Charged Ions Research Articles

The effect of activated water on the photosynthetic processes of plants

The article is devoted to the research of the effect of nutrient solutions prepared on the basis of activated water: anolyte and catholyte on glucose synthesis during photosynthesis using the example of seedlings of vegetable crops: Japanese cabbage of the Mizuna variety, peas of the vegetable variety “Zima”, cucumber of the variety “Vsyo putyom”. The research was carried out to determine the mechanism of activated water influence on photosynthesis. As a result, the proposed working hypothesis on the effectiveness of the activated water influence on photosynthetic processes was confirmed. It has been shown that glucose synthesis is closely related to the reduction of absorbed CO2 by NADPH+ and ATP during photophosphorylation, and then their direct participation in this synthesis. It has been established that the increased concentration of hydrogen protons formed during the photolysis of activated water is the reason for the effectiveness of glucose synthesis, and, consequently, productivity. It has been shown that positively charged hydrogen ions H+ involved in photophosphorylation, forming NADPH+, which together with H+ is involved in glucose synthesis, during photolysis of water during photosynthesis have a concentration of ions 3.13·105 times higher in anolyte (534.67·10-4 M/l) than in inactive water (170.67·10-9 M/l), which provides, in comparison with the control, an increase in glucose synthesis by 26.7% for Japanese cabbage of the Mizuna variety; by 39.7% for peas of the vegetable variety “Zima” and by 33.3% for cucumber of the variety “Vsyo Putyom”. At the same time, for plants of vegetable peas “Zima”, an increase in the intensity of growth in the anolyte was noted in comparison with the control by 12.5%.

Exploring the potential of MB4 (M = Cr, Mo, and W) MBenes as high-capacity anode materials for Ca-ion batteries: a DFT approach

In a Ca-ion battery, positively charged calcium ions flow through a separator to the cathode. This leaves a negative charge of electrons on the anode. When charging, this flow is reversed.

Acid-modified biomass-based N-doped O-rich hierarchical porous carbon as a high-performance electrode for supercapacitors.

In contemporary society, the conversion and efficient utilization of waste biomass and its derivatives are of great significance. Carbonized wood (CW) is an easily accessible and cost-effective green resource, but it has limitations as an electrode material due to its low specific surface area, limited active sites and poor conductivity. Therefore, it is crucial to improve the performance of biomass-based materials by using activation, heteroatom doping and modification methods to enhance the specific surface area and active sites. In this study, we developed acid-modified urea-doped activated carbonized wood (AUACW) with a three-dimensional (3D) porous structure and porosity, achieving a high specific surface area of 1321.3 m2 g-1. In addition, the degree of graphitization (ID/IG = 1.0) provides good conductivity and a large number of active sites, which are conducive to charge transfer and ion diffusion. The increase of nitrogen and oxygen elements enhances the surface wettability of the material and provides additional pseudocapacitance. The specific capacitance of AUACW reaches 435.84 F g-1 at 0.8 A g-1 with a 93.6% capacitance retention after 10 000 cycles in a 1 M KOH electrolyte. More attractively, a symmetrical supercapacitor (SSC) based on AUACW delivers an energy density of 22.61 W h kg-1 at a power density of 533.26 W kg-1. This work demonstrates the promising potential of utilizing waste biomass to develop green and valuable carbon materials for supercapacitors.

Kinetic energy distributions of atomic ions from disintegration of argon containing nanoclusters in moderately intense nanosecond laser fields: Coulomb explosion or hydrodynamic expansion.

We report kinetic energies (KE) of multiply charged atomic ions (MCAI) from interactions of moderately intense nanosecond lasers at 532 nm with argon containing clusters, including neat and doped clusters with a trace amount of trichlorobenzene. We develop a mathematical method to retrieve speed and thereby kinetic energy information from analyzing the time-of-flight profiles of the MCAI. This method should be generally applicable in detections of energetic charged particles with high velocities, a realm where velocity map imaging is inadequate. From this analysis, we discover that the KE of MCAI from doped clusters demonstrates a quadratic dependence on the charge of the atomic ions, while for neat clusters, the dependence is cubic. This result confirms the nature of the cluster disintegration process to be dominated by Coulomb explosion. This result bears more similarity to reports from extreme vacuum ultraviolet (EUV) fields with similar intensities, than to reports from near infrared (NIR) intense laser fields. However, the charge state distribution from our experiment is the opposite: we observe more higher charge state ions than reported in EUV fields, and our charge state distribution is actually similar to those reported in NIR fields. We also report a significant effect of the external electric field on the charge state distribution of the atomic ions: the presence of an electric field can significantly increase the charge from the atomic ions, as shown by a three-fold reduction in the average kinetic energy per charge. Although molecular dynamics simulations have been implemented for experiments in the EUV and NIR, our results allude to the need of a concerted effort in this regime of moderately intense nanosecond laser fields. The significant decrease in charge state distribution and the significant increase in KE from doped clusters, compared with neat clusters, is a telltale sign that the true interaction time between the laser field and the cluster may be substantially shorter than the duration of the laser, a welcome relief for molecular dynamics simulations.

Influence of ion and hydration atmospheres on RNA structure and dynamics: insights from advanced theoretical and computational methods.

RNA, a highly charged biopolymer composed of negatively charged phosphate groups, defies electrostatic repulsion to adopt well-defined, compact structures. Hence, the presence of positively charged metal ions is crucial not only for RNA's charge neutralization, but they also coherently decorate the ion atmosphere of RNA to stabilize its compact fold. This feature article elucidates various modes of close RNA-ion interactions, with a special emphasis on Mg2+ as an outer-sphere and inner-sphere ion. Through examples, we highlight how inner-sphere chelated Mg2+ stabilizes RNA pseudoknots, while outer-sphere ions can also exert long-range electrostatic interactions, inducing groove narrowing, coaxial helical stacking, and RNA ring formation. In addition to investigating the RNA's ion environment, we note that the RNA's hydration environment is relatively underexplored. Our study delves into its profound interplay with the structural dynamics of RNA, employing state-of-the-art atomistic simulation techniques. Through examples, we illustrate how specific ions and water molecules are associated with RNA functions, leveraging atomistic simulations to identify preferential ion binding and hydration sites. However, understanding their impact(s) on the RNA structure remains challenging due to the involvement of large length and long time scales associated with RNA's dynamic nature. Nevertheless, our contributions and recent advances in coarse-grained simulation techniques offer insights into large-scale structural changes dynamically linked to the RNA ion atmosphere. In this connection, we also review how different cutting-edge computational simulation methods provide a microscopic lens into the influence of ions and hydration on RNA structure and dynamics, elucidating distinct ion atmospheric components and specific hydration layers and their individual and collective impacts.

On-line generated ozone as a reactive cell gas for tandem quadrupole inductively coupled plasma mass spectrometry.

On-line generated ozone was introduced as the cell gas of tandem quadrupole inductively coupled plasma mass spectrometry. Product ions of the ozone reaction showed that the formation of singly charged monoxide ions and dioxide ions was apparently improved for most elements, resulting in maximum improvement of the signal intensity by over 1000 times.

A phthalocyanine-based polycrystalline interlayer simultaneously realizing charge collection and ion defect passivation for perovskite solar cells

Perovskite solar cells are efficient and cost-effective but have issues with ion migration from light irradiation. This study uses OHGaPc as a passivation layer to improve light stability and charge transport, increasing efficiency.

Size limits and fission channels of doubly charged noble gas clusters.

Small, highly charged liquid droplets are unstable with respect to spontaneous charge separation when their size drops below the Rayleigh limit or, in other words, their fissility parameter X exceeds the value 1. The absence of small doubly charged atomic cluster ions in mass spectra below an element-specific appearance size na has sometimes been attributed to the onset of barrierless fission at X = 1. However, more realistic models suggest that na marks the size below which the rate of fission surpasses that of competing dissociative channels, and the Rayleigh limit of doubly charged van der Waals clusters has remained unchartered. Here we explore a novel approach to form small dicationic clusters, namely by Penning ionization of singly charged noble gas (Ng) clusters that are embedded in helium nanodroplets; the dications are then gently extracted from the nanodroplets by low-energy collisions with helium gas. We observe Ngn2+ ions that are about 40% smaller than previously reported for xenon and krypton and about 20% for argon. These findings suggest that fission barriers have been underestimated in previous theoretical work. Furthermore, we measure the size distributions of fragment ions that are produced by collisional excitation of mass-selected dications. At lowest collision gas pressure, dicationic Kr and Xe clusters that are smaller than previously observed are found to evaporate an atom before they undergo highly symmetric fission. The distribution of fragments resulting from fission of small dicationic Ar clusters is bimodal.

Adsorptive removal of heavy metal ions from model aqueous media using titanium metal-organic framework and its polyvinyl chloride functionalized composite

The present study was conducted on Ti-MOF and its PVC functionalized composite with the objective of toxic heavy metal ions removal from aqueous media. For achieving this purpose, the solvothermal method was used to synthesis Ti-MOF which was then functionalized with PVC for composite synthesis. The synthesized adsorbent materials were then analyzed via different techniques that include the FTIR, XRD, SEM and EDX analysis along with TGA and point of zero charge (PZC). Batch experiments were conducted for nickel (Ni) and copper (Cu) metal ions sorption from water, using the synthesized adsorbents, under different experimental conditions like initial metal ions concentration, pH, adsorbent’s dosage, time of contact and temperature. The sorption of heavy metal ions by the adsorbents was increased with increasing the media dosage and concentration. Whereas, increasing the pH of the system, from pH-2 to pH-10, also enhanced the sorption phenomenon, because of the pronounced forces of attraction between the positively charged adsorbate ions and the adsorbent’s negatively charged surface, accompanied by precipitation at a much higher pH. It was observed that the adsorption on the functionalized adsorbent surface was greater than the parent MOF material because of the availability of a greater number of adsorption sites, increasing the adsorption capacity of Ni ions from 6.436 to 29.2 mg/g and that of Cu ions from 21.414 to 41.616 mg/g. In addition, the composite material was found to have greater affinity towards Cu metal ions as compared to Ni metal ions, which is attributed to the smaller size of Cu metal ions as compared to Ni ions. To determine the adsorption mechanism, various adsorption isotherms were examined. The results concluded that the Langmuir adsorption isotherm was the suitable model to explain the adsorption mechanism.Moreover, thermodynamic parameters like Gibbs free energy (, change in enthalpy, along with the change in entropy, were determined. The sorption process was found to be more spontaneous at lower temperatures, with the exothermic nature of adsorption, in the case of Ni metal ions and the endothermic nature in the case of Cu metal ions.Also, the negative value of ΔS in case of Ni ions adsorption accounts for the decreased disorderliness of the system which is also the opposite tothat of Cu ions adsorption onto the surface of Ti-PVC composite.The PVC functionalized Ti-MOF was thus found to be an effective, durable, and environmentally friendly adsorbent, for the sorption of heavy metal ions from wastewater.

K-X rays induced by helium-like C ions in thick target atoms of different metals

The physical process and experimental phenomena of the interaction between highly charged heavy ions and atoms are very complex, particularly in the intermediate energy region, because of the limitation of accelerator and existing theoretical analysis, less systematic researches, incomplete atomic data, and not so high accuracy. The research of celestial element X-ray data is more scarce and the research of X-ray data of celestial elements is even more scarce. Helium-like C ions with 15–55 MeV kinetic energy provided by the HI-13 MV series accelerator of the China Institute of Atomic Energy are used to bombard Fe, Ni, Nb and Mo thick targets. The HpGe detectors are used to measure the K-X ray emission, and the corresponding K-X ray emission cross sections are obtained. Due to the different ionization degrees of the shell layers of various target atoms, the branching intensity ratio of K<sub><i>β</i> </sub>to K<sub><i>α</i></sub> X rays emitted by Helium-like C ions interacting with Fe and Ni target atoms decreases with the increase of the kinetic energy of the incident ions, while the branching intensity ratio of K-X rays emitted by Nb and Mo target atoms does not change significantly. The K-X ray emission cross section of target atom is calculated by using the formula of thick target cross section, and compared with the results of different theoretical models and proton. The results show that with the increase of the kinetic energy of helium-like C ions, the total emission cross section of the K<sub><i>β</i> </sub>and K<sub><i>α</i></sub> X ray emitted from Fe and Ni target atoms are most consistent with the BEA correction model considering multiple ionization, and the total emission cross section of K<sub><i>β</i> </sub>and K<sub><i>α</i></sub> X ray emitted from Nb and Mo target atoms are closest to the theoretical values of PWBA model. When the energy of proton is the same as that of single nucleon C ion, the cross section of K-X ray produced by proton is about three orders of magnitude smaller than that produced by helium-like C ion.

Impact of impedance on electrochromic properties of W-doped V2O5 films

Two series of W-doped V2O5 films, planar films, and inverse opal films, were synthesized. The evolution of their electrochromic properties, including switching time, cycling stability, and color efficiency (CE), were systematically investigated as a function of electrochemical impedance. Both charge transfer resistance (Rct) and ion diffusion ability (KΩ) increase with the W:V atomic ratio in both planar films and inverse opal films series. KΩ plays a decisive role on coloration switching time, for instance, there exists a range of KΩ where switching time vastly decreases with an increase of KΩ and beyond this range, switching time is independent of KΩ and remains constant. The introduction of macroporosity, however, greatly reduces the low critic KΩ. CE is co-affected by both KΩ and Rct. KΩ and Rct collaboratively impact on EC cycling stability: KΩ plays a key role on cycling stability since the best cycling stability corresponds to highest KΩ. Rct plays its role only when it is low enough to reduce the possibility of chemical dissolution of the intermediate product of vanadium-containing ions: the present critical value could be around 76 Ω.

Tetraquinolines; four linked quinoline units or porphyrinoids.

Tetraquinolines (TEQs) have been recently synthesized and proposed to be a new member of the porphyrinoid family with highly distorted, nonplanar, geometries. In this contribution by studying several molecules, closely related to TEQs, we have suggested that the origin of the nonplanarity of TEQs and their counterparts is a combination of steric strain and the propensity of the molecules to avoid antiaromaticity. The tendency of TEQs to coordinate with doubly charged metal ions can be interpreted in terms of their transition from potential antiaromaticity to nonaromaticity. Even metal-coordinated TEQs do not sustain diatropic ring currents. Although full planarization is not possible because of steric strain, doubly oxidized TEQs and their counterparts sustain moderate global diatropic ring currents and partially planarize. The nature of current density in the molecules is studied in the light of Steiner-Fowler selection rules.

AISHa: an ECRIS for nuclear-physics, new clinical protocols and material experiments

The Advanced Ion Source for Hadrontherapy (AISHa) is an ECR ion source operating at 18 GHz, developed with the aim to produce multiply charged ion beams with low ripple, high stability and reproducibility. Due to its unique peculiarity, it is the most suitable choice for medical applications, but also for nuclear-physics and material experiments. Two sources have been realized: the first at INFN-LNS and the second at the Centro Nazionale di Adroterapia Oncologica (CNAO). The first one, fully commissioned at INFN-LNS, will be used as test-bench for development of new beams and several R&D activities are planned within the IONS experiment to increase plasma confinement and to refine techniques of non-invasive plasma diagnostics to correlate plasma and beam parameters. The second one recently produced the first beam and it will allow to increase the CNAO potential in the field of experimental and industrial research, with the long-term goal of introducing new ionic species into clinical practice such as helium, oxygen and later also iron and lithium, useful for bio-spatial research. In this work, the key peculiarities and the experimental results of the two Aisha ion sources will be presented.

Doubly charged dimers and trimers of heavy noble gases.

Many doubly charged heteronuclear dimers are metastable or even thermodynamically stable with respect to charge separation. Homonuclear dicationic dimers, however, are more difficult to form. He22+ was the first noble gas dimer predicted to be metastable and, decades later, observed. Ne22+ is the only other dicationic noble gas dimer that has been detected so far. Here, we present a novel approach to form fragile dicationic species, by post-ionization of singly charged ions that are embedded in helium nanodroplets (HNDs). Bare ions are then extracted by colliding the HNDs with helium gas. We detect homonuclear doubly charged dimers and trimers of krypton and xenon, but not argon. Our multi-reference ab initio calculations confirm the stability of Kr22+, Kr32+, Xe22+, Xe32+, and Ar22+, but put the stability of Ar32+ towards dissociation to Ar+ + Ar2+ into question.

Graphene quantum dots for biosensing and bioimaging.

Graphene Quantum Dots (GQDs) are low dimensional carbon based materials with interesting physical, chemical and biological properties that enable their applications in numerous fields. GQDs possess unique electronic structures that impart special functional attributes such as tunable optical/electrical properties in addition to heteroatom-doping and more importantly a propensity for surface functionalization for applications in biosensing and bioimaging. Herein, we review the recent advancements in the top-down and bottom-up approaches for the synthesis of GQDs. Following this, we present a detailed review of the various surface properties of GQDs and their applications in bioimaging and biosensing. GQDs have been used for fluorescence imaging for visualizing tumours and monitoring the therapeutic responses in addition to magnetic resonance imaging applications. Similarly, the photoluminescence based biosensing applications of GQDs for the detection of hydrogen peroxide, micro RNA, DNA, horse radish peroxidase, heavy metal ions, negatively charged ions, cardiac troponin, etc. are discussed in this review. Finally, we conclude the review with a discussion on future prospects.

Two-body fragmentation of methane induced by extreme ultraviolet and high charge ions

CH<sub>4</sub> is abundant in planetary atmosphere, and the study of CH<sub>4</sub> dissociation dynamics is of great importance and can help to understand the atmospheric evolution process in the universe. At present, the <inline-formula><tex-math id="M6">\begin{document}$ {\text{CH}}_4^{2 + } \to {\text{CH}}_3^ + + {{\text{H}}^ + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M6.png"/></alternatives></inline-formula> channel has been extensively studied, but the explanation of the dissociation mechanism for this channel is controversial. In this work, the double-photoionization experiment of CH<sub>4</sub> by extreme ultraviolet photon (XUV) in an energy range of 25－44 eV and the collision experiment between 1 MeV Ne<sup>8+</sup> and CH<sub>4</sub> are carried out by using the reaction microscope. The three-dimensional (3D) momenta of <inline-formula><tex-math id="M7">\begin{document}$ {\text{CH}}_3^ + $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M7.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M7.png"/></alternatives></inline-formula> and H<sup>+</sup> ions are measured in coincidence, and the corresponding kinetic energy release (KER) is reconstructed, and fragmentation dynamics from the parent ion <inline-formula><tex-math id="M8">\begin{document}$ {\text{CH}}_4^{2 + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M8.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M8.png"/></alternatives></inline-formula> to the <inline-formula><tex-math id="M9">\begin{document}$ {\text{CH}}_3^ + + {{\text{H}}^ + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M9.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M9.png"/></alternatives></inline-formula> ion pair are investigated. In the photoionization experiment, two peaks in the KER spectrum are observed: one is located around 4.75 eV, and the other lies at 6.09 eV. Following the conclusions of previous experiments and the theoretical calculations of Williams et al. (Williams J B, Trevisan C S, Schöffler M S, Jahnke T, Bocharova I, Kim H, Ulrich B, Wallauer R, Sturm F, Rescigno T N, Belkacem A, Dörner R, Weber T, McCurdy C W, Landers A L 2012 <i>J. Phys. B At. Mol. Opt. Phys.</i> <b>45</b> 194003), we discuss the corresponding mechanism of each KER peak. For the 6.09 eV peak, we attribute it to the <inline-formula><tex-math id="M10">\begin{document}$ {\text{CH}}_4^{2 + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M10.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M10.png"/></alternatives></inline-formula> dissociation caused by the Jahn-Teller effect, because this value is consistent with the energy difference in energy between the <inline-formula><tex-math id="M11">\begin{document}$ {\text{CH}}_4^{2 + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M11.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M11.png"/></alternatives></inline-formula> <sup>1</sup>E initial state and the <inline-formula><tex-math id="M12">\begin{document}$ {\text{CH}}_3^ + /{{\text{H}}^ + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M12.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M12.png"/></alternatives></inline-formula> final state involving the Jahn-Teller effect. For the 4.75 eV peak, we believe that it may come from the direct dissociation of <inline-formula><tex-math id="M13">\begin{document}$ {\text{CH}}_4^{2 + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M13.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M13.png"/></alternatives></inline-formula> without contribution from the Jahn-Teller effect. More specifically, Williams et al. presented the potential energy curve for one C-H bond stretching to 8 a.u., while other C—H bonds are fixed at the initial geometry of the CH<sub>4</sub> molecule. In the reflection approximation, we infer that the extra energy is released from the internuclear distance of 8 a.u. to infinity. It is found that the KER is 4.7 eV, which is consistent with the experimental observation, suggesting that the KER peak at 4.75 eV may arise from the direct dissociation of <inline-formula><tex-math id="M14">\begin{document}$ {\text{CH}}_4^{2 + } $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M14.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20231377_M14.png"/></alternatives></inline-formula> without contribution from the Jahn-Teller effect. In addition, in the 1 MeV Ne<sup>8+</sup> ion collision experiment, it is observed that the released energy values corresponding to the three KER peaks are about 4.65, 5.75, and 7.94 eV. By comparing the branching ratio of each peak with the previous experimental result, it is suggested that the velocity effect is not significant in KER spectra.

Two-body fragmentation of methane induced by extreme ultraviolet and high charge ions

CH<sub>4</sub> is abundant in planetary atmospheres, and the study of CH<sub>4</sub> dissociation dynamics is of great importance and can help to understand the atmospheric evolution process in the universe. At present, the CH<sub>4</sub><sup>2+</sup>→ CH<sub>3</sub><sup>+</sup>+H<sup>+</sup> channel has been extensively studied, but the explanation of the dissociation mechanism for this channel is controversial. In this work, the double-photoionization experiment of CH<sub>4</sub> by extreme ultraviolet photon (XUV) in the energy range of 25-44 eV and the collision experiment between 1 MeV Ne<sup>8+</sup> and CH<sub>4</sub> were carried out on the reaction microscope. The 3D momenta of CH<sub>3</sub><sup>+</sup> and H<sup>+</sup> ions were measured in coincidence, the corresponding kinetic energy release (KER) was reconstructed, and fragmentation dynamics from the parent ion CH<sub>4</sub><sup>2+</sup> to the CH<sub>3</sub><sup>+</sup>+H<sup>+</sup> ion pair were investigated. In the photoionization experiment, we observed two peaks in the KER spectrum, one locates around 4.75 eV, and the other one lies at 6.09 eV. Benefiting from the conclusions of previous experiments and the theoretical calculations of Williams [19] et al, we discussed the corresponding mechanism of each KER peak. For the 6.09 eV peak, we attributed it to the CH<sub>4</sub><sup>2+</sup> dissociation mediated by the Jahn-Teller effect, as this value is consistent with the energy difference between the CH<sub>4</sub><sup>2+</sup> <sup>1</sup>E initial state and the CH<sub>3</sub><sup>+</sup> /H+ final state involving the Jahn-Teller effect. For the 4.75 eV peak, we proposed that it may come from the direct dissociation of CH<sub>4</sub><sup>2+</sup> without the Jahn-Teller effect. In more detail, Williams<sup>[19]</sup> et al presented the potential energy curve for one C-H bond stretching to 8 a.u., while other C-H bonds are fixed at the initial geometry of the CH<sub>4</sub> molecule. Based on the reflection approximation, we deduced the additional energy release from the internuclear distance of 8 a.u. to infinity. We found the sum KER is 4.7 eV, this is consistent with the experimental observation and suggests that the KER peak at 4.75 eV may arise from the direct dissociation of CH<sub>4</sub><sup>2+</sup> without the Jahn-Teller effect. In addition, in the 1 MeV Ne<sup>8+</sup> ion collision experiment, we observed three KER peaks with the mean kinetic energy release values of around 4.65, 5.75, and 7.94 eV. By comparing the branching ratio of each peak with the previous experimental results, it is suggested that the velocity effect is not significant in KER spectra.

Metallic Neutral Vapours Diffusion in Electron Cyclotron Resonance Ion Sources: Fluid Dynamics and Particle Tracing Simulations

Resistive oven technique is used to inject vapours of metallic species in electron cyclotron resonance (ECR) plasma traps, where plasma provides step-wise ionization of neutral metals, producing charged ion beams for accelerators. We present a numerical survey of metallic species suitable for oven injection in ECR ion sources, studying neutrals diffusion and deposition under molecular flow regime. These aspects depend on geometry of the evaporation inlet, thermodynamics, and plasma parameters, which strongly impact on ionization and charge-exchange rate, thus on the fraction of reacting neutrals. We considered diffusion of metals with and without plasma. The plasma and its parameters have been modelled considering an established self-consistent particle-in-cell model. Numerical predictions might be relevant to reduce the metal consumption, to increase the overall efficiency, and to improve the plasma ion source performances. As test case, we studied the 134Cs isotope, as one of the alkali metals of interest for the modern nuclear physics.

Study of nuclear excitation by electron capture via the stopping of highly charged ions

<sec>The long-lived isomer is a potential energy-storage material with good energy storage density and storage period. However, releasing the stored energy from such an isomer is challenging. A recognized method is isomer depletion: the isomer is excited to an adjacent short-lived energy level, followed by de-excitation to the ground state, releasing all the stored energy. Six possible mechanisms for isomer depletion have been proposed, i.e. photoabsorption, coulomb excitation, inelastic scattering, nuclear excitation by electron transition, nuclear excitation by electron capture (NEEC), and electronic bridge. Among them, NEEC has attracted significant attention in recent years.</sec><sec>The NEEC occurs when a free electron is captured into an empty atomic orbital, with the nucleus excited simultaneously. To observe the NEEC, one can utilize the stopping process of high-velocity, high-charge-state ions in solid materials. As injected into a stopping material, the ions will be decelerated and capture electrons in the material. In the resonant process of NEEC, the sum of the binding energy and the kinetic energy of the free electron matches the energy required for nuclear excitation. If they do not match, or if the orbitals are already occupied by electrons, the NEEC cannot occur, as indicated by the red arrows in the figure. <inline-formula><tex-math id="M2">\begin{document}$ ^{93{\mathrm{m}}} {\mathrm{Mo}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M2.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M2.png"/></alternatives></inline-formula> is an ideal candidate for NEEC measurements. It is an isomeric state with an excitation energy of 2.4 MeV, a spin-parity of <inline-formula><tex-math id="M3">\begin{document}$21/2 ^+ $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M3.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M3.png"/></alternatives></inline-formula>, and a half-life of 6.85 h. In addition, there is an energy level with a spin-parity of <inline-formula><tex-math id="M4">\begin{document}$17/2 ^+ $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M4.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M4.png"/></alternatives></inline-formula> and half-life of 3.5 ns; its excitation energy is 4.8-keV higher than that of <inline-formula><tex-math id="M5">\begin{document}$ ^{93{\mathrm{m}}} {\mathrm{Mo}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M5.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M5.png"/></alternatives></inline-formula> and primarily de-excites to the <inline-formula><tex-math id="M6">\begin{document}$ 13/2^+ $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M6.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M6.png"/></alternatives></inline-formula> state through a 268-keV gamma ray. This level is referred to as the triggering level in the NEEC process. Once excited to the triggering level, the nucleus decays immediately to the ground state, releasing energy of about 2.4 MeV.</sec><sec>In 2018, Chiara et al. reported the first experimental observation of <inline-formula><tex-math id="M7">\begin{document}$ ^{93{\mathrm{m}}} {\mathrm{Mo}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M7.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M7.png"/></alternatives></inline-formula> isomer depletion with a probability of 1.0(3)%, which was attributed to the NEEC mechanism. However, the following theoretical calculations fail to reproduce such a high probability. In 2022, another experiment was devoted to measuring the depletion of <inline-formula><tex-math id="M8">\begin{document}$ ^{93{\mathrm{m}}} {\mathrm{Mo}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M8.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M8.png"/></alternatives></inline-formula> in the stopping process. The measurements were performed at the Heavy Ion Research Facility in Lanzhou. However, no characteristic 268-keV transition caused by isomer depletion was observed, and it was inferred that the upper limit of the excitation probability was about <inline-formula><tex-math id="M9">\begin{document}$2\times 10^{-5} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M9.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M9.png"/></alternatives></inline-formula>, which is different from the previously reported value of 1%. The beam energy in the Lanzhou experiment is lower than that of the previous data, which can lead to different depletion probabilities. Thus, further experiments are required to clarify this issue.</sec><sec>In this study, two experiments related to NEEC are conducted, the reliability of the experimental results is evaluated from a new perspective of error analysis, and a design scheme is provided for implementing further experiments. According to the proposed experimental setup, the recoil energy is considerably increased and particle-identification devices are added. The detectors for particle identification can cause energy loss, thus the increasing of the recoil energy is also a prerequisite for particle identification. Considering the recoil energy, production cross-section, and the population of high-spin states that can decay to<inline-formula><tex-math id="M10">\begin{document}$ ^{93{\mathrm{m}}} {\mathrm{Mo}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M10.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M10.png"/></alternatives></inline-formula>, we recommend the <inline-formula><tex-math id="M11">\begin{document}$ ^{94}{\mathrm{Zr}}+ ^{4} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M11.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240276_M11.png"/></alternatives></inline-formula>He as the beam-target candidate for future experiments based on the secondary beam line. In addition, a simple design for particle identification is also introduced in this study.</sec>

Dielectronic recombination experiment of Na-like Kr<sup>25+</sup> at heavy ion storage ring CSRe

The experimental study of precision spectroscopy of dielectronic recombination (DR) of highly charged ions is not only important for astronomical plasma and fusion plasma, but also can be used as a new precision spectroscopy to test the strong-field quantum electrodynamic effect, measure isotope shift, and extract the radius of atomic nuclei. An specially designed electron beam energy detuning system for electron-ion recombination precision spectroscopy experiments has been installed on the heavy ion storage ring CSRe in Lanzhou, China, where the electron-ion collision energy in the center-of-mass system can be detuned to 1 keV, and an independently-developed plastic scintillator detector and multiwire proportional chamber detector have been installed downstream of the electron cooler of the CSRe for detecting recombined ions. The multiwire proportional chamber detector has the ability to non-destructively monitor the profile of the ion beam in real-time while acquiring the recombined ion counts, providing guidance for optimizing the ion beam. On this basis, the first test experiment on dielectronic recombination of Kr<sup>25+</sup> ions is carried out at the CSRe, and the dielectronic recombination rate coefficients in a range of 0–70 eV in the frame of center-of-mass are measured. In order to fully understand the experimental results, we calculate the dielectronic recombination rate coefficient of the Kr<sup>25+</sup> ion by using the flexible atomic code (FAC) and make a detailed comparison with the experimental result, showing that they are in good agreement with each other, and only the resonance energy values of the two resonance peaks at 1.695 eV and 2.573 eV are significantly different. In addition, the DR resonance energy values and intensities are obtained by fitting the experimental results in a range of 0–35 eV, and we find that the transition 3s→4l (∆<i>n</i> = 1) contributes significantly to the experimental spectral lines. Furthermore, we compare the plasma rate coefficients derived from the DR rate coefficients with those derived from the AUTOSTRUCTURE and FAC theories, which differ by 20 percent in a temperature range less than 10<sup>6</sup> K. The experimental results show that the DR experimental platform of the CSRe has very good stability and reproducibility, and can provide support for the future DR experiments of highly charged ion, i.e. for testing strong-field quantum electrodynamics effect and measuring the properties of atomic nuclei.