Primary Ion Research Articles

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.

Evaluation of the pH and Antibacterial Efficacy of Mineral Trioxide Aggregate With and Without the Incorporation of Titanium Tetrafluoride.

Introduction Microorganisms play an important role in causing inflammation in the pulp and periapical regions. Even after undergoing chemo-mechanical procedures during root canal treatment, bacteria may persist within dentinal tubules, posing a risk of disease recurrence. Mineral trioxide aggregate (MTA), introduced as a dental material, has been investigated as a potential antibacterial agent since its early use. Calcium and phosphorus are the primary ions in MTA, and their antibacterial characteristics are attributed to the release of calcium hydroxide through surface hydrolysis of calcium silicate components. Previous studies have shown that MTA has limited antimicrobial properties. Several alterations have been made to enhance the biological properties of MTA, such as incorporating nanoparticles made from silver, zinc, gold, and titanium. Therefore, in this study, titanium tetrafluoride (TiF4) was added to MTA in an effort to enhance its antimicrobial properties. Aim To compare and evaluate the antibacterial efficacy of MTA after the incorporation of TiF4. Materials and methods A total of 56 samples were made by mixing MTA with different weight proportions of TiF4 (1 wt%, 2 wt%, and 3 wt%). Out of these, 28 samples were taken to test each of the following properties: antibacterial efficacy and pH. The specimens were prepared using stainless steel molds of recommended dimensions for testing the pH. The pH was evaluated using a pH meter, and the antibacterial efficacy was assessed using the direct contact test. Data regarding the antibacterial efficacy and pH of MTA with various proportions of TiF4 were investigated for normality using the Kolmogorov-Smirnov test and assessed for normal distribution. The antibacterial properties among the four groups were analyzed using one-way analysis of variance (ANOVA), followed by pairwise multiple comparisons using Tukey's Honest Significant Difference test. The level of statistical significance was determined at p ≤ 0.05. MTA, when incorporated with TiF4, showed enhanced antibacterial properties. Results On day 1, the group treated with MTA containing 3% TiF4 demonstrated the strongest antibacterial effectiveness, with a mean of 4.67 ± 0.04 colony-forming units (CFU)/mL × 10^8. However, the group treated with plain MTA had the lowest mean values, at 5.67 ± 0.25 CFU/mL × 10^8. On day 1, the MTA group with 3% TiF4 also had the highest mean pH values (11.90 ± 0.05), while the plain MTA group had the lowest mean pH values (11.64 ± 0.78). On day 7, the MTA group with 3% TiF4 had the highest pH value (12.85 ± 0.08), whereas the plain MTA group had the lowest pH value (11.92 ± 0.09). Conclusion The inclusion of TiF4 resulted in an augmentation of the antibacterial efficacy of MTA against Enterococcus faecalis (E. faecalis). Hence, the integration of TiF4 into MTA can be considered a promising development against E. faecalis during endodontic procedures.

Investigation of projectile fragment emission in the fragmentation of 28Si on C target at 736 A MeV

The emission angular distributions, the transverse momentum distributions and the temperature parameters of projectile fragments produced in fragmentation of [Formula: see text]Si on C target at 736[Formula: see text]A[Formula: see text]MeV are measured. It is found that the scattering angle of primary silicon ions is smaller than the emission angle of their fragments. The average value and the width of the angular distribution and the transverse momentum distribution are increased with the decrease of the charge of projectile fragments. The cumulative squared transverse momentum distribution of projectile fragments can be well fitted by a single Rayleigh distribution, which indicates that the projectile fragments are emitted from a single temperature emission source. Most of the temperature parameters of projectile fragments emission source are in the range of 2–5[Formula: see text]MeV, which does not obviously depend on the charge of the projectile fragments.

Heteroepitaxial growth of Ga2O3 thin films on Al2O3(0001) by ion beam sputter deposition

Deposition of epitaxial oxide semiconductor films using physical vapor deposition methods requires a detailed understanding of the role of energetic particles to control and optimize the film properties. In the present study, Ga2O3 thin films are heteroepitaxially grown on Al2O3(0001) substrates using oxygen ion beam sputter deposition. The influence of the following relevant process parameters on the properties of the thin films is investigated: substrate temperature, oxygen background pressure, energy of primary ions, ion beam current, and sputtering geometry. The kinetic energy distributions of ions in the film-forming flux are measured using an energy-selective mass spectrometer, and the resulting films are characterized regarding crystalline structure, microstructure, surface roughness, mass density, and growth rate. The energetic impact of film-forming particles on the thin film structure is analyzed, and a noticeable decrease in crystalline quality is observed above the average energy of film-forming Ga+ ions around 40 eV for the films grown at a substrate temperature of 725 °C.

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.

Time-Resolved Ion Mobility Spectrometry with a Stop Flow Confined Volume Reaction Region.

An ion source concept is described where the sample flow is stopped in a confined volume of an ion mobility spectrometer creating time-dependent patterns of ion patterns of signal intensities for ions from mixtures of volatile organic compounds and improved signal-to-noise rate compared to conventional unidirectional drift gas flow. Hydrated protons from a corona discharge were introduced continuously into the confined volume with the sample in air at ambient pressure, and product ions were extracted continuously using an electric field for subsequent mobility analysis. Ion signal intensities for protonated monomers and proton bound dimers were measured and computationally extracted using mobilities from mobility spectra and exhibited distinct times of appearance over 30 s or more after sample injection. Models, and experimental findings with a ternary mixture, suggest that the separation of vapors as ions over time was consistent with differences in the reaction rate for reactions between primary ions from hydrated protons and constituents and from cross-reactions that follow the initial step of ionization. The findings suggest that the concept of stopped flow, introduced here for the first time, may provide a method for the temporal separation of atmospheric pressure ions. This separation relies on ion kinetics and does not require chromatographic technology.

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.