Electron Spectroscopy Methods Research Articles

Electrocatalytic efficiency of carbon nitride supported gold nanoparticle based sensor for iodide and cysteine detection

Extensive investigations are being conducted on gold nanoparticles focusing on their applications in biosensors, laser phototherapy, targeted drug delivery and bioimaging utilizing advanced detection techniques. In this work, an electrochemical sensor was developed based on graphite carbon nitride supported gold nanoparticles. Carbon nitride supported gold nanoparticles (Au–CN) was synthesized by applying a deposition-precipitation route followed by a chemical reduction technique. The composite system was characterized by X-ray diffraction and X-ray photo electron spectroscopy methods. Electron microscopy analysis confirmed the formation of gold nanoparticles within the size range of 5–15 nm on the carbon nitride support. Carbon nitride supported gold based sensor was employed for the electrochemical detection of iodide ion and l-cysteine. The limit of detection and sensitivity of the sensor was attained 8.9 μM and 0.96 μAμM⁻1cm⁻2, respectively, for iodide ion, while 0.48 μM and 5.8 μAμM⁻1cm⁻2, respectively, was achieved for the recognition of cysteine. Furthermore, a paper-based electrochemical device was developed using the Au–CN hybrid system that exhibited promising results in detecting iodide ions, highlighting its potential for economic and portable device applications.

Analysis of the Influence of Formation of Pd Silicides on Surface Layers of Si on the Diffusion of Atoms of Contacting Metal

4-probe measurements of surface resistivity, measurements of dark and light current-voltage characteristics, the possibilities of using a thin PdSi film to obtain perfect nano-sized ohmic contacts on the Si(111) surface have been investigated using Auger electron spectroscopy methods in combination with ion etching of the surface. It has been shown that the depth of Ni diffusion in the Ni-Si (111) system is 400 ‑ 500 Å at indoor temperature, and 70 – 80 Å in the Ni-PdSi-Si (111) system. The quality of the ohmic contact in the latter case does not change up to T = 800 K and withstands luminous flux illumination up to F = 1100 lux. It is shown that the resistivity of the PdSi film passes through a minimum at T = 900 – 1000 K. An analysis of the results obtained will be given in the article.

Cross-Sectional Preparation of Complex Energy Devices and Their Characterization By Advanced Microscopic Methods

Energy devices such as batteries, fuel cells, and solar cells are composed of multiple functional components with varying material properties. Achieving a fundamental understanding of structure-property relationships and systematically enhancing performance, while also investigating device degradation and failure mechanisms, requires high-quality cross-sections of entire devices or substantial regions. Given that many devices contain different classes of materials, including liquid and/or air-sensitive components, working under cryogenic or inert conditions is necessary to maintain their original state. To facilitate cross-sectional characterization of these devices from the macroscopic down to the atomic level, we use a range of preparation tools. A self-designed cryo-cutter allows us to efficiently produce cross-sections of entire devices, such as pouch cells, in a single step, enabling optical microscopy (OM) observation at the centimeter scale while preserving their pristine state. For finer scales, cryo-ultramicrotomy and focused ion beam (FIB) techniques are regularly employed. These methods can prepare high-quality thin samples under 50 nm for investigations using OM, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) at atomic resolution. In this presentation, we demonstrate the scale-bridging capabilities of these preparation techniques applied to various devices and their components in conjunction with advanced electron microscopic and spectroscopic methods. Examples include devices such as batteries (Fig. 1) and complex proton exchange membrane (PEM) fuel cells, as well as battery components (Fig. 2). The techniques used are ideal for assessing the integrity of entire devices and the interfaces of individual layers and components, including their morphology, contact, composition, and chemical bonding states. Acknowledgement: Part of this work was performed at the Micro-and Nanoanalytics Facility (MNaF) of the University of Siegen. Figure 1

Formation of thin Crsi2 films by the solid-phase ion-plasma method and their thermoelectric properties

ABSTRACT CrSi2 thin films with different thicknesses obtained on the Si(111) surface by magnetron sputtering method have been investigated using complex of electron spectroscopy and microscopy methods. The thin films’ composition, surface morphology, and cross-section, as well as the resistivity’s, Seebeck coefficient’s, and power factor’s temperature dependences have been studied for the first time. It has been established that, starting from a thickness of ~ 400 Å (deposition time ~ 60 sec), the SiO2/Si(111) surface is completely covered with an amorphous CrSi2 film. After heating the CrSi2/SiO2/Si(111) system at T ≈ 750 K, a homogeneous polycrystalline CrSi2/SiO2/Si(111) film is formed. It is shown that the resistivity ρ, the Seebeck coefficient S, and the power factor P of a CrSi2/SiO2/Si(111) film of different thicknesses (80 and 180 nm) change nonlinearly with increasing temperature. Their values for CrSi2 films of different thicknesses differ slightly from each other.

Mechanical characterization of materials using advanced microscopy techniques

This review explores the synergistic relationship between advanced microscopy techniques and mechanical engineering, outlining their profound impact on materials science and mechanical system design. We delve into the multifaceted applications of electron microscopy, X-ray diffraction, and spectroscopic methods in understanding microstructural dynamics, mechanical properties, and failure mechanisms of materials integral to mechanical engineering. Through a comprehensive synthesis of recent research, we emphasize the pivotal role these techniques play in optimizing material performance, bolstering structural integrity, and driving innovation in mechanical design. By elucidating the intricate details of material behavior at the microscale, advanced microscopy contributes to informed decision-making in material selection and design processes. Furthermore, we address emerging trends and prospects, underscoring the continued synergy between advanced microscopy and mechanical engineering. This collaboration remains at the forefront of materials science and technology, promising ongoing advancements that will shape the future landscape of mechanical design and materials innovation.

Using Graphdiyne Nanoribbons for Molecular Electronics Spectroscopy and Nucleobase Identification: A Theoretical Investigation.

In pursuit of fast, cost-effective, and reliable DNA sequencing techniques, a variety of two-dimensional (2D) material-based nanodevices such as solid-state nanopores and nanochannels have been explored and established. Given the promising potential of graphene for the design and fabrication of nanobiosensors, other 2D carbon allotropes such as graphyne and graphdiyne have also attracted a great deal of attention as candidate materials for the development of sequencing technology. Herein, employing the 2D electronic molecular spectroscopy (2DMES) method, we investigate the capability of graphdiyne nanoribbons (GDNRs) as the building blocks of a feasible, precise, and ultrafast sequencing device. Using first-principles calculations, we study the adsorption of four canonical nucleobases (NBs), i.e., adenine (A), cytosine (C), guanine (G), and thymine (T) on an armchair GDNR (AGDNR). Our calculations reveal that compared to graphene, graphdiyne demonstrates more distinct binding energies for different NBs, indicating its more promising ability to unambiguously recognize DNA bases. Utilizing the 2DMES technique, we calculate the differential conductance (Δg) of the studied NB-AGDNR systems and show that the resulting Δg maps, unique for each NB-AGDNR complex, can be used to recognize each individual NB without ambiguity. We also investigate the conductance sensitivity of the proposed nanobiosensor and show that it exhibits high sensitivity and selectivity toward various NBs. Thus, our proposed graphdiyne-based nanodevice would hold promise for next-generation DNA sequencing technology.

Fabrication of g-C3N4 decorated Au/Zn3(PO4)2 composites for remarkable H2 production under visible-light irradiation

In the present study, novel gold nanoparticles (Au NPs) loaded Zinc phosphate (Zn3(PO4)2)/graphitic carbon nitride (g-C3N4) nanocomposites were fabricated via a facile hydrothermal routes followed by calcination. Surfactants and capping agents were not required for this method. After the samples had been produced, they were examined using a number of electron microscopy and spectroscopic methods. The data showed that the spherical Zn3(PO4)2 particles that were coated on the g-C3N4 nanosheets had a good distribution of Au nanoparticles (NPs) on their surfaces. In comparison to Zn3(PO4)2 (461 μmol−1 h−1 of H2) and g-C3N4 (171 μmol−1 h−1 of H2), the optimized composite, 0.5 wt% Au/Zn3(PO4)2-gC3N4 (95–5), showed a remarkable production rate under visible light (1241 μmol−1 h−1 of H2). The highest performing composite was characterized using UV–visible, X-ray photoelectron spectra (XPS), Transmission electron microscope (TEM), N2 adsorption-desorption, time dependent photo-current study and Current-density–potential studies. Several events were identified as contributing to the photocatalyst's performance; for example, the effective heterojunction formation between g-C3N4 and Zn3(PO4)2 under Z-scheme dynamics led to visible-light photosensitization; new electronic hybrid states of the semiconductor band energies resulted from the porosity size and shape; and the Au NPs exhibited electronic trappingsites and co-catalytic effects. These enhancements to light harvesting and charge carrier separation allowed for greater activity to be powered by visible light.

The influence of implantation of Mg+ ions and subsequent annealing on the composition, electronic structures, emission and optical properties of CdF2

Relevance. In the case of bombardment with Mg metal ions, the changes are accompanied by the introduction of metal atoms and the formation of various types of compounds. Thus, CdF2 is intensively decomposed into components in the near-surface layer in the process of ion implantation. A small part of these components can be sprayed from the surface. Due to the high chemical activity, almost all of the liberated fluorine atoms again enter into a chemical bond with both the atoms of the alloying element and the atoms of cadmium. Consequently, three-component compounds are formed in the near-surface layer. Therefore, it is necessary to define the electronic states, band energy, and optical parameters of CdF2 and Cd0.6Mg0.4F2 films. Purpose. The composition, structure, and properties of CdF2 implanted with Mg+ ions in combination with thermal and laser annealing for the first time were the research aims. Methodology. The experimental studies were carried out at a vacuum of at least 10-7 Pa using the methods of Auger electron spectroscopy (AES) and ultraviolet photoelectron spectroscopy (UVES). The depth distribution profiles of atoms were determined by the AES method in combination with layer-by-layer etching of the surface with Ar+ ions with E0=2-3 keV. Results. CdF2 is intensively decomposed into components in the near-surface layer in the process of ion implantation. Consequently, three-component compounds are formed in the near-surface layer. Band-energy parameters and densities of the state of electrons in the valence band of this film are determined. Conclusions. The effect of the implantation of Mg+ ions on the composition and electronic structure of single-crystal CdF2/Si(III) films was studied for the first time. The densities of electronic states, band-energy and optical parameters of CdF2 and Cd0.6Mg0.4F2 films have been determined

Expansion of the functional capacities of electrostatic mirror analyzers for electron spectroscopy

Electron spectroscopy methods are widely used in scientific research and for technological purposes. The main element of spectrometers is an analyzer of charged particle beams. Electrostatic mirror systems are widely used due to their simpler practical realization. At their development two purposes were set: to improve the quality of spatial focusing of charged particles or to increase the value of linear energy dispersion. The objects of the study are electrostatic systems characterized by small sizes, simplicity of stabilization and localization of the working field and its shielding from the external electromagnetic disturbances. From all the known types of energy analyzers, suitable for the analysis of solid surfaces, preference is given to those that have good electron-optical properties, are simple in manufacture and operation. Therefore, spherical and cylindrical mirrors, which have become a basic tool for firms producing spectrometers, have been chosen as the object of study. The work solves the problem of expansion of the functional capacities of these systems by, firstly, combining several research methods in one device; and secondly, by solving specific narrower problems. A photoelectron or Auger spectrometer with an increased scanning area is proposed, where the initial angular opening of the beam 4° after passing a cylindrical mirror is increased to 10°, and the image smearing is reduced to 0.05 %. An Auger-electron spectrometer for analysis of rough surface has been developed, which allows to increase the probing depths by more than 5 times. A double filter type energy analyzer is calculated. Energy resolution was improved to 1.37 % by eliminating potential barrier smearing in low energy filter mode. Previously, the energy resolution was limited to 10 % due to this drawback

Determination of Layer-By-Layer Profiles of Hydrogen Isotopes in Carbon and Beryllium Based on Electron Spectroscopy Methods

Determination of Layer-By-Layer Profiles of Hydrogen Isotopes in Carbon and Beryllium Based on Electron Spectroscopy Methods

Determination of Layer-By-Layer Profiles of Hydrogen Isotopes in Carbon and Beryllium Based on Electron Spectroscopy Methods

A quantitative method for interpreting the spectroscopy signal of elastically reflected electron peaks is constructed taking into account the layer-by-layer analysis of the content of hydrogen isotopes in structural materials used in the international experimental thermonuclear reactor ITER under construction. The relative protium and deuterium concentrations in hydrocarbon samples are determined. The relative deuterium concentrations in a beryllium sample are determined.

Atomic structure and electronic properties of Ce + O films co-adsorbed on Mo(112)

The atomic structure, stoichiometry and electron work function of Ce + O films co-adsorbed on Mo(112) were studied by low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and contact potential difference (CPD) methods. The films with a significant predominance of one major species show the structure characteristic of the main component, which remains stable up to 15−50% of the minor species content. We report the c(4 × 4) and c(2 × 6) superstructures for Ce + O films with single layer Ce coverage as well as c(4 × 6) and (2 × 2) for double layer Ce coverage. They are exclusively specific to the (Ce + O)/Mo(112) system and have not been previously observed neither for cerium oxides nor pure cerium/pure oxygen adfilms. No noticeable electron work function change was detected due to oxygen addition to the Ce/Mo(112) films. Both oxygen-enriched and oxygen-depleted (Ce + O) films show similar typical electropositive properties.

In Ukrainian

Сreation of new therapeutic materials based on nucleic acids encourages the combination of the latter with materials capable of adsorbing them. One of the most promising materials for such purposes is nanocrystalline titanium dioxide due to its low toxicity, stability of its physical and chemical parameters, and high biocompatibility. Accordingly, understanding the nature of the interaction of the surface of titanium oxide with biologically active substances is a very important issue. It is also always a relevant question whether the biopolymer immobilized on the surface of a solid remains capable of serving as a reservoir for drug delivery or a tool for the treatment of a particular disease. The aim of the work was to investigate the interaction of the biologically active substance rivanol with the surface of DNA-containing titanium dioxide. It has been found that prior adsorption of deoxyribonucleic acid on the surface of titanium dioxide does not prevent its interaction with rivanol, which was confirmed by the methods of electron spectroscopy, atomic force and scanning electron microscopy. The mode of interaction of rivanol with deoxyribonucleic acid depends on the ratio of their concentrations and can be either intercalated or semi-intercalated, and electrostatic. Based on the calculated thermodynamic characteristics, the process of interaction of deoxyribonucleic acid adsorbed on the surface of a solid carrier is arbitrary and occurs by an ion exchange mechanism. These hybrid organo-mineral sorbents can serve as model structures for research in biotechnological fields, be used for the development of new methods of drug or gene delivery, reservoir systems at a molecular level, and serve as biocompatible carriers. The creation of organo-mineral sorbents, which combine nucleic acids and metal oxides, contributes to the stabilization of such systems and expands the scope of their possible application in medicine and biotechnology, increasing their target specificity.

Structure, interaction with biomolecules, and cytotoxicity of copper (II) complexes chelating some Schiff base ligands

Cancer remains one of the most common diseases worldwide in terms of deaths and claims many lives every day. Transition metal complexes are candidates in the development of anticancer drugs, with cisplatin being used in chemotherapy worldwide. Copper, an endogenous metal, is known for its pronounced redox potential and nucleophilicity, especially when bound to biological molecules. Cu (II) complexes were synthesized containing ethane‐1,2‐diamine as amine moiety and pentane‐2,4‐dione and/or 1‐phenylbutane‐1,3‐dione, pentane‐2,4‐dione and/or 1,1,1‐trifluoropentane‐2,4‐dione or 1,1,1‐trifluoropentane‐2,4‐dione and/or 1‐phenylbutane‐1,3‐dione as β‐diketone moiety. Standard methods were used to confirm the structure of complexes 1–6. X‐ray crystal structure analysis characterized complex 1 containing the ligand ethane‐1,2‐diamine and pentane‐2,4‐dione. The interactions of complexes 1–6 with calf thymus DNA (ct‐DNA) were followed by electronic absorption and fluorescence spectroscopy methods and by viscosity measurements. In contrast, interaction with Salmon Sperm DNA was investigated using the electrophoretic mobility shift assay. The results indicate a moderate affinity of complexes 1–6 for binding to DNA. Gel electrophoresis also shows that the studied complexes have a concentration‐dependent interaction with DNA. Spectroscopic fluorescence techniques were used to monitor the affinity of the complexes for bovine serum albumin (BSA). Complexes 1–6 showed satisfactory binding ability for BSA. Cytotoxicity analyses were performed on the human colorectal carcinoma HCT‐116 and healthy lung fibroblast MRC‐5 cell lines, showing that complex 5 exhibited selectivity between cancer and normal cells, which is critical for drug development.

POLYANILINE, HALLOYSITE NANOTUBES AND THEIR NANOCOMPOSITE AS ADSORBENTS FOR ORGANIC DYES

This work is devoted to the study of the adsorption efficiency of methylene blue and methyl orange dyes by polyaniline base (PANI), halloysite nanotubes (HNTs), and their nanocomposite (HNTs/PANI). PANI and the nanocomposite were prepared by the chemical oxidative polymerization of aniline in the absence and presence of HNTs followed by subsequent dedoping by ammonia solution. The morphology and thermal stability of the adsorbents were explored. In particular, the TEM method showed that the nanocomposite consisted of practically non-agglomerated nanoparticles with a “core-shell” morphology. Particles of pure polymer are quite agglomerated and form massive aggregates. The kinetics of decreasing the concentration of dyes in solutions upon their contact with adsorbent powders was studied by the method of electron spectroscopy. The HNTs/PANI nanocomposite was found to absorb both dyes with slightly higher efficiency than the PANI base probably due to more developed surface of the former. Processing of the obtained results of adsorption of both dyes on the studied adsorbents according to different kinetic models (pseudo-first and pseudo-second order and intraparticle diffusion) showed that in all cases this process is best described by the pseudo-second order model, which indicates the chemical nature of adsorption. The calculated adsorption capacity of the adsorbents under study appeared be quite close to the experimental one. These materials can be used as effective adsorbents for cleaning wastewaters from organic dyes.

IDENTIFICATION OF TRIARYLMETHANE, PHTHALOCYANINE AND XANTHENE IN A MIXTURE OF DYES BY ELECTRON ABSORPTION SPECTROSCOPY

In the work, the qualitative composition and differentiation of 43 samples of ballpoint pen pastes of different colors was investigated (blue-violet – 29 samples, pink-violet – 3 samples, blue – 3 samples, black – 5 samples, green – 1 sample and red –2 samples) by the method of electronic absorption spectroscopy. The results of the study showed that each paste can be distinguished by studying the nature of their absorption spectra, which arises due to the presence of different functional groups. It was established that most of the analyzed paste samples contain pigments based on triarylmethane, phthalocyanine, xanthene dyes or their mixture. Certain absorption maxima correspond to each type of dyes. The broad and most intense band at λ~590 nm, which was detected for all samples, corresponds to triarylmethane dyes. The band at λ~670 nm corresponds to phthalocyanine dyes. The presence of absorption bands in the green range (λ~520–560 nm) indicates the presence of xanthene dyes in the composition of the pastes. Using the method of photoluminescence spectroscopy upon exci­tation of IR luminescence in the green region of the spectrum (λ=530 nm) it is shown that 11 blue-violet, 5 black and one red pastes exhibit bright luminescence due to the presence of crystal violet and some other triarylmethane dyes in their composition. Weak luminescence was detected for three blue pastes. No luminescence response was observed for the other tes­ted pastes, which is due to the presence of phthalocyanine dyes in these pastes, the absorption of which overlaps with the luminescence spectra of triarylmethane dyes. The obtained data can be used to create a reference base for identifying and differentiating the composition of ballpoint pen pastes of modern manufacturers and establishing their classification and identification differences.

Development of Copper Complexes with Diimines and Dipicolinate as Anticancer Cytotoxic Agents.

Coordination complexes may act as anticancer agents. Among others, the formation of the complex may facilitate the ligand uptake by the cell. Searching for new copper compounds with cytotoxic activity, the complex Cu-dipicolinate was studied as a neutral scaffold to form ternary complexes with diimines. A series of [Cu(dipicolinate)(diimine)] complexes (where diimine: Phenanthroline, phen, 5-NO2-phenanthroline, 4-methyl-phenanthroline, neocuproine, 3,4,7,8-tetramethyl-phenanthroline, tmp, bathophenanthroline, bipyridine, dimethyl-bipyridine, as well as the ligand 2,2-dipyridil-amine, bam) were synthesized and characterized both in the solid state, including a new crystal structure of [Cu2(dipicolinate)2(tmp)2]·7H2O. Their chemistry in aqueous solution was explored by UV/vis spectroscopy, conductivity, cyclic voltammetry, and electron paramagnetic resonance studies. Their DNA binding was analyzed by electronic spectroscopy (determining Kb values), circular dichroism, and viscosity methods. The cytotoxicity of the complexes was assessed on human cancer cell lines MDA-MB-231, MCF-7 (breast, the first triple negative), A549 (lung epithelial) and A2780cis (ovarian, Cisplatin-resistant), and non-tumor cell lines MRC-5 (lung) and MCF-10A (breast). The major species are ternary, in solution and solid state. Complexes are highly cytotoxic as compared to Cisplatin. Complexes containing bam and phen are interesting candidates to study their in vivo activity in triple-negative breast cancer treatment.

Model experiments with Auger electron and X-ray photoelectron spectroscopy at lithiated graphite material: Surface changes related to ion- and electron-beam effects

Li-based batteries as a key element for green energy economy should be permanently improved in their performance. Therefore, the complex electrochemical processes in such batteries have to be understood in detail. For their characterization beside (electro-)chemical methods also electron spectroscopic methods such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are used to get more insight into the chemical processes at the surfaces. One crucial point is stability of the solid electrolyte interface (SEI) upon measurements, especially at the (graphite-)anodes. In this paper, we use highly oriented pyrolytic graphite (HOPG) as a model anode material, which was lithiated in a molten metal intercalation process. Strong beam damage effects at the lithiated HOPG under electron and ion beam radiation are observed and described. These effects are important for using of local electron beam investigations and sputter depth profiling, often applied also for SEI characterization.

Tris chelated meridional isomers of Co(III) complexes: Synthesis, crystal structure, protein binding, cytotoxicity studies and DFT/TDDFT calculation

Two mononuclear Co(III) complexes, [Co(L1)3] (1) and [Co(L2)3] (2) (HL1, 2-[(2-methoxy-ethylimino)-methyl]-phenol; HL2, 1-[(2-methoxy-ethylimino)-methyl]-naphthalen-2-ol) have been synthesized and characterized by X-ray crystal structure determination, IR and mass spectroscopic techniques. Both the complexes are mononuclear with distorted octahedral geometries and the Co(III) center are coordinated with three bidentate (O, N) Schiff base ligands. Complexes 1 and 2 form 1D and 3D supramolecular structures, respectively, with weak CH…π interactions. Experimental UV–vis absorption spectra have been compared with the results obtained from DFT / TD-DFT calculation using B3LYP functional and LanL2DZ basis set. The interaction of the complexes with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using electronic absorption and fluorescence spectroscopic methods and the results show that complexes potentially quench the fluorescence of BSA/HSA through ground state association mechanism. Cytotoxicity studies of these complexes have been performed against breast cancer cell lines and found that they have moderate anticancer activity.

Особенности фотоэлектронных спектров Ge, имплантированного ионами Na-=SUP=-+-=/SUP=-

Using the methods of Auger electron and photoelectron spectroscopy and light absorption spectroscopy, the composition, densities of state of electrons in the valence band, and parameters of the energy bands of Ge (111) implanted with Na+ ions with an energy of E0 = 0.5 keV at a dose of D = Dsat = 6·1016 cm-2 and a thin layer of NaGe2 obtained by heating ion-implanted Ge. It is shown that a narrow n-type band (~0.2 eV) appears in the Ge valence electron spectrum after ion implantation near the bottom of the conduction band, which is explained by the presence of a large number of unbound Na atoms in the ion-doped layer. NaGe2 nanofilms with a band gap of ~0.45 eV was obtained for the first time by heating ion-implanted Ge.