Low-charge Ions Research Articles

B/P/N/O co-doped hierarchical porous carbon nanofiber self-standing film with high volumetric and gravimetric capacitance performances for aqueous supercapacitors

It is very challenging for carbon materials to gain high volumetric capacitance (Cv) without sacrificing gravimetric capacitance (Cg) as well as high rate and cycling performances to meet requirements for supercapacitors with limited space. Here, B/P/N/O co-doped hierarchical porous carbon nanofiber self-standing film was fabricated by a facile electrospinning and one-step carbonization/activation method using polyacrylonitrile solution containing boric acid and phosphoric acid. The optimized BPNOCNF-45 has high content (24.65 at.%) of heteroatoms, especially the highest content (12.93 at.%) of active heteroatom species (N-5, N-6, B–C, O–I, P2 and P3), high bulk density (1.19 g cm−3), high meso-/macropore ratio (70%), low charge transfer and ion diffusion resistance. These contribute to its prominent Cv (395 F cm−3 at 1 A g−1) while maintaining high Cg (332 F g−1) and excellent rate performance in KOH electrolyte. By comparison, the assembled symmetric supercapacitor in Na2SO4 electrolyte delivers remarkably higher volumetric/gravimetric energy densities (21.1 Wh L−1 at 523.5 W L−1, 17.7 Wh kg−1 at 439.9 W kg−1) and capacitance retention of 90% after 10000 cycles. Furthermore, the assembled flexible supercapacitor also shows excellent capacitance performances. Such a densely co-doped porous carbon nanofiber film has great potential for applications in compact and miniaturized supercapacitors.

Photoionization of low-charged silicon ions

SynopsisSingle and multiple photoionization of Si1+, Si2+, and Si3+ ions have been investigated near the silicon K-edge using the PIPE setup at beamline P04 of the synchrotron light source PETRA III operated by DESY in Hamburg, Germany. Pronounced resonance structures are observed for all ions which are associated with excitation or ionization of a K-shell electron. The experimental cross sections are compared with results from theoretical calculations.

(Invited) Chloride-Ion Concentration Flow Cells for Efficient Salinitygradient Energy Recovery

Salinity gradient (SG) is a natural and renewable energy source, which naturally exists between river water and seawater and can also be created by engineering processes. Here, a novel chloride-ion (Cl−) concentration flow cell based on two symmetrical electrodes (BiCl3, CoCl2, VCl3 or BiOCl) separately by a cation-exchange membrane (CEM) was used as an efficient method to recover SG energy. Analysis from X-ray diffraction and X-ray photoelectron spectroscopy indicated that the concentration flow cell with metal chloride electrode (BiCl3, CoCl2 or VCl3) was based on Cl− extraction and insertion, and that of the BiOCl electrode was depended on Cl– intercalation and deintercalation. Besides, the Donna potential across the CEM was also employed for the SG energy harvest. The cell with BiOCl electrodes had the highest power density of 4.36 W m-2 with synthetic river water (1 g L-1 NaCl) and seawater (30 g L-1 NaCl), which was higher than those of most previous technologies for SG energy recovery. The higher power output could be attributed to the faster kinetics of Cl− intercalation/deintercalation on BiOCl electrodes with a layered structure compared to that of Cl- extraction/insertion on metal chloride electrodes. In addition, the results from cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge suggested that low charge transfer and ion diffusion resistances, and the high ion storage capacities of the BiOCl electrode also benefit its the higher power output.

Changes in Ion-Current Composition in the Process of Field Evaporation of Tungsten at High Temperatures

Field evaporation of tungsten at T ~ 2000 K was studied using a sector magnetic mass spectrometer with a field ion source and a field emission microscope. Only low-charge ions W+2 and W+ of all W isotopes were observed in the process of evaporation. The mass distribution of ion currents of isotopes agreed roughly with the standard isotopic ratio for natural tungsten, although certain deviations from it, which were attributed to fluctuations and the erratic nature of evaporation process, were also detected.

Изменение состава ионного тока в процессе полевого испарения вольфрама при высоких температурах

Steady-state field evaporation of tungsten at high temperatures (T ~ 2000 K) has been studied using a magnetic mass spectrometer equipped with the field ion source. Only low-charged ions (W+2 and W+) have been observed in the course of evaporation. The distribution of the ion currents by tungsten isotopes correspondents to standart isotopic ratio for natural tungsten. Some deviations from standart isotopic ratio were observed owing to fluctuations and unstable nature of evaporation process. O.L. Golubev, N.M. Blashenkov

The FUNPET-a New Hybrid Ion Funnel-Ion Carpet Atmospheric Pressure Interface for the Simultaneous Transmission of a Broad Mass Range.

An atmospheric pressure interface transports ions from ambient pressure to the low-pressure environment of a mass spectrometer. A capillary coupled to an ion funnel is widely used. However, conventional ion funnels do little to negate the large amount of energy picked up by high-mass ions from the gas flow through the capillary. There has been little work done on the effects of gas flow on ion transmission, and the previous studies have all been limited to low-mass, low-charge ions. In this work, we account for the effects of gas flow, diffusion, and electric fields (static and oscillating) on ion trajectories and use simulations to design a new hybrid ion funnel-ion carpet (FUNPET) interface that transmits a broad mass range with a single set of instrument conditions. The design incorporates a virtual jet disruptor where pressure buildup and counter flow dissipate the supersonic jet that results from gas flow into the interface. This, and the small exit aperture that can be used with the FUNPET, reduces the gas flow into the next stage of differential pumping. The virtual jet disruptor thermalizes ions with a broad range of masses (1kDa to 1GDa), and once thermalized, they are transmitted into next region of the mass spectrometer with low excess kinetic energy. The FUNPET interface is easy to fabricate from flexible printed circuit board and a support frame made by 3D printing. The performance of the interface was evaluated using charge detection mass spectrometry. Graphical Abstract ᅟ.

Structural Diversity of Nucleosomes Characterized by Native Mass Spectrometry.

Histone tails, which protrude from nucleosome core particles (NCPs), play crucial roles in the regulation of DNA transcription, replication, and repair. In this study, structural diversity of nucleosomes was investigated in detail by analyzing the observed charge states of nucleosomes reconstituted with various lengths of DNA using positive-mode electrospray ionization mass spectrometry (ESI-MS) and molecular dynamics (MD) simulation. Here, we show that canonical NCPs, having 147 bp DNA closely wrapped around a histone octamer, can be classified into three groups by charge state, with the least-charged group being more populated than the highly charged and intermediate groups. Ions with low charge showed small collision cross sections (CCSs), suggesting that the histone tails are generally compact in the gas phase, whereas the minor populations with higher charges appeared to have more loosened structure. Overlapping dinucleosomes, which contain 14 histone proteins closely packed with 250 bp DNA, showed similar characteristics. In contrast, mononucleosomes reconstituted with a histone octamer and longer DNA (≥250 bp), which have DNA regions uninvolved in the core-structure formation, showed only low-charge ions. This was also true for dinucleosomes with free DNA regions. These results suggest that free DNA regions affect the nucleosome structures. To investigate the possible structures of NCP observed in ESI-MS, computational structural calculations in solution and in vacuo were performed. They suggested that conformers with large CCS values have slightly loosened structure with extended tail regions, which might relate to the biological function of histone tails.

Two color laser self focusing and terahertz generation in multi-ion species plasma

An analytical formalism of self focusing of two co-propagating laser beams, fundamental ω1 and close to second harmonic ω2≈2ω1, in a multi-ion species plasma and resonant terahertz radiation generation has been developed. The nonlinearity arises due to ponderomotive force on electrons by both the beams and subsequent ambipolar redistribution of the plasma. The ions of higher charged state are strongly depleted from the axial region due to space charge field effects and electron charge is largely compensated by the ions of lower charge. When the power of the strong beam equals the critical power for its self-guiding, the plasma provides an oscillatory waveguide for the weak beam; the weak beam shrinks and rebounds when its frequency is lower than that of the strong beam, and it swallows and rebounds when the frequency is higher. When both beams are strong the nonlinearities have cumulative effect on both the beams. The cross coupling of the beams gives rise to nonlinear current giving rise to terahertz radiation at ω=ω2−2ω1 frequency. An axial density ripple aids phase matching and gives rise to higher power conversion efficiency. Self focusing leads to enhancement in conversion efficiency.

Isotopic ratio of evaporated ions, critical ionization distances, and ionization regions in the process of the field evaporation of molybdenum at high temperatures

A magnetic mass spectrometer with a field ion source has been used to study the steady-state field evaporation of molybdenum at a temperature of 1000–2000 K. Ions of all seven molybdenum isotopes have been observed in the process of evaporation; only low-charge ions Mo+2 and Mo+ have been detected. The critical ionization distances and ionization regions for single- and double-charge Mo ions have been identified based on the measured ion energies and the experimentally determined intensity of the evaporation field. It has been demonstrated that ions are produced in the process of field evaporation of surface atoms at certain distances from the emitter surface in a very narrow spatial region.

Simple Synthesis and Supercapacitive Performances of NiMoS4 Particles

A simple method was used to prepare amorphous NiMoS4 particles that were subsequently characterized with X-ray diffraction, X-ray fluorescence spectrum, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrum. The supercapacitive properties of NiMoS4 were measured for the first time. It exhibits high capacitance and low charge ion transfer resistance owing to its accessible multiple valences, amorphous structure and high conductivity of sulfides.

Partial and total dielectronic recombination rate coefficients for W55+ to W38+

Dielectronic recombination (DR) is the dominant mode of recombination in magnetically confined fusion plasmas for intermediate to low-charged ions of W. Complete, final-state resolved partial isonuclear W DR rate coefficient data is required for detailed collisional-radiative modelling for such plasmas in preparation for the upcoming fusion experiment ITER. To realise this requirement, we continue The Tungsten Project by presenting our calculations for tungsten ions to . As per our prior calculations for to , we use the collision package autostructure to calculate partial and total DR rate coefficients for all relevant core-excitations in intermediate coupling (IC) and configuration average (CA) using κ-averaged relativistic wavefunctions. Radiative recombination rate coefficients are also calculated for the purpose of evaluating ionisation fractions. Comparison of our DR rate coefficients for with other authors yields agreement to within 7%–19% at peak abundance verifying the reliability of our method. Comparison of partial DR rate coefficients calculated in IC and CA yield differences of a factor at peak abundance temperature, highlighting the importance of relativistic configuration mixing. Large differences are observed between ionisation fractions calculated using our recombination rate coefficient data and that of Pütterich et al (2008 Plasma Phys. Control. Fusion 50 085016). These differences are attributed to deficiencies in the average-atom method used by the former to calculate their data.

Development of a laser ion source for production of high-intensity heavy-ion beams

A laser ion source has been developed as a high-intensity source for the ion implanter and the single pulsed beam of the azimuthally varying field cyclotron at TIARA. Highly charged beams of C5+ and C6+ ions and low-charged beams of heavy ions such as C, Al, Ti, Cu, Au, and Pt are required for the single-pulse acceleration in the cyclotron and for the ion implanter, respectively. In the vacuum chamber of the ion source, a target holder on a three-dimensional linear-motion stage provides a fresh surface for each laser shot. A large-sized target with a maximum size of 300mm×135mm is mounted on the holder for long-term operation. The ion current (ion charge flux) in the laser-produced plasma is measured by a Faraday cup and time-of-flight spectra of each charge state are measured using a 90° cylindrical electrostatic analyzer just behind the Faraday cup. Carbon-plasma-generation experiments indicate that the source produces intense high- and low-charged pulsed ion beams. At a laser energy of 483mJ (2.3×1013W/cm2), average C6+ current of 13mA and average C5+ current of 23mA were obtained over the required time duration for single-pulse acceleration in the cyclotron (49ns for C6+ and 80ns for C5+). Furthermore, at 45mJ (2.1×1012W/cm2), an average C2+ current of 1.6mA over 0.88μs is obtained.

Effect of tapered magnetic field on expanding laser-produced plasma for heavy-ion inertial fusion

AbstractA laser ion source (LIS) is a promising candidate as an ion source for heavy-ion inertial fusion (HIF), where a pulsed ultra-intense and low-charged heavy ion beam is required. It is a key development for a LIS to transport laser-produced plasma with a magnetic field to achieve a high-current beam. The effect of a tapered magnetic field on laser-produced plasma is demonstrated by comparing the results with a straight solenoid magnet. The magnetic field of interest is a wider aperture on a target side and narrower aperture on an extraction side. Based on the experimentally obtained results, the performance of a scaled LIS for HIF was estimated.

NiCoO2 flowers grown on the aligned-flakes coated Ni foam for application in hybrid energy storage

Abstract Many NiCoO2 flowers with an average diameter of about 4 μm were grown on the NiCoO2 flakes coated Ni foam (denoted as NiCoO2/Ni foam) through a simple hydrothermal method and confirmed by scanning and transmission electron microscopies, X-ray diffraction and X-ray photoelectron spectrum measurements. The NiCoO2/Ni foam with high specific area and porosity was directly used as the working electrode without any binders. The measured specific capacitance of NiCoO2 grown on Ni foam is 756 F/g at 0.75 A/g using a three-electrode setup in 1 M KOH. Considering the high capacity of NiCoO2 and the good stability of rGO, the NiCoO2/Ni foam//rGO hybrid supercapacitor combining NiCoO2/Ni foam and rGO shows very good properties, such as high specific capacitance (82 F/g at 2 A/g based on the total mass of active materials), high energy density (25.7 Wh/kg at 1500 W/kg based on the total mass of active materials), good stability (about 90% capacitance retention after 2000-cycle at 100 mV/s), and low charge ion transfer resistance.

Bipolar corona assisted jet flow for fluidic application

In this paper, we present a study on a jet flow, assisted by low net charge ion wind from bipolar corona discharge setup. The ion wind is simultaneously generated from both positive and negative electrodes placed in parallel, adding momentum to the bulk flow directed alongside the electrodes and focused in the middle of interelectrode space. The electrodes are connected to a single battery-operated power source in a symmetrical arrangement, where the electrode creating charged ions of one polarity also serves as the reference electrode to establish the electric field required for ion creation by the opposite electrode, and vice versa. Multiphysics numerical simulation is carried out with programmable open source OpenFOAM, where the measured current-voltage is applied as a boundary condition to simulate the electrohydrodynamics flow. The jet flow inside the device is verified by hotwire anemometry using hotwires embedded within the device, with the measured values in good agreement with simulation. The corona discharge helped to focus the jet and increased the flow peak velocity from 1.41m/s to 2.42m/s with only 27.1mW of consumed discharge power. The device is robust, ready-to-use and minimal in cost. In addition, as the oppositely charged corona flows are self-neutralized, the generated air flow remains neutral and therefore does not attach to a particular target, which expands the application range. These are important features, which can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, micro blowers, gas mixing, coupling and analysis with space constraints and/or where neutralized discharge process is required, such as circulatory flow heat transfer or the formation of low charged aerosol for inhalation and charged particle deposition.

Determination of the critical ionization distance and ionization zone during high-temperature field evaporation of molybdenum

Steady-state field evaporation of molybdenum at high emitter temperatures (T ∼ 2000 K) has been studied using a magnetic mass spectrometer equipped with a field ion source. Only low-charge ions (Mo+2 and Mo+) have been observed in the course of evaporation. The measured ion energies and evaporating field strengths (Fev) were used to determine the critical ionization distances (xcr) and ionization zones (Δ) for singly and doubly charged ions. The obtained xcr and Δ values show that the formation of ions takes place at a certain distance from the emitter surface.

Electron-impact ionization of Se2+ and Se3+

Electron-impact ionization cross sections for Se2+ and Se3+ are calculated using a semi-relativistic configuration-average distorted-wave (CADW) method. Good agreement between the CADW calculations and recent experimental measurements are found for the single ionization of Se2+ from threshold to 500 eV and for the double ionization of Se2+ from threshold to 225 eV. Good agreement between the CADW calculations and recent experimental measurements are also found for the single ionization of Se3+ from threshold to 200 eV and for the double ionization of Se3+ near the peak of the cross section at 350 eV. Disagreements at other incident electron energies may be due to the complexity of the ionization pathways for low charged Se atomic ions, the various theoretical approximations, and the difficulty in measuring relatively small double ionization events.

Zr/Sn(IV) Phosphonates as Radiolytically Stable Ion-Exchange Materials

Zirconium and tin phosphonates were synthesized to determine ion-exchange preference and radiolytic stability. The Sn and Zr phosphonate materials were found to have preference for highly charged ions (3+) over lower charged ions (1+, 2+). The materials were exposed to 3.18 × 106 Gray from a Co-60 gamma source and were shown to retain their structure and performance. Ion-exchange of radioactive Am-241 with varying pH was also explored. In this paper, we describe these unusual ion-exchangers that are simple to prepare, reproducible, and do not require phosphate addition.

Zirconium(IV) Phosphonate-Phosphates as Efficient Ion-Exchange Materials.

Layered metal phosphonate-phosphate hybrid materials are known to be ion-exchange materials. Hybrids with zirconium metal centers were synthesized at varying phosphonate-phosphate ratios in order to explore the function and charge preference. The zirconium hybrid materials were found to have a range of applicable uses with preference for highly charged ions (3+) over lower charged ions (1+ and 2+). The addition of a large excess of phosphate altered the selectivity, and these materials were able to remove all ions from solution regardless of charge. In this paper, we describe newly synthesized compounds that are simple to prepare, reproducible, stable, and offer a variety of separation schemes.

Possible observation of the isotope effect during field evaporation

The field evaporation of tungsten at high temperatures (T ~ 2000 K) has been studied using a magnetic mass spectrometer equipped with a field ion source. Only low-charge ions (W+2 and W+) have been observed in the course of evaporation for all tungsten isotopes. For singly charged ions only, the number of ions of the heaviest isotope, 186W+, was about one order of magnitude lower than that corresponding to the standard isotope ratio for natural tungsten. An explanation of this anomalous phenomenon is proposed.