Primary Ion Research Articles

Helium metastable density determination in the COST reference source by absolutely calibrated optical emission spectroscopy

Helium metastable densities in the COST Reference Microplasma Jet are estimated for a variety of He/N2 admixtures and dissipated powers by applying a collisional-radiative model to absolutely calibrated optical emission spectroscopy measurements. This is accomplished by delineating the excitation mechanisms that result in the N2(C–B) and N2+(B–X) emission bands, the latter of which is strongly coupled to the presence of helium metastables. A number of other plasma parameters are established and discussed for each operating condition including the electron energy distribution function, reduced electric field, rate constants, and electron density. With these parameters, the reaction rates for the primary ionization pathways are also calculated, emphasizing the importance of helium metastables for discharge sustainment. Good agreement with the existing literature is found for most plasma parameters and for helium metastable densities, in particular. A clear [N2]−1 relationship between the nitrogen concentration and density of helium metastables is demonstrated, as has been identified in previous studies in analogous atmospheric pressure plasma jets. This validates the efficacy of this optical technique for determining helium metastable densities and establishes it as a viable, and in many cases, more accessible alternative to other means of quantifying helium metastables in low-temperature plasmas.

Development of a Cone Homooxacalix[3]arene-Based Fluorescent Chemosensor for the Selective Detection of Biogenic Ammonium Ions in Protic Solvents.

We report here on the development of a fluorescent cone homooxacalix[3]arene-based receptor with a pyrene unit on the wide rim of the macrocycle (Ox3F) for the selective detection of primary ammonium ions, including those of biological importance. Ox3F was synthesized efficiently via an innovative strategy that enables the regio- and iteroselective wide rim functionalization of the readily available p-tBu-substituted homooxacalix[3]arene precursor. Nuclear magnetic resonance studies and in silico methods highlighted the endo-complexation of primary ammonium ions, including the protonated form of biogenic dopamine, tryptamine, serotonin, mexamine, and 3-iodothyronamine. The binding mode is similar for all guests with the ion deeply inserted into the polyaromatic cavity, enabling the NH3+ head to establish three hydrogen bonds with the ethereal oxygens of the macrocycle. Fluorescence quenching of the pyrene unit was observed following the π-π interaction between the pyrene moiety and the aromatic groups of serotonin, mexamine, and 3-iodothyronamine. No quenching was observed upon complexation of the smaller aromatic neurotransmitter dopamine as well as aliphatic amines and polyamines. This study presents a novel approach for biologically relevant ammonium ion chemosensing with ongoing efforts focused on translating these systems for aqueous environment applications.

Soft ionization mechanisms in flexible µ-tube plasma-elucidation of He-, Ar-, Kr-, and Xe-FµTP.

The soft ionization mechanism of helium-based plasma seems to be understood while it still remains challenging in argon-based plasma, although many studies have used argon plasmas as a soft ionization source with good ionization efficiencies. In this study, helium, argon, krypton, and xenon were fed into the same discharge geometry, a flexible micro-tube plasma (FµTP), to determine the ionization mechanisms. The FµTPs operated with the named noble gases obtained comparable ionization efficiencies by MS measurements. The optical emission results showed that N2+ were the dominant ions within the helium-FµTP and noble gas ions were dominant for the other plasmas. These ions support the development of excitation and eventually stop at the end of the capillary. Therefore, Penning ionization and charge transfer between plasma and ambient air/analytes in the open atmosphere have been proven not to be the primary soft ionization mechanism. Furthermore, it was found that photoionization played a minor role in soft ionization. Using helium as a diagnosis gas in front of the discharge capillary nozzle of the FµTP, where the sample is usually positioned, shows that helium can be ignited by all of these FµTPs. This demonstrates that the excitation of a diagnosis gas as well as the ionization of analytes is independent of the type of the discharge gas. An alternative mechanism that a transient potential created by the ions is responsible for the soft ionization is subsequently proposed.

Tof-SIMS spectra of historical inorganic pigments: Copper-, zinc-, arsenic-, and phosphorus-containing pigments in negative polarity

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is increasingly used to analyze cultural heritage materials because it can simultaneously detect organic and inorganic materials while mapping them on a surface. The precise identification of a pigment in a specific layer of a painting or of remaining color on a statue can inform about the technique used or the time of manufacture as well as expose possible forgeries when anachronistic ingredients are identified. Reference spectra are required to confidently identify a given pigment using ToF-SIMS. This paper focuses on eight pigments containing copper, zinc, arsenic, or phosphate, all manufactured following historical recipes. The negative polarity ToF-SIMS reference spectra using a Bi3+ primary ion species are presented here. Presented together, these spectra and corresponding tables of secondary ions provide a valuable help in differentiating these pigments because copper, zinc, arsenic, or phosphate, combined with oxygen, share many mass interferences.

Cationization agent affects the stability of secondary ions in MeV-SIMS

The work presents studies of the cationization agent effect on the ionization efficiency, and on the stability of secondary molecules, which are desorbed from the surface as a result of bombardment by MeV primary ions. Different organic molecule standards were mixed with various trifluoroacetate (TFA) salts, namely AgTFA, LiTFA, NaTFA and KTFA, with Ag, Li, Na and K being common cationization agents of secondary ions besides hydrogen. Results show modest differences in ionization efficiency, and significant variation of secondary ions’ stability when different cationization agents are attached to the molecule. For all reference samples, lithium provided the most stable secondary ions with almost none detected fragmentations after the desorption, while secondary ions with attached potassium were measured as much less stable, and the ratio between neutrals (fragments) and normal positive ions is estimated to be more than 0.2. However, even potassium – ionized molecules were recognized as more stable than protonated molecules.

Tof-SIMS spectra of historical inorganic pigments: Copper-, zinc-, arsenic-, and phosphorus-containing pigments in positive polarity

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is increasingly used to analyze cultural heritage materials because it can simultaneously detect organic and inorganic materials while mapping them on a surface. The precise identification of a pigment in a specific layer of a painting or of remaining color on a statue can inform about the technique used or the time of manufacture as well as expose possible forgeries when anachronistic ingredients are identified. Reference spectra are required to confidently identify a given pigment using ToF-SIMS. This paper focuses on eight pigments containing copper, zinc, arsenic, or phosphate, all manufactured following historical recipes. The positive polarity ToF-SIMS reference spectra using a Bi3 + primary ion species are presented here. Presented together, these spectra and corresponding tables of secondary ions provide a valuable help in differentiating these pigments, because copper, zinc, arsenic, or phosphate, combined with oxygen, share many mass interferences.

Chemical characteristics, formation mechanisms, and geological evolution processes of high-salinity coal reservoir water in the Binchang area of the southern Ordos Basin, China

The chemical characteristics of coal reservoir water are important for studying the formation and enrichment of biogenic coalbed methane (BCM). Based on geological and sampling test data, this paper studied the geochemical characteristics and formation mechanisms of high-salinity coal reservoir water (CRW) in the Jurassic Yan'an Formation of the Binchang area in the southern Ordos Basin. The results show that the TDS contents of the CRW in the Binchang area are between 7577.38 and 15,138.61 mg/L (av. 13,268.95 mg/L), which is high-salinity brackish water. The ion types of CRW are mainly Na+, Cl− and HCO3−, and the correlations between TDS and Na+ and Cl− are close to 1. The Piper trilinear diagram indicates that the evolution direction of the CRW is deep concentrated brine, and the hydrochemical type is the NaCl type. The 127I concentrations of CRW are between 285 and 484 μg/L, which are much higher than the values of 55.88 μg/L for seawater. The results of 129I dating show that the minimum age of the CRW in the study area is between 6.7 Ma and 39.97 Ma, which is much younger than the actual geological age of the Yan'an Formation. The hydrogen and oxygen isotope results show that the CRW in the study area experiences an apparent oxygen drift, indicating that the coal reservoir of the Yan'an Formation has good sealing and a long retention time for the CRW. The hydrodynamic factors show that the hydrodynamic conditions of the coal reservoir are weak, and the primary ions in the CRW originated from the dissolution of salt rocks. The main ion differentiation indices show that high-salinity coal seam water is mainly formed by evaporation, and the ion exchange between CRW and the surrounding rock and the alternating adsorption of cations in water are very weak. Evaporation and diagenesis lead to an increase in the contents of Na+, Cl− and I+ in coalbed water, which in turn leads to an increase in the total dissolved solids contents of CRW and its evolution toward concentrated brine. The genesis and evolution of the CRW in the study area are affected by the combination of the relationships among the paleoclimate, aquifers and aquifuges, and tectonic evolution processes. The CRW in the study area has experienced five evolution stages, i.e., sedimentary water and diagenetic water, high-salinity infiltration water, primary mixed water, paleoatmospheric precipitation recharge water, and secondary mixed water. The above understanding can provide a basis for studying the formation period and accumulation mechanism of BCM and provide a hydrogeological basis for water resource utilisation and pollution prevention and the control of high-salinity water.

Spatial resolution improvements with finer-pitch GEMs

Gas Electron Multipliers (GEMs) are used in many particle physics experiments, employing their `standard' configuration with amplification holes of 140 μm pitch in a hexagonal pattern. However, the collection of the charge cloud from the primary ionisation electrons from the drift region of the detector into the GEM holes affects the position information from the initial interacting particle. In this paper, the results from studies with a triple-GEM detector with an X-Y-strip readout anode are presented. It is demonstrated that GEMs with a finer hole pitch of here 90 μm improve the detector's spatial resolution. Within these studies, also the impact of the front-end electronics on the spatial resolution was investigated, which is briefly discussed in the paper.

Specificity of Photochemical Energy Conversion in PhotosystemI from the Green Microalga Chlorella ohadii.

Primary excitation energy transfer and charge separation in photosystemI(PSI) from the extremophile desert green alga Chlorella ohadii grown in low light were studied using broadband femtosecond pump-probe spectroscopy in the spectral range from 400 to 850nm and in the time range from 50fs to 500ps. Photochemical reactions were induced by the excitation into the blue and red edges of the chlorophyll Qy absorption band and compared with similar processes in PSI from the cyanobacterium Synechocystissp. PCC6803. When PSI from C.ohadii was excited at 660nm, the processes of energy redistribution in the light-harvesting antenna complex were observed within a time interval of up to 25ps, while formation of the stable radical ion pair P700+A1- was kinetically heterogeneous with characteristic times of 25 and 120ps. When PSI was excited into the red edge of the Qy band at 715nm, primary charge separation reactions occurred within the time range of 7ps in half of the complexes. In the remaining complexes, formation of the radical ion pair P700+A1- was limited by the energy transfer and occurred with a characteristic time of 70ps. Similar photochemical reactions in PSI from Synechocystis6803 were significantly faster: upon excitation at 680nm, formation of the primary radical ion pairs occurred with a time of 3ps in ~30% complexes. Excitation at 720nm resulted in kinetically unresolvable ultrafast primary charge separation in 50% complexes, and subsequent formation of P700+A1- was observed within 25ps. The photodynamics of PSI from C.ohadii was noticeably similar to the excitation energy transfer and charge separation in PSI from the microalga Chlamydomonas reinhardtii; however, the dynamics of energy transfer in C.ohadii PSI also included slower components.

Chain electrospray ionization mass spectrometry for ultra-low volume sample analysis

In this work, chain electrospray ionization (chain-ESI) was developed to efficiently ionize trace samples for mass spectrometry analysis. The primary ion source was found to have the ability to induce secondary electrospray ionization with an extraordinarily low sample consumption rate in the picoliters per minute (pLs/min). This allows low volume sample to generate substantial tandem mass spectrum (MS2) data for metabolite annotations. Notably, chain-ESI can effectively prevent the electro-redox reaction in the process of electrospray, so as to reflect the native state of the analytes. Furthermore, from a single Broussonetia papyrifera (B. papyrifera) trichome and a single A549 cancer cell, 1426 and 617 metabolites were detected respectively. All of those observations demonstrated that chain-ESI offers the advantages of direct, rapid analysis with extreme-low volumes and high coverage, enabling the measurement of bio-information in low volume samples.

A comparative study on the spectral characteristics of nanosecond pulsed discharges in atmospheric He and a He+2.3%H2O mixture

Nanosecond pulsed discharges at atmospheric pressure in a pin-to-pin electrode configuration are well reproducible in time and space, which is beneficial to the fundamentals and applications of low-temperature plasmas. In this experiment, the discharges in helium (He) and He with 2.3% water vapor (H2O) are driven by a series of 10 ns overvoltage pulses (~13 kV). Special attention is paid to the spectral characteristics obtained in the center of discharges by time-resolved optical emission spectroscopy. It is found that in helium, the emission of atomic and molecular helium during the afterglow is more intense than that in the active discharge, while in the He+2.3%H2O mixture, helium emission is only observed during the discharge pulse and the molecular helium emission disappears. In addition, the emissions of OH(A-X) and Hα present similar behavior that increases sharply during the falling edge of the voltage pulse as the electrons cool down rapidly. The gas temperature is set to remain low at 540 K by fitting the OH(A-X) band. A comparative study on the emission of radiative species (He, He2, OH and H) is performed between these two discharge cases to derive their main production mechanisms. In both cases, the dominant primary ion is He+ at the onset of discharges, but their He+ charge transfer processes are quite different. Based on these experimental data and a qualitative discussion on the discharge kinetics, with regard to the present discharge conditions, it is shown that the electron-assisted three-body recombination processes appear to be the significant sources of radiative OH and H species in high-density plasmas.

Study of long term stability of a 50 liters TPC, based on TRIPLE-GEM with optical readout, for the CYGNO experiment

The CYGNO project aims to study rare events, as low-mass (few GeV) Dark Matter (DM) particle or solar neutrino interactions, exploiting the approach of the optical readout of the scintillation light produced in the amplification in a multiple Gas Electron Multiplier (GEM) structure, of the primary ionization originated in large volume Time Projection Chamber (TPCs).The volume is filled with an He:CF4 gas mixture at atmospheric pressure. The 3D topology, and therefore direction of the recoils, is reconstructed thanks to the combined use of high-granularity, high sensitivity sCMOS cameras, for the precise tracking of the projection of the recoils on the GEM plane, and of fast light sensors in order to obtain the coordinate perpendicular to the camera plane.To conclude the R&D phase, the 50 L prototype, called Long Imaging ModulE (LIME), was moved underground at the Laboratori Nazionali del Gran Sasso (LNGS) in order to study the performance of the CYGNO experimental approach in a low background environment and to assess the contributions to the background from different sources, also comparing with Monte Carlo simulations.Stability studies and the effects of environmental condition on the light yield will be discussed, focusing on the effect of humidity on the detector response and stability amount and rate of self-sustaining micro-discharges. This is a crucial step towards the development of a large demonstrator.

Temporal Transcriptomic Profiling Reveals Dynamic Changes in Gene Expression of Giant Freshwater Prawn upon Acute Saline-Alkaline Stresses.

Bicarbonate and sulfate are among two primary ion constituents of saline-alkaline water, with excessive levels potentially causing metabolic disorders in crustaceans, affecting their molting and interrupting development. As an economically important crustacean species, the molecular adaptive mechanism of giant freshwater prawn Macrobrachium rosenbergii in response to the stress of bicarbonate and sulfate remains unexplored. To investigate the mechanism underlying NaHCO3, Na2SO4, and mixed NaHCO3, Na2SO4 stresses, M. rosenbergii larvae were exposed to the above three stress conditions, followed by total RNA extraction and high-throughput sequencing at eight distinct time points (0, 4, 8, 12, 24, 48, 72, and 96h). Subsequent analysis revealed 13, 16, and 13 consistently identified differentially expressed genes (DEGs) across eight time points under three stress conditions. These consistently identified DEGs were significantly involved in the Gene Ontology (GO) terms of chitin-based cuticle development, protein-carbohydrate complex, structural constituent of cuticle, carnitine biosynthetic process, extracellular matrix, and polysaccharide catabolic process, indicating that alkaline stresses might potentially impact the energy metabolism, growth, and molting of M. rosenbergii larvae. Particularly, the transcriptome data revealed that DEGs associated with energy metabolism, immunity, and amino acid metabolism were enriched across multiple time points under three stress conditions. These DEGs are linked to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including glycolysis/glucogenesis, amino sugar and nucleotide sugar metabolism, and lysine degradation. Consistent enrichment findings across the three stress conditions support conclusions above. Together, these insights are instrumental in enhancing our understanding of the molecular mechanisms underlying the alkaline response in M. rosenbergii larvae. Additionally, they offer valuable perspectives on the regulatory mechanisms of freshwater crustaceans amid saline-alkaline water development.

Tuning the Electronic Characteristics of Monolayer MoS2‐Based Transistors by Ion Irradiation: The Role of the Substrate

AbstractThis study explores defect engineering in 2D materials using ion beam irradiation to modify the electrical and optical properties with potential in advancing quantum electronics and photonics. Helium and neon ions ranging from 5 to 7.5 keV are employed to manipulate charge transport in monolayer molybdenum disulfide (MoS2). In situ electrical characterization occurs without vacuum breakage post‐irradiation. Raman and photoluminescence spectroscopy quantify ion irradiation's impact on MoS2. Small doses of helium ion irradiation enhance monolayer MoS2 conductivity in field‐effect transistor geometry by inducing doping and substrate charging. Findings reveal a strong correlation between the electrical properties of MoS2 and the primary ion used, as well as the substrate on which the irradiation occurred. Using hexagonal boron nitride (h‐BN) as a buffer layer between MoS2 flake and SiO2 substrate yields distinct alterations in electrical behavior subsequent to ion irradiation compared to the MoS2 layer directly interfacing with SiO2. Molecular dynamics simulations and density functional theory provide insight into experimental results, emphasizing substrate influence on measured electrical properties post‐ion irradiation.

Signal oscillations in helium scattering by bismuth atoms in the low energy range

Low Energy Ion Scattering (LEIS) analysis of bismuth selenide (Bi2Se3), a strong 3D topological insulator, revealed oscillations of the detected signal in dependence on primary ion beam energy. Bismuth is a part of the group of elements where oscillatory behaviour was already noticed, such as gallium, indium, or lead. Generally, it is ascribed to quasi-resonant charge exchange processes between primary ion and target atom. Moreover, clear differences exist between data for target atoms in elemental form and for atoms in compound form. A study of Bi signal yields in different material forms was performed for primary He+ projectiles within the energy range from 0.50 to 6.00 keV. A foil of pure Bi, Bi2Se3, Bi2O3 and thin Bi films deposited on several substrates (SiO2, CuOx) by Molecular Beam Epitaxy were analysed. The energy shift in the position of oscillations was observed when the oxygen atoms were present at the surface and bonded to Bi atoms. A description of the Bi ion yield variation is provided to facilitate the quantification process in LEIS.

Selective Covalent Basal Plane Modification as a Probe of Hydroxide Ion Conduction Pathways in Magnesium Aluminum Layered Double Hydroxides.

Understanding ionic conduction in layered double hydroxides (LDHs) is a crucial step towards utilizing them as solid, hydroxide ion-conducting electrolytes in energy conversion applications. We selectively modified the interlayer and external surfaces of MgAl LDHs with tris(hydroxymethyl)aminomethane (TRIS) ligands. By adjusting the concentration of the TRIS surface modifier, the LDH basal plane surfaces could be functionalized everywhere (internally and externally) or only externally. External modification resulted in loss of OH-conductivity compared to pristine LDHs, confirming that external platelet surfaces are the primary ion conduction pathway.

Hydrochemical characterization and comprehensive water quality assessment of groundwater within the main stream area of Yishu River.

To gain a comprehensive understanding of the hydrochemical characteristics, controlling factors, and water quality of groundwater in the main stream area of Yishu River (MSYR), a study was conducted using water quality data collected during both the dry and wet seasons. Through statistical analysis, hydrochemical methods, fuzzy comprehensive evaluation, and health risk evaluation modeling, the water chemical characteristics of the main stream area of Yishu River were studied, and the water quality of the area was comprehensively evaluated. The findings indicate that HCO3- and Ca2+ are the predominant anions and cations in the MSYR during the dry and wet seasons, respectively. Moreover, anion concentration in groundwater follows HCO3- > SO42- > NO3- > Cl-, while cations are ranked as Ca2+ > Na+ > Mg2+ > K+. Overall, the groundwater manifests as weakly alkaline and is predominantly classified as hard-fresh water. During the wet season, there is greater groundwater leaching and filtration, with rock and soil materials more readily transferred to groundwater, and the concentrations of main chemical components in groundwater are higher than those during the dry season, and the hydrochemical types are primarily characterized as HCO3-Ca·Mg and SO4·Cl-Ca·Mg types. These results also suggest that the chemical composition of the groundwater in the MSYR is influenced mainly by water-rock interaction. The primary ions originate from the dissolution of silicate rock and carbonate rock minerals, while cation exchange plays a critical role in the hydrogeochemical process. Groundwater in the MSYR is classified mostly as class II water, indicating that it is generally of good quality. However, areas with high levels of class IV and V water are present locally, and NO3- concentration is a crucial factor affecting groundwater quality. In the wet season, more groundwater and stronger mobility lead to greater mobility of NO3- and wider diffusion. Therefore, the risk evaluation model shows that nitrate health risk index is higher in the wet season than it is in the dry season, with children being more vulnerable to health risks than adults. To study groundwater in this area, its hydrochemical characteristics, water quality, and health risk assessment are of great practical significance for ensuring water safety for residents and stable development of social economy.

ToF-SIMS spectra of historical inorganic pigments: Lead-based pigments in positive polarity

ToF-SIMS is increasingly used to analyze cultural heritage materials because it can simultaneously detect organic and inorganic materials while mapping them on a surface. The precise identification of a pigment in a specific layer of a painting or of remaining color on a statue can inform about the technique used or the time of manufacture as well as expose possible forgeries when anachronistic ingredients are identified. Reference spectra are required to confidently identify a given pigment using ToF-SIMS. This database focuses on eight lead-based historical inorganic pigments, manufactured following traditional recipes. Lead pigments have been widely used in painting until the late 19th century. Here, the positive polarity ToF-SIMS reference spectra using a Bi3+ primary ion species are presented.

UPLC-Q-TOF-MSE Based Profiling of the Chemical Composition of Different Parts of Tetrastigma hemsleyanum

Objectives: The differences in chemical constituents in different parts of Tetrastigma hemsleyanum were analyzed. Methods: The contents of total phenols, total flavonoids, and polysaccharides in methanol extracts from different parts of T. hemsleyanum in Zhejiang were determined, and the chemical components of different parts of T. hemsleyanum were collected by ultra-performance liquid chromatography-tandem quadrupole-time-of-flight mass spectrometry. The differential index components of different parts of T. hemsleyanum were identified and analyzed by accurate mass-to-charge ratio of primary mass spectrometry and fragment ion of secondary mass spectrometry with reference spectrum and software database search and related literature reports. Results: A total of 20 components were identified, including 13 identified in root tubers, 7 in fibrous roots and 8 in leaves, and the structural cleavage of its compounds was analyzed. Conclusion: It provides a possibility and theoretical basis for the future use of the whole plant of T. hemsleyanum as medicine.

Parameterization of Secondary Ionization Rates and Photoelectron Heating Rates of Venus and Mars

AbstractAs a fundamental physical process in the ionosphere, photoionization and the associated photoelectrons play vital roles in determining the ionospheric electron density and temperature for Earth and other planets with atmospheres such as Mars and Venus. The production and transport of ionospheric photoelectrons have been widely examined on Earth, but relatively less studied for other terrestrial planets, such as Mars and Venus. In this study, a two‐stream photoelectron transport model for Mars and Venus is constructed, in which the photoelectron fluxes, photoelectron heating rates, primary and secondary ionization rates are calculated. The simulated photoelectron fluxes agree with Mars Atmosphere and Volatile Evolution (MAVEN) observations at various altitudes, with the input of solar spectrum irradiance, electron density and temperature, neutral density and temperature observed by MAVEN. Moreover, by parametrically fitting the simulation results for various solar zenith angles and solar activities, we obtain empirical parameterized formulas for ionization and heating efficiencies which can potentially be adapted to planetary ionospheric models for the community.