X-ray Photoelectron Spectroscopy Data Research Articles

Ambient pressure x-ray photoelectron spectroscopy study on the initial atomic layer deposition process of platinum

The initial adsorption of MeCpPtMe3 is investigated using synchrotron-based ambient pressure x-ray photoelectron spectroscopy (XPS). The experiments are done on a native oxide-covered Si substrate. In addition, a reaction with O2 and the created Pt surface was investigated. Inspiration for the reaction studies was found from atomic layer deposition of metallic Pt, process that uses the same compounds as precursors. With time-resolved XPS, we have been able to observe details of the deposition process and especially see chemical changes on the Pt atoms during the initial deposition of the Pt precursor. The change of the binding energy of the Pt 4f core level appears to occur on a different timescale than the growth of the active surface sites. The very long pulse of the Pt precursor resulted in a metallic surface already from the beginning, which suggest chemical vapor deposition-like reactions occurring between the surface and the precursor molecules in this experiment. Additionally, based on the XPS data measured after the Pt precursor pulse, we can make suggestions for the reaction pathway, which point toward a scenario that leaves carbon from the MeCpPtMe3 precursor on the surface. These carbon species are then efficiently removed by the subsequent coreactant pulse, leaving behind a mostly metallic Pt film.

Gradient Functionalization of Poly(lactic acid)-Based Materials with Polylysine for Spatially Controlled Cell Adhesion.

The development of biomaterials with gradient surface modification capable of spatially controlled cell adhesion and migration is of great importance for tissue engineering and regeneration. In this study, we proposed a method for the covalent modification of PLA-based materials with a cationic polypeptide (polylysine, PLys) via a thiol-ene click reaction carried out under a light gradient. With this aim, PLA-based films were fabricated and modified with 2-aminoethyl methacrylate (AEMA) as a double bond source. The latter was introduced by reacting pre-formed and activated surface carboxyl groups with the amino group of AEMA. The success of the modification was confirmed by 1H NMR, Raman and X-ray photoelectron spectroscopy data. A further photoinduced thiol-ene click reaction in the presence of a photosensitive initiator as a radical source was further optimized using cysteine. For grafting of PLys via the thiol-ene click reaction, PLys with a terminal thiol group was synthesized by ring-opening polymerization using Cys(Acm) as an amine initiator. Deprotection of the polypeptide resulted in the formation of free thiol groups of Cys-PLys. Successful gradient grafting of Cys-PLys was evidenced by covalent staining with the fluorescent dye Cy3-NHS. In addition, PLys gradient-dependent adhesion and migration of HEK 293 cells on PLys-PLA-based surfaces was confirmed.

Green synthesis of La2O3–LaPO4 nanocomposites using Charybdis natator for DNA binding, cytotoxic, catalytic, and luminescence applications

Abstract A one-step biosynthetic pathway for the fabrication of La2O3–LaPO4 nanocomposites (NCs) was developed, employing Charybdis natator. The structure and phase changes of the NCs were confirmed, and their diverse applications were explored. The peaks at 206, 332, and 442 nm in UV-DRS studies confirmed the formation of La2O3–LaPO4 NCs. Fourier transform infrared spectral analysis revealed La–O stretching at 716 cm−1 and the presence of PO 4 3 − {\text{PO}}_{4}^{3-} bands at 532, 560, 578, and 618 cm−1. X-ray diffraction patterns showed a hexagonal phase of La2O3 with peaks at 2θ 11.04 and 28.57 and monoclinic LaPO4 phases at 2θ = 18.79 and 41.88. X-ray photoelectron spectroscopy data showed binding energy peaks at 836.04 and 852.77 eV, corresponding to 3d5/2 and 3d3/2 of the lanthanum. The average particle size from HR-TEM analysis was 28.95 nm after annealing at 800°C and SAED patterns confirmed their crystalline nature. The high affinity of the NCs towards ctDNA was established by a binding constant value of 2.08 (mg·mL−1)−1. Under UV exposure, 96% degradation efficiency for methyl orange within 120 min at pH 4 was displayed, with a rate constant of 2.72 × 10−2 min−1 affirming their photocatalytic potential. Their biocompatibility was assessed through MTT assay and luminescence characteristics were evaluated.

Ensuring the Global Comparability of XPS Data Through Intensity Scale Calibration: Summary of ISO 5861:2024

ABSTRACTFor quantitative analyses of data acquired from x‐ray photoelectron spectroscopy (XPS) instruments to be globally comparable across industry and academia, a consistent and traceable intensity calibration method is required. ISO 5861 was prepared by Technical Committee ISO/TC 201 Surface Chemical Analysis, Subcommittee 7, Electron Spectroscopies, and describes an intensity calibration method for x‐ray photoelectron spectrometers that use quartz‐crystal monochromated Al Ka x‐rays. The method employs low‐density polyethylene reference spectra that are corrected for any instrument geometry and are traceable to the true reference spectra for gold, silver and copper held by the National Physical Laboratory (NPL), UK. This international standard generates a spectrometer relative response function for use in quantitative XPS analysis that is consistent with NPL's intensity calibration method to within 5% relative error.

Influence of iron content in palladium catalysts supported on alumina and their reduction conditions on the hydrodechlorination of diclofenac in aqueous solutions

Using the method of wet impregnation of alumina with iron and palladium nitrates, 1Pd0.5Fe and 1Pd10Fe catalysts modified with iron oxides were prepared with a target content of 1 wt % Pd, 0.5 or 10 wt % iron. The catalysts were compared with each other and with the monometallic catalyst 1Pd in the hydrodechlorination (HDC) of diclofenac (DCF) in dilute aqueous solutions at 30°C in batch and flow reactors after high-temperature (320°C) and mild (30°C) reduction; the latter was carried out in a batch or flow reactor. Using X-ray photoelectron spectroscopy (XPS), it was shown that after reduction at 320°C the surface of catalysts contains mainly Pd0, Fe2+ and Fe3+. The surface Fe2+/Fe3+ ratio increases as the iron content decreases. The reduction of Pd2+ to Pd0 is possible already at 30°C, but it proceeds much worse on the surface of 1Pd0.5Fe compared to 1Pd10Fe. According to XPS data, temperature-programmed reduction and infrared spectroscopy of diffuse reflection of adsorbed CO, modification with iron oxides increases the palladium content on the surface compared to 1Pd, promotes the emergence of new Pd–O–Fe centers, and affects the ability of palladium to be reduced. These effects increase with increasing iron content. Iron-modified catalysts reduced at 320°C showed similar activity and stability in the conversion of DCP in flow-through and batch systems. Unlike 1Pd0.5Fe, the 1Pd10Fe catalyst is highly efficient and stable even after mild reduction at 30°C. Under flow conditions with comparable DCF conversion, it provides increased selectivity in the HDC reaction of diclofenac compared to 1Pd, which is also active in hydrogenation.

Regulation of extracellular electron transfer by sustained existence of Fe²⁺/Fe³⁺ redox couples on iron oxide-functionalized woody biochar anode surfaces in bioelectrochemical systems

Sluggish extracellular electron transfer between the exoelectrogens and anode interface limits the application of bioelectrochemical systems (BECs) for energy generation. In this study, an innovative anode coated with oxidized biochar and co-functionalized with iron nanoparticles (FBC/Fe2O3) was developed to enhance microbial reactions through tuned physicochemical and electrical properties. The designed anode features a highly porous, heterogeneous structure with a large accessible surface area of 10.141 m²/g, promoting better habitation and metabolism of exoelectrogens. The synergistic effect of iron nanoparticles and oxidized functional groups increased the hydrophilicity of the anode surface, augmenting its affinity for bacterial outer membrane c-cysts and facilitating microbial adhesion at a density of 3.106 × 10⁹ CFU/cm². The iron moieties on the FBC/Fe2O3 electrode surface act as electron mediators, utilizing Fe²⁺/Fe³⁺ redox couples, as evidenced by X-ray photoelectron spectroscopy (XPS) data. This enhancement improved extracellular electron transfer (EET) between bacterial cells and the anode surface, resulting in a faster and bifurcated EET process through both direct transfer via outer membrane c-cysts and mediated transfer via the redox couples of Fe moieties. The assembled double-chamber microbial fuel cell (DC-MFC) with the FBC/Fe2O3 anode achieved a maximum power density of 528.75 mW/m² and a chemical oxygen demand (COD) removal efficiency of 47.5 % within 24 h of operation.

Benchmark Study of Core-Ionization Energies with the Generalized Active Space-Driven Similarity Renormalization Group.

X-ray photoelectron spectroscopy (XPS) is a powerful experimental technique for probing the electronic structure of molecules and materials; however, interpreting XPS data requires accurate computational methods to model core-ionized states. This work proposes and benchmarks a new approach based on the generalized active space-driven similarity renormalization group (GAS-DSRG) for calculating core-ionization energies and treating correlation effects at the perturbative and nonperturbative levels. We tested the GAS-DSRG across three data sets. First, the vertical core-ionization energies of small molecules containing first-row elements are evaluated. GAS-DSRG achieves mean absolute errors below 0.3 eV, which is comparable to high-level coupled cluster methods. Next, the accuracy of GAS-DSRG is evaluated for larger organic molecules using the CORE65 data set, with the DSRG-MRPT3 level yielding a mean absolute error of only 0.34 eV for 65 core-ionization transitions. Insights are provided into the treatment of static and dynamic correlation, the importance of high-order perturbation theory, and notable differences from density functional theory in the predicted energy ordering of core-ionized states for specific molecules. Finally, vibrationally resolved XPS spectra of diatomic molecules (CO, N2, and O2) are simulated, showing excellent agreement with experimental data.

Surface chemistry and catalytic activity in H2O2 decomposition of pyrolytically fluoralkylated activated carbons.

According to the proposed pyrolytic method, granular activated carbon (AC) Norit 830 W was functionalized by thermal treatment of AC in hydrofluorocarbon (HFC) gases, pentafluoroethane and 1,1,1,2-tetrafluoroethane, at 400-800 °C. This method does not require activation by plasma and photons. Chemical and elemental analysis showed that the pyrolytic treatment provides a loading of 2.95 mmol (5.6 wt%) of fluorine per gram of AC. Nitrogen adsorption measurements indicated that the microporous structure contracted when AC was treated with HFC at temperatures above 400 °C. Thermogravimetry, Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR), and X-ray photoelectron spectroscopy (XPS) demonstrated the evolution of oxygen-containing and fluorine-containing groups to more thermostable groups with treatment temperature. The fluorine-containing groups grafted at high temperature, above 600 °C exhibited the highest thermal stability up to 1250 °C in dry argon. From the data of XPS and solid-state 19F nuclear magnetic resonance spectroscopy data, the grafted fluorine exists in several types of grafted F-containing groups, the HFC residues. By changing the thermal regime of fluorination, the composition of fluorine-containing groups on a carbon surface can be regulated. Isolated fluoroalkyl groups can be grafted at temperatures of 400-500 °C, while at 600 °C and above, the semi-ionic fluorine groups increase significantly. The hydrophobized surface demonstrated the ability to effectively decompose H2O2 in methanol solutions.

Dissolution of EAF slag minerals in aqueous media: Effects of sonication on brownmillerite and gehlenite

The accumulation of electric arc furnace slag (EAFS) in landfills has been causing severe environmental problems. This study examines the dissolution properties of EAFS minerals, including brownmillerite and gehlenite, essential for their possible use in resource recovery. An investigation was conducted to compare the effects of sonication and stirring on mineral dissolution while also assessing the usage of citrate as a complexing agent for gehlenite. Synthetic brownmillerite and gehlenite minerals were dissolved in aqueous solutions at room temperature using a 1:100 g/ml ratio. The dissolved elements were measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), while zeta potential and X-ray Photoelectron Spectroscopy (XPS) were used to assess changes in surface chemistry. Brownmillerite had significant dissolution extents, with Al and Ca dissolving up to 16 % and 8 %, respectively, in contrast to gehlenite, which dissolved less than 2 % under similar conditions. Sonication significantly increased the dissolution of brownmillerite by up to 100 %, although its impact on gehlenite dissolution varied depending on the duration of time. Besides, adding citrate enhanced the leaching of Al and Ca from gehlenite by facilitating complexation. XPS data demonstrated differences in elemental ratios on brownmillerite and gehlenite surfaces affected by the method used and the presence of citrate. Lastly, the dissolution extents of Al and Ca from EAFS were up to 12 %, depending on time and mixing method, with a preference for sonication over stirring. In conclusion, this study showed that minerals in EAFS have distinct dissolution characteristics, and sonication and citrate can considerably enhance dissolution.

Effects of different valence of starting oxides on the structure and properties of Co-Mn-Fe-Zn-Ni-O high-entropy ceramics

In this work, using different manganese sources, Co-Mn-Fe-Zn-Ni-O high-entropy ceramics (HECs) were synthesized via the solid-phase method. X-ray diffraction (XRD) data showed that the HECs consist of rock salt and spinel phases, and the choice of raw materials has a great influence on the phase composition and lattice distortion of HECs. Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analyses showed that the HECs have dense microstructures, with the major elements conforming to iso-atomic ratios. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy data showed that Mn3+ ions with Jahn-Teller effects distort the [MnO6] octahedra, affecting the electrical properties and aging stability of the material. The room-temperature resistivity of the HEC systems ranged from 20.81 kΩ cm to 35.43 kΩ cm, and the B25/50 resistivity values varied between 4037 K and 4048 K. The resistance drift was observed to be less than 0.70 % after aging at 125 °C for 1000 h. Impedance analyses suggested that the electrical properties of the high-entropy ceramics can be modulated by tailoring the grain size and grain boundary morphology. Selecting suitable raw materials based on valence-induced effects and the tendency of ions to occupy specific sites offers new insights into the design and synthesis of tailor-made high-entropy NTC ceramics.

Effect of substitution on corrosion inhibition properties of 4-(substituted fluoro, chloro, and amino) Benzophenone derivatives on mild steel in acidic medium: A combined Electrochemical, surface characterization and theoretical approach

Background: In this study, three mono-substituted Benzophenone (BP) derivatives, 4-Fluorobenzophenone (4-F.BP), 4-Chlorobenzophenone (4-C.BP), and 4-Aminobenzophenone (4-A.BP) were investigated using a combined electrochemical, surface characterization and theoretical approach. Methods: In experiment, the effectiveness of 4-F.BP, 4-C.BP, and 4-A.BP in inhibiting mild steel corrosion in a 1 N HCl solution were investigated using gravimetric measurements at several temperatures (303–333 K), electrochemical measurements (Potentiodynamic Polarization (PDP), and Electrochemical Impedance Spectroscopy (EIS)), UV–visible analysis, Surface morphology test (SEM and EDAX analysis, AFM analysis, water contact angle measurement, XPS analysis) as well as theoretical studies. Significant findings: Increase in the inhibitor concentrations (160, 200, 240 and 280 ppm) exhibited a maximum percentage of inhibition efficiency (IE %) of 83.75 %, 88.75 %, and 93.75 % for 280 ppm of 4-F.BP, 4-C.BP, and 4-A.BP respectively at 303 K. However, with increase in the temperature from 303 to 333 K, IE % furthermore reduced to 52.41 %, 57.24 %, and 66.20 % at 333 K. The potentiodynamic polarization plots revealed that all molecules acted as mixed-type corrosion inhibitors and had an exceptional ability to inhibit the anodic reaction. Moreover, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), and Contact angle measurement (CAM) confirms the formation of protective layer on the metal surface by the chosen inhibitors. The X-ray Photoelectron Spectroscopy (XPS) data confirms the bonding interaction between the functional groups and the metal surface. Furthermore, Density Functional Theory (DFT) calculation and Molecular Dynamics simulations (MD) were carried out to understand inhibition's molecular/atomic mechanisms. In summary, the suggested benzophenone derivatives are effective and economical anticorrosion agents for mild steel surfaces exposed to aggressive environments.

MP2-Based Composite Extrapolation Schemes Can Predict Core-Ionization Energies for First-Row Elements with Coupled-Cluster Level Accuracy.

X-ray photoelectron spectroscopy (XPS) measures core-electron binding energies (CEBEs) to reveal element-specific insights into the chemical environment and bonding. Accurate theoretical CEBE prediction aids XPS interpretation but requires proper modeling of orbital relaxation and electron correlation upon core-ionization. This work systematically investigates basis set selection for extrapolation to the complete basis set limit of CEBEs from ΔMP2 and ΔCC energies across 94 K-edges in diverse organic molecules. We demonstrate that an alternative composite scheme using ΔMP2 in a large basis corrected by ΔCC-ΔMP2 difference in a small basis can quantitatively recover optimally extrapolated ΔCC CEBEs within 0.02 eV. Unlike ΔCC, MP2 calculations do not suffer from convergence issues and are computationally cheaper, and thus, the composite ΔMP2/ΔCC scheme balances accuracy and cost, overcoming limitations of solely using either method. We conclude by providing a comprehensive analysis of the choice of small and large basis sets for the composite schemes and provide practical recommendations for highly accurate (within 0.10-0.15 eV MAE) ab initio prediction of XPS data.

Ionic Liquids as Extreme Pressure Additives for Bearing Steel Applications

The protection of steel surfaces from wear under extreme pressure conditions is of major importance in several industries as it provides better performance and longer life of machinery. The motivation for this work was to study the lubrication of steel by ionic liquids (ILs), which have recently emerged as greener alternatives to commercial lubricants and additives. Three ILs based on sulfur-containing anions, used as 2-wt% additives in polyethylene glycol base oil (MW 200; PEG 200), were tested in the lubrication of ASTM 52100 bearing steel contacts in extreme pressure conditions (under mixed lubrication with a Hertzian pressure of 1.12 GPa) using a mini traction machine (MTM). Due to the poor resistance to corrosion of bearing steel, a semi-ester of succinic acid derivative corrosion inhibitor (Lanxess RC 4801) was added to the mixtures at a 1 wt% concentration. The ILs 1-hexyl-methylimidazolium trifluoromethanesulfonate ([C6mim][TfO]) and 1-hexyl-4-picolinium trifluoromethanesulfonate ([C6-4-pic][TfO]) revealed promising results in terms of surface protection of bearing steel. In contrast, 4-picolinium hydrogen sulfate ([4-picH][HSO4]) as 2-wt% additive to PEG 200 + 1% RC 4801 did not show any improvement in wear performance compared to neat PEG 200 + 1% RC 4801. PEG 200 + 2% [C6mim][TfO] + 1%RC 4801 allowed for a decrease in wear up to ~ 76% and PEG 200 + 2% [C6-4-pic][TfO] + 1%RC 4801 up to ~ 46% when compared with neat PEG 200 + 1% RC 4801. Optical microscopy images suggest the formation of an adsorbed layer, which was further supported by chemical analysis via x-ray photoelectron spectroscopy (XPS) data for [C6mim][TfO].Graphical abstract

Effect of morphology modulation and interface engineering of SnS-MoS2 heterojunction on nonlinear optical response

MoS2 base films with different morphologies were prepared by modulating the magnetron sputtering parameters, and the base films were used to induce the growth of SnS with different structures, forming columnar and worm-like SnS-MoS2 heterojunctions, which were found to have excellent nonlinear absorption properties and their properties could be modulated by the morphology of the films by Z-scanning tests. The tunable morphology and crystalline quality of the films were characterized using scanning electron microscopy, atomic force microscopy and X-ray diffraction techniques and explained using the Stranski-Krastanow growth mechanism. The Raman spectrum of the heterojunction shows the A1g vibrational peak at 320 cm−1 and the appearance of Sn4+ in the X-ray photoelectron spectroscopy confirms the existence of S-Sn-S charge transfer channels between the interfaces. The fine spectra of all the elements in the X-ray photoelectron spectroscopy data as well as the characteristic absorption peaks in the absorption spectra confirm the formation of heterojunctions, and the constructed heterojunctions are determined to be type-II heterojunctions using the method of the core energy level. Heterojunction was determined to be a type-II heterojunction by using the core energy level method. The photoluminescence peak quenching of the heterojunction indicates that there is a process of charge transfer between the interfaces, and the type-II heterostructure of SnS-MoS2 makes the nonlinear absorption performance in the 800 nm band regulated by the morphology of the material. The nonlinear optical absorption coefficient is two orders of magnitude higher than that of the pure materials, and the nonlinear absorption performance of the worm-like SnS-MoS2 heterojunction is superior to that of the columnar SnS-MoS2 heterojunction, which is attributed to the larger interfacial contact area, the better crystalline quality, and the more efficient carrier interfacial transport capability. These tunable type-II SnS-MoS2 heterojunctions with ultrafast nonlinear optical absorption have a positive impact on practical applications such as optical limiter devices and all-optical switching devices.

Tunable Hydrogen-Related Defects in ZnO Nanowires Using Oxygen Plasma Treatment by Ion Energy Adjustment.

The chemical bath deposition (CBD) process enables the deposition of ZnO nanowires (NWs) on various substrates with customizable morphology. However, the hydrogen-rich CBD environment introduces numerous hydrogen-related defects, unintentionally doping the ZnO NWs and increasing their electrical conductivity. The oxygen-based plasma treatment can modify the nature and amount of these defects, potentially tailoring the ZnO NW properties for specific applications. This study examines the impact of the average ion energy on the formation of oxygen vacancies (VO) and hydrogen-related defects in ZnO NWs exposed to low-pressure oxygen plasma. Using X-ray photoelectron spectroscopy (XPS), 5 K cathodoluminescence (5K CL), and Raman spectroscopy, a comprehensive understanding of the effect of the oxygen ion energy on the formation of defects and defect complexes was established. A series of associative and dissociative reactions indicated that controlling plasma process parameters, particularly ion energy, is crucial. The XPS data suggested that increasing the ion energy could enhance Fermi level pinning by increasing the amount of VO and favoring the hydroxyl group adsorption, expanding the depletion region of charge carriers. The 5K CL and Raman spectroscopy further demonstrated the potential to adjust the ZnO NW physical properties by varying the oxygen ion energy, affecting various donor- and acceptor-type defect complexes. This study highlights the ability to tune the ZnO NW properties at low temperature by modifying plasma process parameters, offering new possibilities for a wide variety of nanoscale engineering devices fabricated on flexible and/or transparent substrates.

3D-printed nanocomposites filled with untreated and surface-modified PTFE powders treated by a Na-naphthalene-system

This study focuses on the mechanical properties of DLP/LCD-type 3D-printed nanocomposites comprised of polyester acrylate resin with DPGDA reactive diluent filled with untreated PTFE and surface-modified PTFE powders by the Na-Naphtalenide system. To obtain the nanocomposites, untreated and surface-modified PTFE powders were incorporated into the resin systems at loading ratios ranging from 1% to 6%. The X-ray photoelectron spectroscopy (XPS) data following the Na-naphthalene system treatment demonstrated the existence of functional groups such as OH, carbonyl, and C=C unsaturation groups on the surface of the untreated PTFE powders. The study showed improvements for the nanocomposites obtained through a DLP/LCD type 3D printer up to a certain ratio in terms of tensile strength, Young's modulus, Izod impact resistance, and Shore D hardness values. Evaluating the promising samples, the nanocomposites with surface-modified PTFE powders of 2% and 1% showed increases of 5.1% and 7.6% in ultimate tensile strength and Izod impact resistance compared to the unfilled polyester acrylate sample. On the other hand, the nanocomposite with untreated PTFE powders of 1% only showed increases of 2.4% and 3.2% in ultimate tensile strength and Izod impact resistance. Moreover, Young’s modulus showed less decrease for surface-modified PTFE-filled nanocomposites.

Synergetic Effect of Chemical Components in a Tungsten CMP Slurry and the Evolution of Tungsten Surface Species

A novel slurry containing 50 ppm Fe3+, 2 wt% H2O2, 75 ppm oxalic acid, and abrasive nano-silica particles were utilized in a W chemical mechanical planarization process. Using this slurry, a W material removal rate of 710 Å min−1 and surface roughness of 1 nm were achieved. According to X-ray photoelectron spectroscopy data, surface W was first transformed to WO2 via its dissolution in H2O2, and then Fe3+ ions serving as a catalyst promoted the conversion of tungsten to WO3 through the WO2 intermediate in the presence of H2O2. Oxalic acid was added to coordinate with H2O2 and thus improve the slurry stability through a “wrapping” mechanism without decreasing the W material removal rate. Scanning electron microscopy and atomic force microscopy observations revealed that the W surface morphology changed first from coarse elongated grains to a discontinuous structure after the uneven oxidation by H2O2 and then to a wrinkled soft surface by Fe3+ and H2O2. Finally, it was ground with abrasive nano-silica particles to achieve a high degree of flatness.

Reassessment of the Shirley and model functions within X-ray photoelectron spectroscopy analysis utilizing comprehensive search methodologies of Bayesian inference

The analysis of X-ray photoelectron spectra often faces challenges due to the lack of standardization in modeling approaches, background subtraction methods, and computational algorithms within the field of computer science. The interpretation of XPS data significantly relies on the unique expertise and judgment of individual researchers. Therefore, the objective of this study is to highlight the difficulties associated with analytical methods that depend heavily on the discretion of individual scientists, to elucidate the prevailing models and background subtraction techniques, and to suggest improvements to these methodologies. This endeavor aims to enhance the reliability and reproducibility of XPS analysis, thereby contributing to the advancement of research in this area. By utilizing the information criterion as part of a thorough search methodology in Bayesian inference, we show that our sophisticated analytical techniques significantly outperform others in the analysis of actual X-ray photoelectron spectroscopy (XPS) spectra. This improvement is evidenced through enhanced accuracy and reliability in spectral interpretation, underscoring the efficacy of our methods in practical applications of XPS.

Transformation of the diamond surface with a thin iron coating during annealing and transport properties of the formed conductive layer

In our study, we annealed polycrystalline diamond films with nanometer-thick iron coatings. Based on analysis of X-ray photoelectron spectroscopy data the presence of two catalytic processes was suggested. One is the continuous absorption of sp3 carbon by iron nanoparticles with subsequent extrusion of the sp2 phase from the formed iron carbide, which leads to the creation of deep tracks into the diamond bulk that are filled with graphite stacks. The other process involves a thin layer of iron carbide on the surface and results in the creation of sp2 layers, which are made up of fused graphene-like patches and are oriented mainly along the surface of the diamond film. For the sample annealed at 800 °C for 1 h, the sp2 layers formed exhibit semi-metallic conductivity with quantum corrections caused by disorders. At the same time, no evidence of iron contribution in conductivity of the annealed Fe-coated film was detected, implying that upon transforming the diamond, iron moved quite deep into the bulk. In addition, the formed conductive layer on the diamond surface shows mechanical stability, ensuring the reproducibility of conductivity measurements even after six months of storage in air. The study has revealed the potential for targeted metal-assisted formation of sp2 carbon-based conducting pathways on diamond surfaces for electronic devices.

Surface science insight note: Imaging X‐ray photoelectron spectroscopy

Quantification of X‐ray photoelectron spectroscopy (XPS) data is often limited by the heterogeneous nature of the material surface. However, it is often the case that heterogeneous material contains areas within the analyzed area that are effectively homogeneous. In this Insight note, concepts, and methods used to analyze both XPS data are presented to extract both spatial and spectral information from heterogeneous surfaces. These concepts and methods are applied to a specific material surface that contains three chemical compounds separated spatially. The analysis entails converting XPS image data to spectral data and is designed to highlight the potential of XPS imaging in revealing compositional information correlation with spatial information. Properties of algorithms used to evaluate XPS images and spectra are described to outline their application to image data. A case study of an imaging XPS data set is presented that demonstrates how poor signal‐to‐noise images, where the signal is recorded for 4 s per image, are still open to analysis yielding useful information. Ultimately, the methods presented here will aid in interpreting complex XPS data obtained from spatially complex materials often obtained during extensive cycling, such as conventional or electrocatalysts.