhances the charge transfer efficiency. ln the other aspect, ZIS greatly improves the visible light absorption of ZIS/MoP. To confirm the photocatalytic mechanism and Ohmic heterojunction structure, characterization methods such as X-ray photoelectron spectroscopy (XPS), ultraviolet electron spectroscopy (UPS), and band structure were used. This study aims to improve photocatalytic performance by designing and constructing ohmic heterojunctions, and provides a new design approach for improving photocatalytic performance.

Amine-rich cyclotriphosphazene (P3N3) nano-cages for enhanced and selective Au(III) and Pd(II) recovery and hydrogen generation: Waste-to-resource tactics

Designing a new material for precious metals (PMs) recovery is of ultimate significance in the quest to explore highly efficient, selective, and stable adsorbents for a sustainable economy and green environment. Herein, novel amine-rich cyclotriphosphazene poly(tetrakis(4-aminophenyl)methane-co-cylotriphosphazene)- porous nano-cages (PTC-PNC) and microspheres (PTC-MS) were synthesized for adsorption and selective recovery of Au(III) and Pd(II) in aqueous solution. A combination of the abundant amine groups and the cage-like porous morphology of PTC-PNC makes it an ideal absorbent for recovery of the Au(III) (1592 mg g−1, pH 1.0, 60 oC) and Pd(II) (1372 mg g−1, pH 1.0, 60 oC) with high selectivity which was slightly decreased up to 8-11% even in the presence of 13 co-existing metals ions while an ultra-high recovery of 99% was obtained. The unique cage-like morphology of the PTC-PNC guarantees a fast adsorption equilibrium while the adsorption isotherm specifies a pseudo-second-order kinetic behavior and Langmuir isotherm. Amine groups were the most energetically favorable sites for the capturing and chelating of Au(III) and Pd(II) ions followed by their partial reduction to Au0 and Pd0. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron spectroscopy (HRTEM) analysis were employed to explore interactions and reduction mechanisms during the adsorption process. Adopting the waste-to-resource approach, after Au(III) and Pd(II) recovery, these adsorbents were applied for catalytic hydrogen generation from ammonia borane (AB) hydrolysis. Due to its favorable electronic structure, the PTC-PNC@Pd exhibited a higher hydrogen generation than PTC-PNC@Au. The as-synthesized PTC-PNC could be employed as a promising material for other MPs' selective recovery and green energy generation applications.

Co3O4 derived ZnO: An effective electrocatalyst for oxygen evolution reaction in alkaline media

The growing accessibility of hydrogen and renewable energy sources has led to a rising significance of cobalt oxide (Co3O4)-based electrocatalysts in the context of effective electrochemical water splitting. Among two-half cell reactions, oxygen evolution reaction (OER) is more complicated and sluggish in behaviour. We present a composite material based on cobalt oxide-derived zinc oxide (Co3O4@ZnO) prepared through a wet chemical technique to overcome this challenge. The as-prepared materials are analyzed for crystallinity, morphology, and chemical bonding through X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), high resolution transmission electron spectroscopy (HRTEM), and Fourier transform infrared (FTIR) spectroscopy, respectively. The optimized electrocatalyst reveals higher electrochemical performance for OER with an overpotential value of 262 mV at 10 mA/cm2 current density, Tafel slope value of 59 mV/dec, and charge transfer resistance (Rct) of 72 Ω. Moreover, the electrochemical active surface area (ECSA) is calculated as 320 cm2. Notably, the desired electrocatalyst shows the stability of 50 h at 10 and 20 mA/cm2 current densities. The as-prepared catalyst (Co3O4@ZnO) with effective electrochemical features can be a potential candidate for energy conversion applications toward a sustainable society.

Co-gasification of lignite and spent tea waste for the generation of hydrogen-rich syngas in a fluidized bed gasifier

The co-gasification of high moisture and high volatile content low-rank lignite (LG) coal and a common waste generated from the brewed tea leaves was studied in a fluidized bed gasification unit. Multiple experiments were conducted at different temperatures, ranging from 800 °C to 900 °C, at fixed operating parameters to elucidate the catalytic thermo-chemical impact on the gasifier performance parameters. The catalytic effect of alkali and alkaline earth metals (AAEMs), especially CaO, K2O, and Na2O present in the spent tea waste (STW) sample, on the product gas composition and performance parameters during the co-gasification experiments with LG was demonstrated. Mixed blends of LG and STW showed enhancement in the overall reactivity of the steam gasification runs, compared to the LG-only feed, primarily due to the change in the surface morphology, textures, and pore structures of the solid product ash samples, as identified with the electron spectroscopy analysis. Liquid and product samples were analyzed using characterization techniques such as Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) analytical techniques, along with the proximate, ultimate, and X-ray fluorescence (XRF) analysis of the gasification feed samples. An optimized blend ratio of 20 wt % of STW with LG sample enhanced the volumetric gas composition of H2 and CH4 gases from 52.03 % to 61.32 % and 3.98 %–5.45 % (on a dry-N2-free basis) with a relatively constant CO gas composition. It showed a reduced CO2 composition from 28.64 % to 18.25 % (on a dry-N2-free basis) for the gasification temperature of 900 °C. Even at the lower gasification temperatures of 800 °C and 850 °C with LG + STW feed, steam gasification experiments showed relatively comparable or superior performance to gasification experiments at 900 °C with LG-only feed. The present study indicated a holistic way to utilize the spent tea waste generated from millions of homes and commercial establishments in various parts of the world with potential application towards synergistic gasification process with other conventional carbon-source materials.

Engineering shallow and deep level defects in κ-Ga2O3 thin films: comparing metal-organic vapour phase epitaxy to molecular beam epitaxy and the effect of annealing treatments

Orthorhombic gallium oxide (κ-Ga2O3) is an ultra-wide bandgap semiconductor with great potential in new generation electronics. Its application is hindered at present by the limited physical understanding of the relationship between synthesis and functional properties. This work discusses the effects of growth method (metal-organic vapour phase epitaxy and molecular beam epitaxy) as well as annealing treatments in different atmospheres (O2, H2) on point defects in κ-Ga2O3 layers epitaxially grown on c-plane sapphire. Comprehensive experimental characterization by X-ray diffraction, photo current- as well as photoluminescence excitation spectroscopy, and X-ray photo electron spectroscopy is combined with first principles calculations of the point defects’ formation and complex-dissociation energies. We demonstrate that for κ-Ga2O3 the concentration of shallow and deep level defects can be sensitively controlled through annealing treatments at temperatures (T = 500 °C) well below the thermal stability threshold of this polymorph. In particular, our results suggest that hydrogen-related defects (e.g., H-interstitials, Ga-vacancies—H complexes) play a key role in this process. While we provide direct exemplary implications of our results for the performances of κ-Ga2O3 based photodetectors, these findings are predicted to impact further application fields of κ-Ga2O3, such as high electron mobility transistors or memory devices.

Synthesis, Crystal Structure, Hirshfeld Surface, Energy Frame Work and DFT Analysis of Ethyl-4-aminobenzoate Oxalate Monohydrate Salt

Using the single crystal X-ray diffraction method, the title molecule ethyl-4-aminobenzoate oxalate monohydrate has been synthesized, crystallized and characterized. The Hirshfeld surfaces computational approach was used to analyze the intermolecular interactions in the crystal structure. The aforementioned compound crystallizes in a monoclinic crystal system of space group P21/c with the following cell parameters: a = 15.475(3), b = 5.7117(9), c = 14.029(3), = 101.764(6)º, V = 1214.0(4) 3 and Z = 4. The molecules in the crystal structure are connected by the N1-H1C···O7, O5-H2···O3, O7-H1···O4 and C8-H8A···Cg type intermolecular interaction, where Cg is the centroid of the ring. For the title molecule, the inter contact O···H (48.4%) contributes more to the Hirshfeld surfaces. The proton transfer from oxalic acid’s phenolic group to ethyl-4-aminobenzoate’s amine group, which results in the creation of salt, is revealed by the crystal structure. The ground state of ethyl-4-aminobenzoate oxalate monohydrate was also studied theoretically using the density functional method (DFT/B3LYP) with a basis set of 6–311++G(d,p). Charge transfer happens within the molecule, as shown by the computed HOMO and LUMO energies, DOS and MESP, as well as by the optimized molecular structure, electronic structural analysis and UV spectrum analysis.

Origins and Importance of Intragranular Cracking in Layered Lithium Transition Metal Oxide Cathodes.

Li-ion batteries have a pivotal role in the transition toward electric transportation. Ni-rich layered transition metal oxide (LTMO) cathode materials promise high specific capacity and lower cost but exhibit faster degradation compared with lower Ni alternatives. Here, we employ high-resolution electron microscopy and spectroscopy techniques to investigate the nanoscale origins and impact on performance of intragranular cracking (within primary crystals) in Ni-rich LTMOs. We find that intragranular cracking is widespread in charged specimens early in cycle life but uncommon in discharged samples even after cycling. The distribution of intragranular cracking is highly inhomogeneous. We conclude that intragranular cracking is caused by local stresses that can have several independent sources: neighboring particle anisotropic expansion/contraction, Li- and TM-inhomogeneities at the primary and secondary particle levels, and interfacing of electrochemically active and inactive phases. Our results suggest that intragranular cracks can manifest at different points of life of the cathode and can potentially lead to capacity fade and impedance rise of LTMO cathodes through plane gliding and particle detachment that lead to exposure of additional surfaces to the electrolyte and loss of electrical contact.

Study on modified graphene oxide-based emulsion cleaner for oily sludge

Abstract Oily sludge is a complex system that is inevitably generated during the process of oil extracting and processing. It will cause serious environmental pollution and waste of resources if untreated sludge is discharged. In this paper, a composite emulsion cleaner based on modified graphite oxide and surfactants was developed for cleaning oily sludge. First, graphite oxide (GO) was functionally modified with butylamine, and its structures were verified by Fourier transform infrared spectroscopy (FTIR), X-ray electron spectroscopy (XPS), thermogravimetric analysis (TGA), and environmental scanning electron microscopy (SEM). Then, the oil-in-water composite emulsion cleaner was prepared by using butylamine modified graphite oxide and surfactants. The conditions for emulsion preparation and oil sludge cleaning were modelled and optimized by the response surface methodology. The obtained optimal formulations were: surfactant content was 2.17 ‰ with SDS/AEO-3 ratio of 9:1, GO-A4 content was 0.96 ‰, water-oil ratio was 5:5, and the oil removal rate was 97.45 %. The optimal cleaning conditions were: liquid-solid ratio of 3.2:1, cleaning time of 32 min, cleaning temperature of 28.7 °C, and oil removal rate of 99.02 %. The solid sediments were characterized by FTIR and SEM, which proved the feasibility of cleaning oily sludge with the emulsion.