Charged Ions Research Articles

One-dimensional multi-fluid model of the plasma wall transition

A one-dimensional multi-fluid model of the plasma wall transition is presented. The plasma is composed of singly charged positive ions, electrons and negative ions. Positive ions are assumed to obey the continuity, momentum transfer and energy transport equation, while the electrons and negative ions are treated by the continuity and momentum transfer equation. For the positive ions the closure is done by assuming that heat flux in the plasma is zero, while both negative species are treated as isothermal, with the pressure gradient term being proportional to the density gradient. The potential drop in the pre-sheath can be determined either by the electrons or the negative ions – depending on their densities in the unperturbed plasma. It is shown how the boundary density of both particle species can be in some cases determined very precisely.

A multi-reflection time-of-flight setup for the study of atomic clusters produced by magnetron sputtering

The Greifswald multi-reflection time-of-flight setup has been extended with a magnetron sputtering gas aggregation source for the production of atomic cluster ions with sizes ranging from a single to thousands of atoms. This source, combined with a newly added quadrupole mass filter and a linear Paul trap, opens up the possibility of many new atomic-cluster studies not feasible with the setup before. The new components and their interfacing with the previous setup are described, and benchmarking as well as the first experimental results are presented. The capability of the system to handle singly charged ions with masses of several ten thousand atomic mass units is demonstrated.

Refinement of X-ray and electron diffraction crystal structures using analytical Fourier transforms of Slater-type atomic wavefunctions in Olex2.

An implementation of Slater-type spherical scattering factors for X-ray and electron diffraction for elements in the range Z = 1-103 is presented within the software Olex2. Both high- and low-angle Fourier behaviour of atomic electron density and electrostatic potential can thus be addressed, in contrast to the limited flexibility of the four Gaussian plus constant descriptions which are currently the most widely used method for calculating atomic scattering factors during refinement. The implementation presented here accommodates the increasing complexity of the electronic structure of heavier elements by using complete atomic wavefunctions without any interpolation between precalculated tables or intermediate fitting functions. Atomic wavefunctions for singly charged ions are implemented and made accessible, and these show drastic changes in electron diffraction scattering factors compared with the neutral atom. A comparison between the two different spherical models of neutral atoms is presented as an example for four different kinds of X-ray and two electron diffraction structures, and comparisons of refinement results using the existing diffraction data are discussed. A systematic but slight improvement in R values and residual densities can be observed when using the new scattering factors, and this is discussed relative to effects on the atomic displacement parameters and atomic positions, which are prominent near the heavier elements in a structure.

The Future of 2D Materials Production: Graphene and Borophene on larger scale

The production of graphene and borophene, two distinct materials with remarkable properties, is investigated through the manipulation of charged ions in a plasma environment. Plasma, characterized by ionized atoms or molecules, offers a unique setting where diverse chemical reactions can take place. This research focuses on utilizing this environment to create longer-chain graphene and carbon nanotubes by manipulating charged carbon ions. When positively and negatively charged carbon ions coexist within the plasma, they have the potential to interact and form bonds. This interaction results in the growth of extended carbon structures, particularly graphene. By carefully controlling plasma conditions such as temperature, pressure, and composition, scientists can guide the formation of longer-chain graphene and carbon nanotubes from these charged carbon ions. Similarly, the production of borophene, a material composed of boron atoms, also takes place in a plasma state. By introducing positively and negatively charged boron ions into the plasma, these ions interact and potentially form bonds, leading to the growth of extended borophene structures. This innovative approach unlocks the potential for tailored materials with enhanced property.

Cellulose based adsorbent for cationic methylene blue dye removal

New chemically amended (sodium periodate cellulose nanoparticle (NaIO4-CNP) adsorbent material was synthesized from dried fibers of cotton. The synthesized NaIO4-CNP adsorbent material was characterized for functional groups, crystallite size, surface morphology, morphological structure, and particle size) by using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and Brunauer Emmett Teller (BET), instruments, respectively. Then it was investigated to eliminate methylene blue (MB) dye from textile secondary runoff wastewater (SERWW). The physicochemical properties of textile SERWW including organic matter (OM) and inorganic nutrients on the removal capabilities of MB dye was investigated. The adsorption mechanism study was shown that Freundlich isotherm fitted with a maximum removal capability (qmax) of 62.91 mg g−1. The elimination kinetic mechanism fits well to pseudo-second-order and its data recommended the materials (NaIO4-CNP) are effective for wastewater treatment. The MB dye uptake capacities were influenced by the presence of positively charged ions. The NaIO4-CNP adsorbent indicated excellent reproducibility considered as capable adsorption resources to eliminate MB dye from textile SERWW.

Mixed Cluster Ions of Magnesium and C60.

Magnesium clusters exhibit a pronounced nonmetal-to-metal transition, and the neutral dimer is exceptionally weakly bound. In the present study, we formed pristine Mgnz+ (n = 1-100, z = 1-3) clusters and mixed (C60)mMgnz+ clusters (m = 1-7, z = 1, 2) upon electron irradiation of neutral helium nanodroplets doped with magnesium or a combination of C60 and magnesium. The mass spectra obtained for pristine magnesium cluster ions exhibit anomalies, consistent with previous reports in the literature. The anomalies observed for C60Mgn+ strongly suggest that Mg atoms tend to wet the surface of the single fullerene positioning itself above the center of a pentagonal or hexagonal face, while, for (C60)mMgnz+, the preference for Mg to position itself within the dimples formed by fullerene cages becomes apparent. Besides doubly charged cluster ions, with the smallest member Mg22+, we also observed the formation of triply charged ions Mgn3+ with n > 24. The ion efficiency curves of singly and multiply charged ions exhibit pronounced differences compared to singly charged ions at higher electron energies. These findings indicate that sequential Penning ionization is essential in the formation of doubly and triply charged ions inside doped helium nanodroplets.

Testing quantum electrodynamics in extreme fields using helium-like uranium

Quantum electrodynamics (QED), the quantum field theory that describes the interaction between light and matter, is commonly regarded as the best-tested quantum theory in modern physics. However, this claim is mostly based on extremely precise studies performed in the domain of relatively low field strengths and light atoms and ions1–6. In the realm of very strong electromagnetic fields such as in the heaviest highly charged ions (with nuclear charge Z ≫ 1), QED calculations enter a qualitatively different, non-perturbative regime. Yet, the corresponding experimental studies are very challenging, and theoretical predictions are only partially tested. Here we present an experiment sensitive to higher-order QED effects and electron–electron interactions in the high-Z regime. This is achieved by using a multi-reference method based on Doppler-tuned X-ray emission from stored relativistic uranium ions with different charge states. The energy of the 1s1/22p3/2 J = 2 → 1s1/22s1/2 J = 1 intrashell transition in the heaviest two-electron ion (U90+) is obtained with an accuracy of 37 ppm. Furthermore, a comparison of uranium ions with different numbers of bound electrons enables us to disentangle and to test separately the one-electron higher-order QED effects and the bound electron–electron interaction terms without the uncertainty related to the nuclear radius. Moreover, our experimental result can discriminate between several state-of-the-art theoretical approaches and provides an important benchmark for calculations in the strong-field domain.

A very low energy ion beam extraction system design of the GTS ECR ion source at GANIL

The GTS ion source, operated at 14.5GHz, provides multiply charged heavy ion beams for the ARIBE facility at GANIL. The facility variety is limited by the efficiency of the extraction especially in the few keV/q domain. In order to improve the ion source, the extraction system was upgraded numerically using IBSimu. The shape of the plasma and the puller electrodes was changed. It causes the increase of the electric field near the plasma meniscus and allows the use of lower extraction voltages at constant total ion beam current. The required beam parameters were taken from the experimental data. The opportunity of effective low energy beam formation (at a few keV/q or several hundreds eV/q beam energy) was studied. The high current and low energy ion beam production will provide new possibilities for ARIBE facility users.

A critical review and meta-analysis of xenon-on-carbon sputter yield data

A systematic review and meta-analysis of sputter yield data for xenon ions normally incident on graphite at energies below 2000 eV was undertaken to identify systematic errors, determine the best model parameter values to represent yield as a function of energy, quantify uncertainty, and determine if the data support differences in yields for different types of graphite. A critical examination of the 11 published data sets for high density graphite, pyrolytic graphite, and amorphous carbon showed that, in general, they were carefully controlled to minimize errors. The most significant quantifiable systematic errors were those caused by the neglect of doubly charged ions, chemical erosion, and the impact of secondary electron emission on ion flux measurements. The effects of gas uptake and outgassing on mass loss measurements and unrepresentative surface textures may have biased other experiments, but these effects could not be quantified. The semi-empirical Eckstein model for yield as a function of energy was fit to data for the three graphite types using a hierarchical Bayesian statistical model, producing recommended fit parameters and probability distributions representing uncertainty in yields. The results showed that differences in yield for high density graphite and pyrolytic graphite were not statistically significant. Apparent differences in yield for amorphous carbon disappeared when the single data set available for energies below 150 eV was corrected for reasonable values of double ion content. Recommended procedures to avoid systematic errors and additional experiments and modeling to fill in gaps in our understanding are included.

Effect of surface orientation on blistering of copper under high fluence keV hydrogen ion irradiation

Copper and hydrogen are among the most common elements that are widely used in industrial and fundamental research applications. Copper surfaces are often exposed to hydrogen in the form of charged ions. The hydrogen ions can accelerate towards the surface, resulting in an accumulation of hydrogen below the surface. Harmless in low concentrations, prolonged hydrogen exposure can lead to dramatic changes on copper surfaces. This effect is visible to the naked eye in the form of blisters densely covering the exposed surface. Blisters are structural modifications that can affect the physical properties of the surface including, for example, vacuum dielectric strength.Using scanning electron microscopy we found that the blistering of the irradiated polycrystalline copper surface does not grow uniformly with ion fluence. Initially, only some grains exhibit blisters, while others remain intact. Our experiments indicate that grains with the {100} orientation are the most prone to blistering, while the grains oriented in the {110} are the most resistant to it. Moreover, we noticed that blisters assume different shapes correlating with specific grain orientation.Good agreement of experiments with the atomistic simulations explains the difference in the shapes of the blisters by specific behavior of dislocations within the FCC crystal structure. Moreover, our simulations reveal the correlation of the delay in blister formation on surfaces with certain orientations compared to the others with the dependence of the hydrogen penetration depth and the depth and amount of vacancies in copper on the orientation of the irradiated surface.

Modified Wood Fibers Spontaneously Harvest Electricity from Moisture.

With the rapid development of modern society, our demand for energy is increasing. And the extensive use of fossil energy has triggered a series of problems such as an energy crisis and environmental pollution. A moisture-enabled electric generator (MEG) is a new type of energy conversion method, which can directly convert the ubiquitous moisture in the air into electrical energy equipment. It has attracted great interest for its renewable and environmentally friendly qualities. At present, most MEGs still have low power density, strong dependence on high humidity, and high cost. Herein, we report the development of a high-efficiency MEG based on a lignocellulosic fiber frame with high-power-density, all-weather, and low-cost characteristics using a simple strategy that optimizes the charge transport channel and ion concentration difference. The MEG devices we manufactured can generate the open-circuit voltage of 0.73 V and the short-circuit current of 360 μA, and the voltage can still reach 0.6 V at less than 30% humidity. It is possible to drive commercial electronic devices such as light-emitting diodes, electronic displays, and electronic calculators by simply connecting several electric generators in series. Biomass-based moisture-enabled electric generation has a low cost, is easy to integrate on a large scale, and is green and pollution-free, providing clean energy for low-humidity or high-electricity-cost areas.

Atomistic modeling of electromechanical properties of piezoelectric zinc oxide nanowires

Currently, numerous articles are devoted to examining the influence of geometry and charge distribution on the mechanical properties and structural stability of piezoelectric nanowires (NWs). The varied modeling techniques adopted in earlier molecular dynamics (MD) works dictated the outcome of the different efforts. In this article, comprehensive MD studies are conducted to determine the influence of varied interatomic potentials (partially charged rigid ion model, [PCRIM] ReaxFF, charged optimized many-body [COMB], and Buckingham), geometrical parameters (cross-section geometry, wire diameter, and length), and charge distribution (uniform full charges versus partially charged surface atoms) on the resulting mechanical properties and structural stability of zinc oxide (ZnO) NWs. Our optimized parameters for the Buckingham interatomic potential are in good agreement with the existing experimental results. Furthermore, we found that the incorrect selection of interatomic potentials could lead to excessive overestimate (61%) of the elastic modulus of the NW. While NW length was found to dictate the strain distribution along the wire, impacting its predicted properties, the cross-section shape did not play a major role. Assigning uniform charges for both the core and surface atoms of ZnO NWs leads to a drastic decrease in fracture properties.

Spectral composition of secondary electrons based on the Kiefer-Straaten ion track structure model.

The major part of energy deposition of ionizing radiation is caused by secondary electrons, independent of the primary radiation type. However, their spatial concentration and their spectral properties strongly depend on the primary radiation type and finally determine the pattern of molecular damage e.g. to biological targets as the DNA, and thus the final effect of the radiation exposure. To describe the physical and to predict the biological consequences of charged ion irradiation, amorphous track structure approaches have proven to be pragmatic and helpful. There, the local dose deposition in the ion track is equated by considering the emission and slowing down of the secondary electrons from the primary particle track. In the present work we exploit the model of Kiefer and Straaten and derive the spectral composition of secondary electrons as function of the distance to the track center. The spectral composition indicates differences to spectra of low linear energy transfer (LET) photon radiation, which we confirm by a comparison with Monte Carlo studies. We demonstrate that the amorphous track structure approach provides a simple tool for evaluating the spectral electron properties within the track structure. Predictions of the LET of electrons across the track structure as well as the electronic dose build-up effect are derived. Implications for biological effects and corresponding predicting models based on amorphous track structure are discussed.

Precision measurement of M1 optical clock transition in Ni12+

Highly charged ions (HCIs) have drawn significant interest in quantum metrology and in the search for new physics. Among these, Ni12+ is considered as one of the most promising candidates for the next generation of HCI optical clocks, due to its two E1-forbidden transitions M1 and E2, which occur in the visible spectral range. In this work, we used the Shanghai-Wuhan electron beam ion trap to perform a high-precision measurement of the M1 transition wavelength. Our approach involved an improved calibration scheme for the spectra, utilizing auxiliary Ar+ lines for calibration and correction. Our final measured result of the M1 transition wavelength demonstrates a fivefold improvement in accuracy compared to our previous findings, reaching the subpicometer level accuracy. In combination with our rigorous atomic-structure calculations to capture the electron correlations and relativistic effects, the quantum electrodynamic corrections were extracted. Published by the American Physical Society 2024

Selective Zn/Na Ions Insertion into FePO4 Positive Electrode Tuned by Counter Anions in Aqueous Zn‐Based Rechargeable Batteries

AbstractToward the construction of rechargeable batteries utilizing Zn metal has a high theoretical capacity, one of the solutions is to combine with the insertion/deinsertion of Na ions into/from hosts, but in the presence of two coexisting metal cations in dual‐salt electrolytes, it has been often left to spontaneity to determine which cations the host materials react with preferentially. The hybrid aqueous electrolytes containing 1 m Zn‐salt and 6 m Na‐salt were used, and the counter anions were TFSA− and Cl−, respectively. In the TFSA‐based electrolyte, the ligands for Zn ions and Na ions are water molecules to form positively‐charged hydrated cations. In contrast, for the Cl‐based electrolyte, Zn ions undergo partially solvation of Cl− to be stabilized as [ZnCl4(H2O)2]2− with negative charges while Na ions are predominantly hydrated. The galvanostatic discharge/charge tests, AC impedance measurements, and field‐emission electron probe micro analyzer revealed that in the Zn(TFSA)2/NaTFSA system, where both the cations are positively charged, Zn ions with higher charge density were inserted into the FePO4. On the other hand, in the ZnCl2/NaCl system, the FePO4 accommodated Na ions positively charged in the electrolyte solution rather than negatively charged Zn ions.

Commentary on the role of polyoxometalates in nature cybernetic loop

AbstractThe interplay between extraterrestrial, atmospheric, aqueous, interfacial, and hydrothermal processes is crucial for Earth's prebiotic chemistry. Volcanic terrains contain polyoxometalates (POMs). Some polyoxocuprates were identified as building blocks of fumarole minerals produced from high‐temperature gases. The existence of polyoxovanadate anions in acidified reducing volcanic aquifers cannot be excluded. At present, it can only be speculated whether life arose around natural POM deposits and/or around their aqueous phase chemistry through acid‐base and/or redox reactions. This Commentary spans different fields of sciences in nature cybernetic loop to provide impetus to explore gas‐phase chemical reactions of multiply charged POM ions, catalysis by POM‐containing mineral phases, the behavior of POMs under plasma‐initiated ultraviolet photolysis, interactions of POMs with microorganisms, bioorthogonal chemistry of POMs, and engineering POM‐based bionic functions inspired by living organisms.

Multiresponsive Core-Shell Microgels Functionalized by Nitrilotriacetic Acid.

Stimuli-responsive microgels with ionizable functional groups offer versatile applications, e.g., by the uptake of oppositely charged metal ions or guest molecules such as drugs, dyes, or proteins. Furthermore, the incorporation of carboxylic groups enhances mucoadhesive properties, crucial for various drug delivery applications. In this work, we successfully synthesized poly{N-vinylcaprolactam-2,2'-[(5-acrylamido-1-carboxypentyl)azanediyl]diacetic acid} [p(VCL/NTAaa)] microgels containing varying amounts of nitrilotriacetic acid (NTA) using precipitation polymerization. We performed fundamental characterization by infrared (IR) spectroscopy and dynamic and electrophoretic light scattering. Despite their potential multiresponsiveness, prior studies on NTA-functionalized microgels lack in-depth analysis of their stimuli-responsive behavior. This work addresses this gap by assessing the microgel responsiveness to temperature, ionic strength, and pH. Morphological investigations were performed via NMR relaxometry, nanoscale imaging (AFM and SEM), and reaction calorimetry. Finally, we explored the potential application of the microgels by conducting cytocompatibility experiments and demonstrating the immobilization of the model protein cytochromec in the microgels.

Attraction between Like Charged Ions in Ionic Liquids: Unveiling the Enigma of Tetracyanoborate Anions.

Intermolecular interactions in ionic liquids are mainly governed by Coulombic forces. Attraction between cations has been previously observed and was attributed to dispersion interactions between nonpolar moieties, hydrogen bonding, or π stacking. In this study, we present the intriguing behavior of tetracyanoborate anions in ionic liquids that, unlike their dicyanamide and tricyanomethanide counterparts, form dimers in both solid and liquid phases. A joint simulation and experimental study uncovers the origin of such anion-anion attraction: stabilization by induction and dispersion forces between several cyano groups, which is strong enough to overcome electrostatic repulsion. These findings open up new opportunities in the rational design of ionic liquids, where interactions between ions of the same charge can be controlled and fine-tuned by the presence of cyano groups.

EVOLUCIÓN TECNOLÓGICA DE LOS ELECTROLIZADORES PARA LA PRODUCCIÓN DE HIDRÓGENO

Electrolysis is a chemical process that uses electric current to carry out chemical reactions. It was first discovered by the British scientist Michael Faraday in 1833, who conducted a series of experiments in which he passed an electric current through solutions of salts in water. He found that positively charged ions, known as cations, moved towards the negative electrode (anode), while negatively charged ions, known as anions, moved towards the positive electrode (cathode). Faraday also showed that the amount of substance deposited on the electrodes during electrolysis is proportional to the intensity of the electric current and the time of application.

Uniformity optimization of ion beam sputtering coating equipment based on strong current ion source

The widespread application of ion beam sputtering coating, especially in optical devices, requires the improvement of beam current intensity and uniformity of large-area uniform coatings. The advent of high current Penning sources offers a potential solution. This study introduces an automated optimization simulation method based on a three-electrode extraction system to investigate its influence on ion beam quality and uniformity. Focusing on high current intensity and uniformity, our simulation explores the effects of plasma electrode, inhibition electrode, and extraction electrode angles and distances on ion beam performance. Evaluation metrics include average beam intensity density, average energy of a single particle, and reciprocal variance of each macro particle position, which are achieved through normalization functions, allowing comprehensive comparison of simulation results. To assess coating efficiency, we estimate sputtering yield and depth. The study identifies patterns among electrodes and emphasizes the influence of different ion ratios on beam extraction. The results indicate that optimizing the angle of the plasma electrode and the distance of the suppressed electrode yields a highly uniform ion beam for low charge ions. However, for highly charged ions, similar optimization will reduce the current strength, so compensation needs to be achieved through electrode shape optimization. This research provides a model for systematically optimizing the three-electrode extraction system, guiding researchers in achieving optimal solutions based on ion source characteristics and application requirements. Additionally, we introduce a method of estimating the sputtering depth of mixed ion beams. This study provides valuable insights for advancing ion beam sputtering coating technology and reference for making the decision on design and application of ion source.