Quantitative Secondary Ion Mass Spectrometry Research Articles

16O-rich anhydrous silicates in CI chondrites: Implications for the nature and dynamics of dust in the solar accretion disk

CI chondrites have nonvolatile chemical compositions closely resembling that of the Sun’s photosphere and are thus considered to have the most primitive compositions of all known solar system materials. They have, however, experienced pervasive parent-body alteration processes that transformed their primary constituents, obscuring the nature and origin of primordial CI dust. We used in-situ quantitative microprobe and secondary ion mass spectrometry techniques to characterize the chemistry and oxygen isotopic compositions of anhydrous silicates in two sections of the CI chondrites Ivuna and Alais, which contain higher abundances of those than other CI samples. These silicates are Mg-rich olivine and low-Ca pyroxene crystals mostly occurring as aggregates within sub-mm Fe-rich clasts. Our data reveal mass-independent oxygen isotopic variations with Δ17O values ranging from −23.63 to −0.57‰, representing the first evidence of extremely 16O-rich (Δ17O < −20‰) olivine and pyroxene grains in CI chondrites. Two of these olivines are characterized by MnO/FeO ∼ 1, typical of low-iron, Mn-enriched silicates commonly observed in amoeboid olivine aggregates. Other anhydrous silicate grains have Δ17O values ranging from −6 to 0‰, probably representing chondrule fragments. Combined, these results indicate that chondrule and refractory inclusion material were incorporated into the CI parent body(ies). This conclusion is consistent with recent models showing that refractory inclusions could have formed and/or been transported at larger heliocentric distances than previously thought during the concomitant injection of material from the molecular cloud and outward extension of the disk by viscous spreading. The CI chondrules are presumably of local origin, with their isotopic systematics suggesting an affinity with the CR clan.

Spinel in CV chondrules: Investigating precursor legacy and chondrule thermal histories

AbstractIn carbonaceous chondrites, Mg‐spinel (MgAl2O4) grains are ubiquitous in refractory inclusions but rarely reported in chondrules, where they may correspond to minerals either (i) inherited from chondrule precursors or (ii) crystallized from chondrule melts. Here, we report high‐current quantitative electron microprobe measurements and secondary ion mass spectrometry oxygen isotopic analyses of Mg‐spinel‐bearing chondrules in the CV3 carbonaceous chondrites Northwest Africa 10235 and Allende. Compared to spinels in refractory inclusions, chondrule spinels are characterized by higher Cr contents and 16O‐poorer oxygen isotopic signatures (∆17O ≡ δ17O−0.52 × δ18O, from −2 to −6‰). Because the similar Δ17O values of chondrule olivine and spinel crystals imply their comagmatic origin, we applied a geothermometer based on the Al‐Cr distribution between these minerals to determine their crystallization temperatures. The calculated temperatures range from 1200 to 1640 °C (mean = 1470 °C), most being lower than the estimated liquidus temperature of porphyritic chondrules (~1600 °C). Our results suggest that chondrules experienced relatively slow cooling rates (slower than a few hundreds of °C h−1), which is in good agreement with models of chondrule formation invoking nonlinear or two‐stage cooling rates.

Insight into structure-property relationship of organometallic terpyridine wires: Combined theoretical and experimental study

Recent development in combined theoretical and experimental analysis methods offer an attractive opportunity to investigate organometallic materials. The selection of optimally combined characterization techniques allows for an effective description and even prediction of structure-property relationship occurring in terpyridine (TPY) molecules. In this work, secondary ion mass spectrometry (SIMS), quantitative and qualitative characterization, hand-in-hand, with density functional theory (DFT) calculations, can aid analysis of the chemical stability and reactivity of organic compounds. A case study was based on the characterization of [M-(TPY)2]2+ complexes (M: Co/Fe) with specific organic and organometallic architectures. The SIMS mass spectra showed the step-by-step molecules fragmentation and the quantitative SIMS analysis allowed to predict its direction. Analysis of electron density, electrostatic potential visualization, and calculated bonds length and HOMO-LUMO energetic gap were employed to confirm the differences between the bond-breaking mechanism depending on the metal atom bound to the terpyridine. The combined DFT/SIMS approach was successfully used to assess the chemical stability of various isomers of the TPY compounds, and to determine the possible fragmentation pathways depending largely on the metal centre present within the TPY structure.

Heterotrophic Foraminifera Capable of Inorganic Nitrogen Assimilation.

Nitrogen availability often limits biological productivity in marine systems, where inorganic nitrogen, such as ammonium is assimilated into the food web by bacteria and photoautotrophic eukaryotes. Recently, ammonium assimilation was observed in kleptoplast-containing protists of the phylum foraminifera, possibly via the glutamine synthetase/glutamate synthase (GS/GOGAT) assimilation pathway imported with the kleptoplasts. However, it is not known if the ubiquitous and diverse heterotrophic protists have an innate ability for ammonium assimilation. Using stable isotope incubations (15N-ammonium and 13C-bicarbonate) and combining transmission electron microscopy (TEM) with quantitative nanoscale secondary ion mass spectrometry (NanoSIMS) imaging, we investigated the uptake and assimilation of dissolved inorganic ammonium by two heterotrophic foraminifera; a non-kleptoplastic benthic species, Ammonia sp., and a planktonic species, Globigerina bulloides. These species are heterotrophic and not capable of photosynthesis. Accordingly, they did not assimilate 13C-bicarbonate. However, both species assimilated dissolved 15N-ammonium and incorporated it into organelles of direct importance for ontogenetic growth and development of the cell. These observations demonstrate that at least some heterotrophic protists have an innate cellular mechanism for inorganic ammonium assimilation, highlighting a newly discovered pathway for dissolved inorganic nitrogen (DIN) assimilation within the marine microbial loop.

Analysis of useful ion yield for Si in GaN by secondary ion mass spectrometry

The optimum detection levels that can be achieved by a secondary ion mass spectrometer are dependent on how efficiently a particular species of interest can be ionized and detected. One can determine in advance whether the analysis of a particular ion in the sample is possible, if the useful ion yield is known. The useful ion yield depends on the element, instrument transmission, the analytical conditions, the sample matrix, etc. The value of the useful ion yield for a species can diverge from one instrument type to another due to its different transmission and ionization probabilities. However, the same tendencies in the results may be expected for all types of instruments. In this paper, the authors present a quantitative secondary ion mass spectrometry analysis of the useful ion yield for the silicon dopant species in a gallium nitride matrix grown by metal organic chemical vapor deposition. Positively ionized cesium was used as the primary ion beam, and its energy was varied in the range from 0.5 to 5 kV. A quadrupole mass analyzer was utilized to collect secondary ion species of interest. The analysis results can be used to determine the primary beam energies for optimal Si sensitivity.

Analysis of useful ion yield for the Mg dopant in GaN by quadrupole—SIMS

The authors present a quantitative secondary ion mass spectrometry (SIMS) analysis of the useful ion yield of magnesium dopant in a gallium nitride matrix. A quadrupole SIMS instrument was used to analyze an Mg-doped GaN sample grown by metal organic chemical vapor deposition. Oxygen (O2+) was used as the primary ion beam and its energy was varied in the range from 0.5 to 5 kV with and without oxygen flooding near the sample. The results of the analysis can be used to determine the primary beam energies for optimal magnesium sensitivity.

Quantitative SIMS Imaging of Agar-Based Microbial Communities

After several decades of widespread use for mapping elemental ions and small molecular fragments in surface science, secondary ion mass spectrometry (SIMS) has emerged as a powerful analytical tool for molecular imaging in biology. Biomolecular SIMS imaging has primarily been used as a qualitative technique; although the distribution of a single analyte can be accurately determined, it is difficult to map the absolute quantity of a compound or even to compare the relative abundance of one molecular species to that of another. We describe a method for quantitative SIMS imaging of small molecules in agar-based microbial communities. The microbes are cultivated on a thin film of agar, dried under nitrogen, and imaged directly with SIMS. By use of optical microscopy, we show that the area of the agar is reduced by 26 ± 2% (standard deviation) during dehydration, but the overall biofilm morphology and analyte distribution are largely retained. We detail a quantitative imaging methodology, in which the ion intensity of each analyte is (1) normalized to an external quadratic regression curve, (2) corrected for isomeric interference, and (3) filtered for sample-specific noise and lower and upper limits of quantitation. The end result is a two-dimensional surface density image for each analyte. The sample preparation and quantitation methods are validated by quantitatively imaging four alkyl-quinolone and alkyl-quinoline N-oxide signaling molecules (including Pseudomonas quinolone signal) in Pseudomonas aeruginosa colony biofilms. We show that the relative surface densities of the target biomolecules are substantially different from values inferred through direct intensity comparison and that the developed methodologies can be used to quantitatively compare as many ions as there are available standards.

Invisible gold in arsenian pyrite from the high-grade Hishikari gold deposit, Japan: Significance of variation and distribution of Au/As ratios in pyrite

Au and As concentrations in pyrite grains from the Hishikari deposit were extensively determined by secondary ion mass spectrometry (SIMS) and electron probe microanalysis (EPMA) to investigate the microscale relationship between Au and As. The low-sulfidation epithermal Hishikari deposit, which has produced more than 224 t of gold since 1985 (as of March 2016), is world-famous for its high-grade ore. Accurate quantitative SIMS analyses of Au in pyrite were possible by preparing an Au-implanted pyrite standard sample and by using a properly tuned SIMS analytical method. An analysis size of 3 μm was chosen since the pyrite grains from the Hishikari deposit have heterogeneous As concentrations. This paper presents the first comprehensive data set of Au and As concentrations in a 3 μm area of pyrite obtained from the widely distributed high-grade Au-bearing Hishikari veins.Microanalyses of arsenian pyrite from the Hishikari gold deposit by SIMS and EPMA revealed that Au concentrations of 0.1–2800 ppm are positively correlated with As concentrations of 0 to 7 wt% in a 3 μm area. The formation of Hishikari veins is divided into two stages that are further subdivided into the early and late sub-stages. The rim of a pyrite grain precipitates after formation of the core; however, the time scale of core and rim formation is far shorter than that of the entire mineralization sequence. The specific value of the Au/As ratio in pyrite proves to be characteristic of the specific Au-bearing vein and its specific depth. Therefore, it could be possible to infer the nature of unknown veins by the Au/As ratio obtained. Although the Au/As ratio varies from vein to vein, a general tendency is observed for each ore zone of the Hishikari deposit. The Au/As ratio is high in the Sanjin ore zone, which consists of numerous high-grade veins in or above the Cretaceous accretionary sedimentary rocks of the Shimanto Group. The Au/As ratio is moderate in the Honko ore zone, which consists of several high-grade veins and also occurs in or above the basement sedimentary rocks. On the other hand, the Yamada ore zone, which consists of relatively low-grade veins, occurs in Pleistocene andesitic pyroclastic rocks that overlie the basement sedimentary rocks unconformably. The Au/As ratio in pyrite of the Yamada ore zone is relatively low compared with that of other ore zones.Several previous papers have proposed that the As− in pyrite may contribute to the reduction of Au+ to Au0 as Au nanoparticles (NPs) by As oxidation; however, Au and As concentrations of arsenian pyrites fall on or below the Au solubility limit in this study. Moreover, the As and S concentrations in pyrite are inversely correlated, which is consistent with the substitution of As for S as anionic As− in the Fe(S1−xAsx)2 solid solution of natural arsenian pyrite under reducing environments. The present study suggests that the Hishikari Au exists as a solid solution in the Hishikari arsenian pyrite, although there remains a possibility that it exists partially in the form of NPs even though the Au and As concentrations of arsenian pyrites fall on or below the Au solubility limit.

Quantitative SIMS depth profiling of Al in AlGaN/AlN/GaN HEMT structures with nanometer-thin layers

The possibilities of quantitative secondary ion mass spectrometry (SIMS) depth profiling of Al in AlxGa1 − xN/AlN/GaN transistor heterostructures are shown. Using a series of test structures for a TOF.SIMS-5 time-of-flight mass spectrometer, we obtained a refined linear calibration dependence of the secondary-ion yield on the composition ×, namely, Y(CsAl+)/Y(CsGa+) = K × x/(1 − x), with a high linear correlation coefficient, Rl = 0.9996, which permits quantitative SIMS analysis of relatively thick AlGaN barrier layers. The method of profile reconstruction with allowance for the main artifacts of ion sputtering has been first applied for the analysis of GaN/AlGaN/AlN/GaN high electron mobility transistor structure. This method permits to perform quantitative analysis of the thickness and composition of a nanometer-thin AlN sublayer and to estimate the measurement error. For the structure being studied, the AlN sublayer is 1.2 ± 0.2 nm thick. Copyright © 2016 John Wiley & Sons, Ltd.

Matrix effects in biological SIMS using cluster ion beams of different chemical composition.

The influence of the matrix effect on secondary ion yield presents a very significant challenge in quantitative secondary ion mass spectrometry (SIMS) analysis, for example, in determining the relative concentrations of metabolites that characterize normal biological activities or disease progression. Not only the sample itself but also the choice of primary ion beam may influence the extent of ionization suppression/enhancement due to the local chemical environment. In this study, an assessment of ionization matrix effects was carried out on model systems using C60 (+), Arn (+), and (H2O)n (+) cluster ion beams. The analytes are pure and binary mixtures of amino acids arginine and histidine biological standards. Ion beams of 20 keV were compared with a range of cluster sizes n = 1000-10 000. The component secondary ion yields were assessed for matrix effects using different primary ion beams and sample composition. The presence of water in the cluster beam is associated with a reduction in the observed matrix effects, suggesting that chemically reactive ion beams may provide a route to more quantitative SIMS analysis of complex biological systems.

&amp;quot;MS-Patch-Clamp&amp;quot; or the Possibility of Mass Spectrometry Hybridization with Patch-Clamp Setups for Single Cell Metabolomics and Channelomics

In this projecting work we propose a mass spectrometric patch-clamp equipment with the capillary performing both a local potential registration at the cell membrane and the analyte suction simultaneously. This paper provides a current literature analysis comparing the possibilities of the novel approach proposed with the known methods, such as scanning patch-clamp, scanning ion conductance microscopy, patch clamp based on scanning probe microscopy technology, quantitative subcellular secondary ion mass spectrometry or "ion microscopy", live single-cell mass spectrometry, in situ cell-by-cell imaging, single-cell video-mass spectrometry, etc. We also consider the ways to improve the informativeness of these methods and particularly emphasize the trend at the increasing of the analysis complexity. We propose here the way to improve the efficiency of the cell trapping to the capillary during MS-path-clamp, as well as to provide laser surface ionization using laser trapping and tweezing of cells with the laser beam transmitted through the capillary as a waveguide. It is also possible to combine the above system with the microcolumn separation system or capillary electrophoresis as an optional direction of further development of the complex of analytical techniques emerging from the MS variation of patch-clamp.

A new application of SIMS to the analysis of nitrogen in mica minerals: tobelite

Muscovite, KAl2[AlSi3O10](OH)2, is a common rock-forming mineral in igneous and metamorphic-rocks, sediments, hydrothermal alteration and ore deposits. The site between two adjacent T-O-T (tetrahedral-octahedral-tetrahedral) layers is shared between K and NH4 in all proportions leading to the building of the "ammonium micas". In this work three tobelite crystals were investigated in terms of major and minor constituents by electron probe microanalysis (EPMA) and in terms of nitrogen, for the first time at authors' knowledge, by secondary ion mass spectrometry (SIMS). The objective was that to gain information on the presence and amount of NH4 in this matrix. The lack of standards did not allow us to provide quantitative results at the ion microprobe. Nevertheless, the SIMS data agree qualitatively with constraints resulting from EPMA analyses and charge-balance crystal chemical considerations. The results of this study emphasize the capabilities of SIMS in the in-situ analysis of N and point out the possibility to develop reference materials (standards) for quantitative SIMS analysis of nitrogen in mica.

Studying femtosecond-laser hyperdoping by controlling surface morphology

We study the fundamental properties of femtosecond-laser (fs-laser) hyperdoping by developing techniques to control the surface morphology following laser irradiation. By decoupling the formation of surface roughness from the doping process, we study the structural and electronic properties of fs-laser doped silicon. These experiments are a necessary step toward developing predictive models of the doping process. We use a single fs-laser pulse to dope silicon with sulfur, enabling quantitative secondary ion mass spectrometry, transmission electron microscopy, and Hall effect measurements. These measurements indicate that at laser fluences at or above 4 kJ m−2, a single laser pulse yields a sulfur dose &amp;gt;(3 ± 1) × 1013 cm−2 and results in a 45-nm thick amorphous surface layer. Based on these results, we demonstrate a method for hyperdoping large areas of silicon without producing the surface roughness.

Quantitative SIMS Analysis of Biological Mixtures with Fast Heavy Ion Irradiation

We have investigated the secondary ion emission from arginine amino acid thin films under fast heavy ion irradiation using the time-of-flight technique. In a previous study, we reported on the high yield of arginine ions and low relative intensities of fragment ions compared to 10 keV Ar+ irradiation. These features would be useful for identification of biological mixtures. In this work, we measured secondary ion yields from mixed samples of the drug ipratropium bromide (IB) and cholesterol at various concentrations under 6 MeV Cu4+ irradiation. We detected molecular-related ions of IB from mixture films composed of a molar ratio of 0.33% IB to cholesterol at high sensitivity. The yield ratios of IB ions to cholesterol ions showed linear dependence on the molar concentration ratios of IB to cholesterol. These results indicate that secondary ion mass spectrometry (SIMS) using high-energy ions is useful for quantitative microanalysis of drugs in real biological samples.

Mass fractionation of carbon and hydrogen secondary ions upon Cs+ and O2+ bombardment of organic materials

A phenomenon known as mass fractionation has been probed in organic materials using secondary ion mass spectrometry (SIMS). Mass fractionation occurs because two isotopes of a particular species (i.e., identical number of protons, but different number of neutrons) do not have identical secondary ion yields in a constant chemical environment. Two primary ion probes, Cs+ and O2+, have been utilized with detection of negative and positive secondary ions, respectively, using a magnetic sector mass spectrometer. These two analysis conditions have been found to yield considerably different mass fractionation effects as a result of different sputtering and ionization mechanisms. Also, as determined previously with SIMS analysis of inorganic materials, the lower molecular weight species carbon and hydrogen are particularly susceptible to mass fractionation effects. Because organic materials are primarily composed of carbon and hydrogen, and because isotopic labeling is often utilized to accurately analyze such materials, knowledge of these effects in organic materials is essential for quantitative SIMS analysis.

In situ oxygen incorporation and related issues in CdTe∕CdS photovoltaic devices

Cd Te ∕ Cd S ∕ Sn O 2 ∕ ITO : F solar cell devices were investigated using quantitative secondary ion mass spectrometry (SIMS) depth profiling. They were grown on sapphire substrates and potentially active impurity species were analyzed. The SIMS data were calibrated for both CdS window layer (grown by sputtering) and CdTe absorber layer (deposited by close-space sublimation). For comparison, some of the samples were grown with and without oxygen incorporation into the CdTe layer during its deposition, and with and without postgrowth cadmium chloride (CdCl2) annealing in air and chemical etching. These devices were back contacted using Mo∕Sb2Te3 sputtered layers. It was shown that for CdTe and CdS layers there was a correlation between the concentrations of oxygen and chlorine. In situ oxygen incorporation in the CdTe layer yielded a substantial improvement in the device parameters and achieved an efficiency of 14% compared to 11.5% for devices fabricated in the same conditions without oxygen incorporation in CdTe. In light of our previous reports, this study also led to a clear determination of the origin of Na and Si traces found in these devices.

SIMS depth profiling of CdTe-based solar cells grown on sapphire substrates

CdTe/CdS/TCO solar cell structures were grown on sapphire substrates especially to investigate the impurity distributions in them. The study was performed using quantitative secondary ion mass spectrometry (SIMS) depth profiling, from the CdTe back surface through to the TCO layer. The species investigated were F, Br, Na, Si, Sn, In, O, Cl, S and Te, and for the purpose of comparison, some of the structures were investigated in their as-grown state. It has been shown that while Si concentration profiles are similar to those for structures grown on glass, Na was more than one order of magnitude lower when sapphire was used as substrate instead of glass. This demonstrates that Na diffused from the glass substrate. Moreover, the overall Na concentration in structures with and without CdCl 2 treatment showed that Na also originated from the CdCl 2, which is in accordance with our recently reported studies of impurities in CdCl 2. The concentration of Br was found to be at least 10 times higher in the etched structures compared to the un-etched ones, especially near the CdTe surface where there was a clearly resolved diffusion profile. In the CdTe active layer, the concentration of F was about 4 × 10 15 cm − 3 with a relatively flat level but with surface segregation following heat treatment. Finally, the potential diffusion of Sn and In from the sputtered SnO 2/ITO:F TCO layer into the CdTe active layer was investigated. It was found that there was no measurable diffusion of Sn from the SnO 2 layer into CdTe. Moreover, the SnO 2 layer played an important role in preventing the diffusion of In from the In-containing TCO layer.

Efficiency improvement in thin-film solar cell devices with oxygen-containing absorber layer

The CdTe∕CdS solar cell devices were grown using a dry process consisting of sputtering for the transparent conducting oxide and CdS window layers, and close-space sublimation for CdTe absorber layer. These devices were back contacted using Mo∕Sb2Te3 sputtered layers following the CdCl2 activation process carried out in air. It was shown that when oxygen is intentionally introduced in the CdTe layer during its growth, this leads to a significant improvement in all the device parameters yielding an efficiency of 14% compared to 11.5% for devices fabricated in the same conditions but without intentional oxygen incorporation in CdTe. The data obtained were not altered following a light soaking. The devices were investigated by quantitative secondary ion mass spectrometry, which allowed insight into the distribution and amount of oxygen and chlorine within the entire device structure. Both impurities showed an increased concentration throughout the CdTe absorber layer.

Role of substrate and transparent conducting oxide in impurity evolvement in polycrystalline thin-film devices

A comparison of as-grown and processed CdTe∕CdS solar cell structures deposited on sapphire substrate has been undertaken with those grown on glass. The device structures were depth-profiled using quantitative secondary ion mass spectrometry. It was shown that while Si concentration profiles are similar to those for structures grown on glass, Na was more than one order of magnitude lower when sapphire was used instead of glass, showing that Na diffused from the glass. It was also found that there was no measurable diffusion of Sn from the SnO2 layer into CdTe, and that the former played an important role in preventing the diffusion of In from In-containing transparent conducting oxide layer. Cl, O, Br, and F species were also investigated and while Cl and O were found to be independent of the nature of the substrate used, Br and F were shown to be affected by the processing.

The quantitative analysis of OH in vesuvianite: a polarized FTIR and SIMS study

A well-characterized suite of vesuvianite samples from the volcanic ejecta (skarn or syenites) from Latium (Italy) was studied by single-crystal, polarized radiation, Fourier-transform infrared (FTIR) spectroscopy and secondary-ion mass-spectrometry (SIMS). OH-stretching FTIR spectra consist of a rather well-defined triplet of broad bands at higher-frequency (3,700–3,300 cm−1) and a very broad composite absorption below 3,300 cm−1. Measurements with E//c or E⊥c show that all bands are strongly polarized with maximum absorption for E//c. They are in agreement with previous band assignments (Groat et al. Can Mineral 33:609, 1995) to the two O(11)–H(1) and O(10)–H(2) groups in the structure. Pleochroic measurements with changing direction of the E vector of the incident radiation show that the orientation of the O(11)–H(1) dipole is OH∧c~35°, in excellent agreement with the neutron data of Lager et al. (Can Mineral 37:763, 1999). A SIMS-based calibration curve at ~10% rel. accuracy has been worked out and used as reference for the quantitative analysis of H2O in vesuvianite by FTIR. Based on previous SIMS results for silicate minerals (Ottolini and Hawthorne in J Anal At Spectrom 16:1266, 2001; Ottolini et al. in Am Mineral 87:1477, 2002) the SiO2 and FeO content of the matrix were assumed as the major factors to be considered at a first approximation in the selection of the standards for H. The lack of vesuvianite standards for quantitative SIMS analysis of H2O has been here overcome by selecting low-silica elbaite crystals (Ottolini et al. in Am Mineral 87:1477, 2002). The resulting integrated molar absorption FTIR coefficient for vesuvianite is e i =100.000±2.000 l mol−1 cm−2. SIMS data for Li, B, F, Sr, Y, Be, Ba REE, U and Th are also provided in the paper.