Atomic Spectrometry Research Articles

Influence of radio-frequency magnetron sputtering power on electrical characteristics and positive bias stress stability of indium tin zinc oxide thin-film transistors

Abstract As the pursuit of high-quality display panels intensifies, the importance of high-performance thin-film transistors (TFTs) becomes increasingly prominent. Indium tin zinc oxide (ITZO) TFTs, as one of the promising directions for high-performance metal oxide TFTs, impose high demands on their performance and reliability. In this study, the performance and stability of ITZO TFTs fabricated under different radio-frequency magnetron sputtering power conditions were systematically tested and investigated. After sputtering power optimization, the field effect mobility of ITZO TFTs reaches 29.68 cm²/V·s, with a steep sub-threshold swing of 0.17 V/decade, near-zero threshold voltage, and good stability. Using atomic force microscopy and X-ray photoelectron spectroscopy characterization techniques, the thin films were analyzed to elucidate the relationship between sputtering power variations and oxygen vacancies.

Development of Highly Sensitive Techniques of Atomic and Molecular Spectroscopy and Their Application for Cultural Heritage Studies

Development of Highly Sensitive Techniques of Atomic and Molecular Spectroscopy and Their Application for Cultural Heritage Studies

Electrochemical Deterioration of a Gold Thin Film in Bicarbonate Solution: Correlative Optical, Nano-Mechanical, and Chemical Considerations.

The electrochemical dissolution of metals in liquid electrolytes is of great concern for various electrochemical technologies. However, it is also the focus for boosting metal recovery processes, e.g., from electronic wastes, one of which is the extraction of gold (Au) using eco-friendly electrolytes. To shed more light on the possibility and improvement of such metal leaching, this work presents the investigation of electrochemical deterioration of a Au nanofilm coated on a silicon (Si) support─ubiquitous materials in electronic components─in aqueous potassium bicarbonate (KHCO3) electrolyte, a solution widely used in food products. In addition to the time-dependent in situ Raman spectra revealing the reduced reflectivity of Au associated with its molecular degradation, the significant role of the electric double layer (EDL) at the metal/electrolyte interface is also indicated. Analyzing surface adhesion maps and force-distance spectra acquired using atomic force microscopy and spectroscopy (AFM/AFS), metal degradation is related to nanoscale worm-shaped reconstructed surface features that act as local sites of reduced refractive index. Complemented by the non-negligible fraction of K observed on the treated Au surfaces using scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), an electrochemical framework of metal degradation is proposed, depicting the electric-field-induced transport of K+ and H+ ions toward the Au surface regardless of bias polarity and implying the formation of ternary gold hydrides. The consideration of faradic current in the EDL circuit also suggests the occurrence of ternary gold oxides. Such determination is reinforced by the attributability of the polar and electrostatic characteristics of the worm-like features to residual negatively charged anionic clusters of the hydrides and the oxides. The analysis process and the new understanding of metal degradation provide a potential route for inspecting other metal/solution systems.

Synthesis of ZrO2 and its composite with activated carbon for lead adsorption and antibacterial applications

In this study, zirconium oxide (ZrO2) nanoparticles and their composites with activated carbon (AC) were synthesized and further characterized via several instrumentation techniques in order to study their physical, chemical, and structural properties. The synthesized nanomaterials along with bare AC were utilized as adsorbents to remove Pb (II) ions present in aqueous solutions. Various parameters i.e., adsorbent dose, pH, and concentration of adsorbate were considered to examine the adsorption efficiency of ZrO2, AC, and ZrO2@AC with the help of atomic absorption spectroscopy (AAS). The ZrO2@AC nanocomposite, with a surface area of 120.551 m2/g, offered a maximum absorption capacity of 179.53 mg/g for Pb (II) ions. Moreover, the adsorption isothermic variables were estimated to gain a comprehensive understanding of the adsorption mechanism of Pb (II) ions over ZrO2@AC nanocomposite. Additionally, desorption study of Pb (II) ions is also conducted for reusability of the nanocomposite. For valuable application in actual water environment, the antibacterials activity of both ZrO2 and ZrO2@AC was also examined against different bacteria, e.g., Escherichia coli (E. coli), Salmonella enterica (S. enterica), Staphylococcus aureus (S. aureus), and Streptococcus gordonii (S. gordonii). This study confirms the potential of the ZrO2@AC nanocomposite as a sustainable solution for removal of lead ions and microbes from water.

Functional redundancy in Candida auris cell surface adhesins crucial for cell-cell interaction and aggregation

Candida auris is an emerging nosocomial fungal pathogen associated with life-threatening invasive disease due to its persistent colonization, high level of transmissibility and multi-drug resistance. Aggregative and non-aggregative growth phenotypes for C. auris strains with different biofilm forming abilities, drug susceptibilities and virulence characteristics have been described. Using comprehensive transcriptional analysis we identified key cell surface adhesins that were highly upregulated in the aggregative phenotype during in vitro and in vivo grown biofilms using a mouse model of catheter infection. Phenotypic and functional evaluations of generated null mutants demonstrated crucial roles for the adhesins Als4112 and Scf1 in mediating cell-cell adherence, coaggregation and biofilm formation. While individual mutants were largely non-aggregative, in combination cells were able to co-adhere and aggregate, as directly demonstrated by measuring cell adhesion forces using single-cell atomic force spectroscopy. This co-adherence indicates their role as complementary adhesins, which despite their limited similarity, may function redundantly to promote cell-cell interaction and biofilm formation. Functional diversity of cell wall proteins may be a form of regulation that provides the aggregative phenotype of C. auris with flexibility and rapid adaptation to the environment, potentially impacting persistence and virulence.

Presence of Trace Elements in Edible Insects Commercialized through Online E-Commerce Platform.

This study aimed to evaluate the presence of various elements in edible insect-based food products available for human consumption. Several products were analyzed using atomic spectroscopy, and descriptive statistical analysis was conducted with IBM SPSS Statistics 27. The results revealed the presence of elements such as arsenic, cadmium, copper, magnesium, nickel, silver, lead, tungsten, uranium, mercury, platinum, aluminum, beryllium, bismuth, lithium, antimony, and thallium. Significant differences were found based on product type, insect species, and country of origin. The findings underscore the need to assess each insect species for its potential as a food source, taking into account element bioaccumulation factors. A comprehensive, global approach is essential for ensuring the food safety of edible insects as a sustainable protein source. Further research is needed to address these safety concerns.

Green chitosan extraction from Hermetia illucens breeding waste (prepupal cases): Characterization and bioadsorption activity

Heavy metal contamination has harmful consequences for the ecosystem. They are naturally non-biodegradable, and can cause severe ecotoxicity and numerous pathologies. Several bioadsorbents have been used for metal pollution control, and chitosan is one of the biomaterials that has proven to be an efficient adsorbent. The aim of the present work is to exploit the rearing waste of Hermetia illucens (prepupal cases), commonly known as the Black Soldier Fly (BSF), to produce chitin and its derivative chitosan by microwave-assisted process, and to study the interaction of this biopolymer with zinc and cadmium. All the samples obtained were characterized by several methods, including FTIR, XRD, TGA/DSC, 1H NMR, SEM, and viscosimetric studies. The chitosan obtained has interesting physicochemical properties with an acetylation degree (DA) equal to 2.3 %, Molecular weight (Mv) equal to 155 kDa, and a crystallinity index (ICr) around 51.26 %. Chitosan was also found to have an adsorption capacity of Cd and Zn around 141.05 mg·g−1 and 45 mg·g−1 respectively by absorption atomic spectroscopy (AAS). Results confirm the effectiveness of chitosan derived from BSF, obtained through an eco-friendly method, as a sustainable and efficient bioadsorbent for addressing heavy metal contamination.

Preparation of structural colors from lignin: Improving the homogeneity between different raw materials by solvent precipitation fractionation

Structural color materials prepared by lignin colloidal spheres (LCSs) have attracted great interest due to their biocompatibility, biodegradability, multifunctionality, and ability to weaken incoherent scattering. However, the lignin raw materials originating from different biomass resources have distinct heterogeneity leading to a big difference in the size of resultant LCSs via self-assembly, which is a major challenge for the preparation of stable structural colors. In this work, we employ the solvent precipitation method to fractionate the crude lignin samples obtained from corncob, softwood, hardwood, and bamboo, respectively. After solvent precipitation fractionation, the self-assembly behaviors of different lignin samples become similar. The LCSs prepared by fractionated lignin samples show quite similar sizes (212, 202, 215, and 210 nm) compared with the LCSs prepared by crude lignin samples (341, 83, 128, and 253 nm). The quantitative atomic force microscope force spectroscopy demonstrates the improved homogeneity of LCSs prepared by fractionated lignin samples is attributed to similar long-ranged intermolecular forces in self-assembly. By employing LCSs as building blocks, the lignin-based pigments with stable structural colors are successfully prepared. The presented colors are independent of the biomass resource types, which benefits the product stability and large-scale production of lignin-based structural color materials.

Br I spectral line measurements in the range 6000–12000 cm‒1: Part II

The present study uses a high-resolution Fourier Transform Spectrometer to provide data on the spectral line measurements of atomic bromine (Br I) in the 6000 – 12,000 cm‒1 range in the near-infrared spectral region. Bromine electrodeless discharge lamps (EDL) were prepared and utilized as light sources, while light detectors comprised InGaAs and Si diodes. A total of 302 spectral lines were detected using two different resolutions of 0.008 and 0.009 cm‒1, unveiling 104 lines reported for the first time. All observed lines have been assigned new center of gravity wavenumber values. We also present the unidentified lines and blended lines that appeared in our spectra. This study provides critical insights and data that enhance the understanding of atomic bromine spectroscopy.

Optimizing the Structure of a Pt Metal-Chelating Polymer to Reduce Nonspecific Binding for Mass Cytometry.

Mass cytometry is a bioanalytic tool based on atomic mass spectrometry for detecting biomarker expression on individual cells. Current reagents employ metal-chelating polymers binding isotopes of hard metal ions. Polymers bearing chelators for soft metal ions offer the promise for a large increase in multiplexing capabilities, but examples reported so far often have unacceptably high levels of nonspecific binding (NSB). We recently reported a new class of metal-chelating polymers with dipicolylamine (DPA) chelators that could bind Re and Pt. They also showed significant levels of NSB. Here, to reduce the NSB of the Pt-DPA polymer, we grafted water-soluble oligomers to the distal end of the dipicolylamine pendant group. Methoxy(polyethylene glycol) (DP = 24) was effective as was poly(sulfobetaine methacrylate) (DP = 29). Reacting the Pt-Cl bond of the metalated polymer with glutathione was remarkably effective at suppressing NSB. These results open the door to Pt-isotope-based metal-chelating polymers as new mass tags for mass cytometry.

Entrapment of Amphipathic Drugs in Core-Shell Polymeric Nanoparticles under Batch Conditions─The Role of Control and Solubility Parameters.

The amphipathic bioactive compounds curcumin, resveratrol, and mitomycin C, which have similar solubility parameter component distributions, have been studied for encapsulation under batch conditions into core-shell nanocarriers composed of external hydrophobically functionalized polyelectrolytes and an inner matrix of polyesters or polyester blends: poly(l-lactide), poly(lactide-co-glycolide), and/or poly(ethylene succinate). Our contribution comprises determining the influence of process parameters on the properties and quality of the final products, namely core-shell nanoparticles loaded with appropriate drugs, according to process analysis technologymanagement. The crucial roles of the organic phase dosing rates and process temperatures were carefully investigated. Moreover, a technically feasible method of removing organic solvents from aqueous dispersions─stripping with inert gas─was employed and evaluated via FT-IR studies. The experiments were supported by the calculation and analysis of solubility parameters (δ) and dispersion (δd), polar (δp), and hydrogen bond (δh) components utilizing HSPiP software. The payload locus and sample morphology were studied via atomic force microscopy and X-ray photoelectron spectroscopy analyses with Ar+ sputtering. It was demonstrated that dosing rates of organic phases not exceeding ca. 0.5 mL/min per 1 L of aqueous dispersion of hydrophobically functionalized polyelectrolytes made it possible to obtain core-shell nanoparticles of ca. 100-150 nm with a very narrow polydispersity (PdI < 0.2). The locus of amphipathic payloads in nanocarriers, mostly within the core polymeric structure, was in good agreement with the results of solubility parameter component studies: water-insoluble polyesters with both polar and nonpolar interactions between chains serve as good host materials for amphipathic drugs.

Chip-scale sub-Doppler atomic spectroscopy enabled by a metasurface integrated photonic emitter

We demonstrate chip-scale sub-Doppler spectroscopy in an integrated and fiber-coupled photonic-metasurface device. The device is a stack of three planar components: a photonic mode expanding grating emitter circuit with a monolithically integrated tilt-compensating dielectric metasurface, a microfabricated atomic vapor cell, and a mirror. The metasurface photonic circuit efficiently emits a 130 μm wide (1/e2 diameter) collimated surface-normal beam with only −6.3 dB loss and couples the reflected beam back into the waveguide and connecting fiber, requiring no alignment between the stacked components. We develop a simple model based on light propagation through the photonic device to interpret the atomic spectroscopy signals and explain spectral features covering the full Rb hyperfine state manifold. The demonstration of waveguide-to-waveguide coupling through the vapor cell paves the way for atomic ensembles to be used as components in complex photonic integrated circuits, allowing the unique properties of atomic systems to be available for future highly miniaturized optical devices and systems.

Constraints on the variation of physical constants, equivalence principle violation, and a fifth force from atomic experiments

The aim of this paper is to derive limits on various forms of “new physics” using atomic experimental data. Interactions with dark energy and dark matter fields can lead to space-time variations of fundamental constants, which can be detected through atomic spectroscopy. In this study, we examine the effects of a varying nuclear mass mN and nuclear radius rN on two transition ratios: the comparison of the two-photon transition in atomic hydrogen with the hyperfine transition in Cs133 based clocks, and the ratio of optical clock frequencies in Al+ and Hg+. The sensitivity of these frequency ratios to changes in mN and rN enables us to derive new limits on the variations of the proton mass, quark mass, and the QCD parameter θ. Additionally, we consider the scalar field generated by the Yukawa-type interaction of feebly interacting hypothetical scalar particles with Standard Model particles in the presence of massive bodies such as the Sun and Moon. Using the data from the Al+/Hg+, Yb+/Cs, and Yb+(E2)/Yb+(E3) transition frequency ratios, we place constraints on the interaction of the scalar field with photons, nucleons, and electrons for a range of scalar particle masses. We also investigate limits on the Einstein equivalence principle (EEP) violating term (c00) in the Standard Model extension (SME) Lagrangian and the dependence of fundamental constants on gravity. Published by the American Physical Society 2024

Analyzing the Bioactivity of a Novel Bone Cement: An In Vitro Study.

To analyze the effect of bioactivebone cement (BBC) placed in a phosphate buffer saline solution in comparison to mineral trioxide aggregate (MTA). Ten samples each of BBC (group 1) and MTA (group 2) were prepared and stored in a phosphate buffer saline solution. After three days of storage, white precipitates were formed on the surface of the samples. The solution with precipitates from each sample was analyzed for the presence of calcium and phosphate ions with coupled plasma atomic spectroscopy. BBC showed a significant amount of calcium and phosphate release after a seven-day storage period in phosphate buffer saline solution. Calcium release was significantly higher in group 1 (MTA) (p < 0.001) compared to that in group 2 (BBC), while group 2 (BBC) (p < 0.001) exhibited greater phosphate release compared to group 1 (MTA). BBC (group 2) retains its bioactivity when it comes into contact with a stimulated oral environment (STF). This demonstrates that BBC is bioactive in a simulated oral environment. Moreover, it retainedgood handling properties and could be easily manipulated into a dough form. Clinically, in cases of apical surgery, internal resorption or perforation repair where material placement poses difficulty, BBC will prove to be beneficial.

Dual-frequency optical-microwave atomic clocks based on cesium atoms

133Cs, the only stable cesium (Cs) isotope, is one of the most investigated elements in atomic spectroscopy and was used to realize the atomic clock in 1955. Among all atomic clocks, the cesium atomic clock has a special place, since the current unit of time is based on a microwave transition in the Cs atom. In addition, the long lifetime of the 6P3/2 state and simple preparation technique of Cs vapor cells have great relevance to quantum and atom optics experiments, which suggests the use of the 6S−6P D2 transition as an optical frequency standard. In this work, using one laser as the local oscillator and Cs atoms as the quantum reference, we realize two atomic clocks at the optical and microwave frequencies. Both clocks can be freely switched or simultaneously output. The optical clock, based on the vapor cell, continuously operated with a frequency stability of 3.9×10−13 at 1 s, decreasing to 2.2×10−13 at 32 s, which was frequency-stabilized by modulation transfer spectroscopy and estimated by an optical comb. Then, applying this stabilized laser to an optically pumped Cs beam atomic clock to reduce the laser frequency noise, we obtained a microwave clock with a frequency stability of 1.8×10−12/τ, reaching 6×10−15 at 105 s. This study demonstrates an attractive feature for the commercialization and deployment of optical and microwave clocks, and will guide the further development of integrated atomic clocks with better stability. Therefore, this study holds significant practical implications for future applications in satellite navigation, communication, and timing.

Development of borazine-assisted-oriented molecularly imprinted electrochemical sensor for the detection of umifenovir in serum and urine by EIS and DPV methods

Herein, borazine (B3N3) assisted-oriented surface imprinted electrochemical sensor was designed for umifenovir (UMI) detection in serum and urine samples. An imprinted electrochemical sensor was developed via photopolymerization whereas butyl methacrylate monomer (BuMA) was selected as the functional monomer for coordinating the template molecules, UMI in the presence of B3N3 as orientating UMI molecules between polymeric phase and the electrode surface. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to verify the electrochemical characterizations of the alterations at each step of the MIP production process. The created sensor was also characterized via contact angle, Fourier transform infrared spectrophotometry attenuated total reflection (FTIR-ATR), atomic force spectroscopy (AFM), and scanning electron microscopy (SEM) measurements. Furthermore, the electronic and molecular alterations on the electrode surface were assessed using quantum chemical calculations. Using differential pulse voltammetry (DPV) and EIS methods in standard solution and biological fluid samples, UMI was determined separately. The dynamic linear range of the designed sensor under optimized experimental conditions was found to be 0.50–7.50 pM and 0.25–5.00 pM for DPV and EIS methods, respectively. The developed sensor exhibited good recognition ability towards UMI molecules in the presence of its analogues as well as other interferents. As a result, the proposed sensors demonstrated excellent selectivity, high sensitivity, repeatability, and reproducibility performance for UMI analysis in commercial serum and urine samples.

Determination of chromium traces by atomic ionization spectroscopy in aqueous standard solutions and in gallium arsenide using the «rod – flame» atomization system

The results of the determination of trace amounts of chromium in aqueous standard solutions of chromium and in high purity gallium arsenide using atomic ionization spectroscopy are presented. Single — and two-step schemes of chromium atom excitation from the ground state 3d54s 7S3 to septet states 3d54p 7P2,3,4, 3d44s4p 7P2,3,4 were studied using a «rod – flame» atomizer. A mechanism of forming atomic-ionization signal for two-step excitation schemes is revealed. The most effective two step excitation schemes for chromium atoms were determined and experimentally studied at different wavelengths λ1 = 425.4 nm, λ2 = 451.4 nm; λ1 = 425.4 nm, λ2 = 426.1 nm. The low limit of chromium detection in aqueous water solutions was 50 pg/ml. The analytical potentiality of the «rod – flame» system for determining traces of chromium in gallium arsenide solutions has been demonstrated. The possibility of determining traces of chromium in gallium arsenide using a flame – rod atomizer at a level of 5 × 10–7 % is demonstrated. Two methods are proposed to increase the selectivity and sensitivity of atomic-ionization determination of chromium: optimization of the temperature program of the flame – rod atomizer and the use of two-stage excitation of chromium atoms. It is shown that the main interfering factor is the background attributed to the matrix ionization. Methods are proposed to reduce or eliminate the matrix impact, which ensure direct determination of elements in samples.

Precision spectroscopy on 9Be overcomes limitations from nuclear structure

Many powerful tests of the standard model of particle physics and searches for new physics with precision atomic spectroscopy are hindered by our lack of knowledge of nuclear properties. Ideally, these properties may be derived from precise measurements of the most sensitive and theoretically best-understood observables, often found in hydrogen-like systems. Although these measurements are abundant for the electric properties of nuclei, they are scarce for the magnetic properties, and precise experimental results are limited to the lightest of nuclei1–4. Here we focus on 9Be, which offers the unique possibility to use comparisons between different charge states available for high-precision spectroscopy in Penning traps to test theoretical calculations typically obscured by nuclear structure. In particular, we perform high-precision spectroscopy of the 1s hyperfine and Zeeman structure in hydrogen-like 9Be3+. We determine the effective Zemach radius with an uncertainty of 500 ppm, and the bare nuclear magnetic moment with an uncertainty of 0.6 parts per billion— uncertainties unmatched beyond hydrogen. Moreover, we compare our measurements with the measurements conducted on the three-electron charge state 9Be+ (ref. 5), which enables testing the calculation of multi-electron diamagnetic shielding effects of the nuclear magnetic moment at the parts per billion level. Furthermore, we test the quantum electrodynamics methods used for the calculation of the hyperfine splitting. Our results serve as a crucial benchmark for transferring high-precision results of nuclear magnetic properties across different electronic configurations.

Preparation and performance of graphene-doped indium tin oxide coatings on titanium bipolar plate surface

To enhance the corrosion resistance of titanium bipolar plates, indium tin oxide (ITO) coatings doped with varying quantities of graphene were fabricated using the sol-gel method. The coatings' surface morphology and microstructure were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The hydrophobicity of the coatings was evaluated using a contact angle goniometer, and their corrosion resistance in a simulated proton exchange membrane fuel cell (PEMFC) corrosion solution (0.5 mol/L H2SO4 + 2 mg/L HF) was measured using an electrochemical workstation. The findings revealed that increasing graphene doping resulted in a more uniform, smooth, and dense coating surface. The ITO coating primarily consisted of In2O3. However, with graphene doping, diffraction peaks of the InOCl phase appeared, indicating changes in the material's composition and structure. Additionally, the valence peaks of the main elements shifted, reflecting alterations in their chemical states. Graphene doping significantly enhanced the coating's hydrophobicity compared to the undoped ITO coating. The water contact angle of the ITO coating with 0.375 g/L graphene increased from 104° to 126°. Furthermore, this graphene-doped coating demonstrated superior corrosion resistance, with a corrosion current density of 0.06 μA/cm2, representing a decrease by three orders of magnitude compared to the titanium substrate. Additionally, it exhibited the largest capacitive arc radius, indicating enhanced charge transfer resistance and better overall electrochemical stability.

Spectroscopic investigation of oxidation in GaSe 2D layered materials

GaSe, a two-dimensional layered metal monochalcogenide, has recently attracted growing interest due to its unique electronic properties and potential technological applications. In this study, we investigate the oxidation mechanisms and properties of GaSe exposed to air for different durations, with the intensive use of Raman spectroscopy, combined with atomic force microscopy (AFM), photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). Raman analysis reveals the oxidation of GaSe, resulting in the formation of a thin layer comprising Ga2Se3, Ga2O3, and amorphous selenium. Utilizing these signatures, oxidation is then tracked. Raman spectroscopy reveals that GaSe layer becomes oxidized almost immediately after exposure to air. However, the oxidation is a self-limiting process, taking roughly 15 min to construct an 8 Å thick layer of Ga₂O₃. XPS analysis shows a good agreement with Raman analysis. The polarized Raman study suggests that the Ga₂Se₃ and Ga₂O₃ layers tend to reach an oriented structural state over time. In ambient conditions, the intensity of all Raman modes and the luminescence decreases, linked to reduction in GaSe thickness. By using various Raman excitation wavelengths, we highlight the depth-dependent oxidation dynamics in this 2D layered GaSe material.