Combination Of Secondary Ion Mass Spectrometry Research Articles

Atomistic simulations for investigation of substrate and salt effects on lipid in-source fragmentation in secondary ion mass spectrometry: A follow-up study.

In-source fragmentation (ISF) poses a significant challenge in secondary ion mass spectrometry (SIMS). These fragment ions increase the spectral complexity and can lead to incorrect annotation of fragments as intact species. The presence of salt that is ubiquitous in biological samples can influence the fragmentation and ionization of analytes in a significant manner, but their influences on SIMS have not been well characterized. To elucidate the effect of substrates and salt on ISF in SIMS, we have employed experimental SIMS in combination with atomistic simulations of a sphingolipid on a gold surface with various NaCl concentrations as a model system. Our results revealed that a combination of bond dissociation energy and binding energy between N-palmitoyl-sphingomyelin and a gold surface is a good predictor of fragment ion intensities in the absence of salt. However, ion-fragment interactions play a significant role in determining fragment yields in the presence of salt. Additionally, the charge distribution on fragment species may be a major contributor to the varying effects of salt on fragmentation. This study demonstrates that atomistic modeling can help predict ionization potential when salts are present, providing insights for more accurate interpretations of complex biological spectra.

Imaging and Manipulation of Plasma Membrane Fatty Acid Clusters Using TOF-SIMS Combined Optogenetics.

The plasma membrane (PM) serves multiple functions to support cell activities with its heterogeneous molecular distribution. Fatty acids (FAs) are hydrophobic components of the PM whose saturation and length determine the membrane's physical properties. The FA distribution contributes to the PM's lateral heterogeneity. However, the distribution of PM FAs is poorly understood. Here, we proposed the FA cluster hypothesis, which suggested that FAs on the PM exist as clusters. By the optogenetic tool translocating the endoplasmic reticulum (ER), we were able to manipulate the distribution of PM FAs. We used time-of-flight combined secondary ion mass spectrometry (TOF-SIMS) to image PM FAs and discovered that PM FAs were presented and distributed as clusters and are also manipulated as clusters. We also found the existence of multi-FA clusters formed by the colocalization of more than one FA. Our optogenetic tool also decreased the clustering degree of FA clusters and the formation probability of multi-FA clusters. This research opens up new avenues and perspectives to study PM heterogeneity from an FA perspective. This research also suggests a possible treatment for diseases caused by PM lipid aggregation and furnished a convenient tool for therapeutic development.

Evaluating zircon initial Hf isotopic composition using a combined SIMS–MC-LASS-ICP-MS approach: A case study from the Coompana Province in South Australia

The accessory mineral zircon is the most widely used geological timekeeper and tracer of crustal growth processes. Specifically, U–Pb isotopes in zircon offer a means to accurately determine the timing of magmatic events and their Hf isotopic composition provides a means to constrain magma source composition and potentially approximate source age. The high spatial resolution provided by in situ techniques such as secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have the advantage of being able to target different growth zones within individual zircon crystals, and unravel complex magmatic histories. However, utilising this power effectively requires calculation of accurate initial Hf compositions, which are founded on the assumption that the information obtained via the U–Pb and Lu–Hf systems are correctly integrated. A typical Hf isotope LA-ICP-MS analysis ablates a sample volume that is two orders of magnitude greater than a typical SIMS analysis. Thus, when age determination has been carried out by SIMS it is necessary to demonstrate that each subsequent Hf isotope analysis has sampled a similar isotopically homogeneous volume. Here, we use a combined SIMS and laser ablation split stream (LASS)-ICP-MS approach, whereby U–Pb isotopic measurement concurrently on the same sample volume as the Hf isotope measurement is compared to prior lower volume SIMS measurements. Using a suite of new drill core magmatic rock samples from the comparatively unexplored Coompana Province in South Australia, we demonstrate how such an approach can be used to filter Hf isotope datasets by identifying LASS-ICP-MS analyses that sampled mixtures of different zircon growth domains. The robust initial 176Hf/177Hf compositions obtained from the filtered Coompana data set indicate that the province represents part of a juvenile Paleoproterozoic-Mesoproterozoic arc system formed through hyper-extension of the margin of the Archean Gawler Craton. This arc system can be correlated to the Musgrave Province and Madura Province in central and Western Australia respectively.

Reprint Of: Enhanced spatially-resolved trace analysis using combined SIMS–single-stage AMS

Abstract Secondary ion mass spectrometry (SIMS) provides spatially resolved trace analysis of solid materials, but can be complicated by unresolved abundant molecular isobars. By adding a 300-kV single-stage accelerator mass spectrometer (SSAMS) as a detector for a Cameca ims 4f SIMS, one can measure more abundant positive ions from the SIMS while removing molecular isobars, thus improving very low abundance trace element and isotope analysis. This paper describes important features and capabilities of such an integrated system at the Naval Research Laboratory using charge state +1 ions. Transmission loss is compared to molecule destruction as gas flow to the molecule-destruction cell increases. As most measurements tolerate more modest abundance sensitivities than for 14C analysis, a lower gas flow is acceptable, so good transmission of 20–50% for ions of interest can be maintained for a broad range of ion masses. This new instrument has measured isotope ratios for uranium, lead, rare earths, and other elements from particulates and localized regions, with molecule destruction enabling the measurement at low SIMS mass resolving power and thus high transmission, as examples will show. This new and world-unique instrument provides improved capabilities for applications in nuclear and other forensics, geochemistry, cosmochemistry, and the development of optical, electronic, multifunctional, and structural materials.

Rapid, molecule-free, in situ rare earth element abundances by SIMS-SSAMS

We present a novel method for rapid and high-sensitivity in situ measurements of the rare earth elements (REEs) by combined secondary ion mass spectrometry and single-stage accelerator mass spectrometry (SIMS-SSAMS).

Enhanced spatially-resolved trace analysis using combined SIMS–single-stage AMS

Abstract Secondary ion mass spectrometry (SIMS) provides spatially resolved trace analysis of solid materials, but can be complicated by unresolved abundant molecular isobars. By adding a 300-kV single-stage accelerator mass spectrometer (SSAMS) as a detector for a Cameca ims 4f SIMS, one can measure more abundant positive ions from the SIMS while removing molecular isobars, thus improving very low abundance trace element and isotope analysis. This paper describes important features and capabilities of such an integrated system at the Naval Research Laboratory using charge state +1 ions. Transmission loss is compared to molecule destruction as gas flow to the molecule-destruction cell increases. As most measurements tolerate more modest abundance sensitivities than for 14C analysis, a lower gas flow is acceptable, so good transmission of 20–50% for ions of interest can be maintained for a broad range of ion masses. This new instrument has measured isotope ratios for uranium, lead, rare earths, and other elements from particulates and localized regions, with molecule destruction enabling the measurement at low SIMS mass resolving power and thus high transmission, as examples will show. This new and world-unique instrument provides improved capabilities for applications in nuclear and other forensics, geochemistry, cosmochemistry, and the development of optical, electronic, multifunctional, and structural materials.

High sensitivity and high resolution element 3D analysis by a combined SIMS-SPM instrument.

Using the recently developed SIMS–SPM prototype, secondary ion mass spectrometry (SIMS) data was combined with topographical data from the scanning probe microscopy (SPM) module for five test structures in order to obtain accurate chemical 3D maps: a polystyrene/polyvinylpyrrolidone (PS/PVP) polymer blend, a nickel-based super-alloy, a titanium carbonitride-based cermet, a reticle test structure and Mg(OH)2 nanoclusters incorporated inside a polymer matrix. The examples illustrate the potential of this combined approach to track and eliminate artefacts related to inhomogeneities of the sputter rates (caused by samples containing various materials, different phases or having a non-flat surface) and inhomogeneities of the secondary ion extraction efficiencies due to local field distortions (caused by topography with high aspect ratios). In this respect, this paper presents the measured relative sputter rates between PVP and PS as well as in between the different phases of the TiCN cermet.

Implantation, Diffusion, Activation, and Recrystallization of Gallium Implanted in Preamorphized and Crystalline Germanium

We investigated the as-implanted profiles, electrical activation, diffusion, and recrystallization of gallium implanted in germanium samples through the combination of secondary-ion mass spectrometry, transmission electron microscopy, and sheet resistance measurement. Because of their high activation level without preamorphization, low activation temperature , and absence of diffusion (up to ), Ga junctions in crystalline Ge are very promising candidates for implementation in germanium technology. In the amorphous Ge phase, an increased diffusivity of Ga was observed at temperatures above .

Nitrogen diffusion in doped TiO2 (110) single crystals: a combined XPS and SIMS study

Rutile TiO2 (110) single crystals were doped with nitrogen by heating at 675 °C in flowing NH3 gas. This caused a red shift in the band edge and an increase in visible region absorption. Nitrogen depth profiles obtained using dynamic secondary ion mass spectrometry (SIMS) could best be fitted by assigning three distinct diffusion coefficients. X-Ray photoelectron spectroscopy (XPS) indicated the presence of two surface nitrogen states with binding energies of 395.6 eV (substitutional N) and 399.8 eV (interstitial N). Angle resolved XPS measurements allowed us to link the XPS environments to the SIMS diffusion profiles. Subsequent air annealing at 500 °C led to asymmetric diffusion of the interstitial nitrogen into the bulk, removal of substitutional nitrogen into the gas phase, a decrease in the concentration of Ti3+ and a blue shift in the band edge. These changes could be related to variation in the optical band gap, and it was found that the principle cause of band gap narrowing was substitutional rather than interstitial nitrogen.

Depositional constraints and age of metamorphism in southern India: U–Pb chemical (EMPA) and isotopic (SIMS) ages from the Trivandrum Block

We report U–Pb electron microprobe (zircon and monazite) and Secondary Ion Mass Spectrometry (SIMS) U–Pb (zircon) ages from a granulite-facies metapelite and a garnet–biotite gniess from Chittikara, a classic locality within the Trivandrum Block of southern India. The majority of the electron-microprobe data on zircons from the metapelite define apparent ages between 1500 and 2500 Ma with a prominent peak at 2109±22 Ma, although some of the cores are as old as 3070 Ma. Zircon grains with multiple age zoning are also detected with 2500–3700 Ma cores, 1380–1520 mantles and 530–600 Ma outer rims. Some homogeneous and rounded zircon cores yielded late Neoproterozoic ages that suggest that deposition within the Trivandrum Block belt was younger than 610 Ma. The outermost rims of these grains are characterized by early Cambrian ages suggesting metamorphic overgrowth at this time. The apparent ages of monazite grains from this locality reveal multiple provenance and polyphase metamorphic history, similar to those of the zircons. In a typical case, Palaeoproterozoic cores (1759–1967 Ma) are enveloped by late Neoproterozoic rims (562–563 Ma), which in turn are mantled by an outermost thin Cambrian rim (∼515 Ma). PbO v. ThO*2 plots for monazites define broad isochrons, with cores indicating a rather imprecise age of 1913±260 Ma (MSWD=0.80) and late Neoproterozoic/Cambrian cores as well as thin rims yielding a well-defined isochron with an age of 557±19 Ma (MSWD=0.82). SIMS U–Pb isotopic data on zircons from the garnet–biotite gneiss yield a combined core/rim imprecise discordia line between 2106±37 Ma and 524±150 Ma. The data indicate Palaeoproterozoic zircon formation with later partial or non-uniform Pb loss during the late Neoproterozoic/Cambrian tectonothermal event. The combined electron probe and SIMS data from the metapelite and garnet–biotite gneiss at Chittikara indicate that the older zircons preserved in the finer-grained metapelite protolith have heterogeneous detrital sources, whereas the more arenaceous protolith of the garnet–biotite gniess was sourced from a single-aged terrane. Our data suggest that the metasedimentary belts in southern India may have formed part of an extensive late Neoproterozoic sedimentary basin during the final amalgamation of the Gondwana supercontinent.

A combined SIMS and ICPMS investigation of the origin and distribution of potentially electrically active impurities in CdTe/CdS solar cell structures

Quantitative, dynamic secondary ion mass spectrometry (SIMS) combined with inductively coupled plasma mass spectrometry (ICPMS) was used to study the origin and distribution of impurities in CdTe/CdS/In2O3:F/glass solar cell structures. Particular emphasis was put on the potentially electrically active impurities that may possibly originate from either the CdTe starting material or the cadmium chloride (CdCl2) post-deposition annealing-induced activation, and that are likely to affect the device performance. Structures were grown using CdTe starting material of 5N and 7N purity, and were analysed by SIMS, both before and after CdCl2 heat treatment. Depth profiles of the elements: Cl, O, Cu, Na, In, Sb, Sn, Si, Zn, Pb and S were made. Around 91% of the impurities detected by ICPMS in the CdCl2 powder used were found to consist of species known to show electrical activity in CdTe. The origin of most of the impurity species present in the cell structures was elucidated, and it was shown that Pb, Sn, Cu and Zn were not coming from the CdTe or CdCl2 starting materials. However, Na and Cl turned out to originate from the CdCl2 processing. The potential interdiffusion of elements, such as S, Te, Si, In and Na from the layers of the structures was also highlighted and is discussed.

Use of combined NAA and SIMS analyses for impurity level isotope detection

Neutron activation analysis (NAA) offers advantages for detecting impurity levels of select isotopes that have suitable neutron cross sections. Secondary ion mass spectrometry (SIMS) on the other hand detects most isotopes, but suffers various molecular interferences and covers only a small beam size volume per run. These two methods are combined here to study a large number of isotopes in titanium thin films in an electrolytic cell experiment. Nine isotopes are covered by NAA and over 50 with SIMS. An overlap in the data sets allows a normalization of SIMS data to the more accurate NAA measurements.

Deuterium accumulation in beryllium oxide layer exposed to deuterium atoms

The interaction of deuterium atoms with beryllium TIP-30 was studied at temperatures of 340, 500 and 740 K. After D atom exposure, the depth distributions of deuterium atoms and molecules in Be were measured using combined Secondary Ion Mass Spectrometry (SIMS) and Residual Gas Analysis (RGA) methods. It was shown that deuterium is mainly accumulated in the oxide layer although long tails are also observed. Deuterium is retained in two states – atomic and molecular forms. The amount of trapped deuterium in samples decreases during the sample storage in vacuum or air at room temperature. The results were explained by the chemical bonding of D atoms in BeO oxide with beryllium hydroxide formation and the trapping of deuterium molecules in bubbles which are formed at growth defects in the oxide layer.

Delta -function-shaped Sb-doping profiles in Si(001) obtained using a low-energy accelerated-ion source during molecular-beam epitaxy.

Two-dimensional (2D) buried \ensuremath{\delta}-function-shaped Sb-doping profiles have been obtained in Si using a low-energy accelerated Sb-ion source during molecular-beam epitaxy. A combination of secondary-ion mass spectrometry (SIMS), capacitance-voltage (C-V) measurements, and cross-sectional transmission electron microscopy (XTEM) was used to investigate dopant distributions and to determine profile widths. The 2D-sheet Sb-doping concentration ${\mathit{N}}_{\mathrm{Sb}}$, obtained by integrating SIMS \ensuremath{\delta}-doping profiles in samples grown with substrate temperature ${\mathit{T}}_{\mathit{s}}$=620 \ifmmode^\circ\else\textdegree\fi{}C and Sb-ion acceleration potentials ${\mathit{V}}_{\mathrm{Sb}}$=200 and 300 V, was found to vary linearly with the product of the Sb-ion flux and the exposure time (i.e., the ion dose) over the ${\mathit{N}}_{\mathrm{Sb}}$ range from 5\ifmmode\times\else\texttimes\fi{}${10}^{12}$ to 2\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. The full width at half maximum (FWHM) concentration of \ensuremath{\delta}-doping profiles in Si(001) films was less than the depth resolution of both SIMS and C-V measurements (\ensuremath{\sim}10 and 3 nm, respectively). High-resolution XTEM lattice images show that the FWHM was \ensuremath{\le}2 nm. This is consistent with dopant incorporation simulations, based upon a multisite transition-state dopant incorporation model, which show that accelerated-beam dopant species are trapped in near-surface substitutional sites with atomic mobilities between those of surface and bulk atoms. Dopant surface segregation during growth is strongly suppressed, and the dopant distribution is determined primarily by the straggle in ion trapping distributions. The present results are compared with profile broadening observed in \ensuremath{\delta}-doped layers obtained by solid-phase epitaxy of amorphous Si containing a buried Sb layer.

Combined SIMS/TPD investigations of UHV-prepared tolyltriazole overlayers on Cu, Ni and Au

The corrosion inhibitor tolyltriazole (TTA) has been investigated by combined secondary ion mass spectrometry (SIMS) and temperature programmed desorption mass spectrometry (TPD). TTA overlayers in the submonolayer to multilayer range are produced by in situ molecular beam exposure of Cu, Ni and Au substrates under UHV conditions. TPD yields information on different binding states and layer thickness. Molecular cluster ions as (2M−2H+Me) −, indicating the formation of TTA molecules in quasipolymeric chains, are emitted from all three substrates. Only for Cu we found a TTA desorption peak at high target temperatures (580 K), correlated to the emission of characteristic secondary ions, mainly (MH) − and (2M−2H+Cu) −. It is obviously the corresponding stable TTA monolayer on Cu that is responsible for the strong corrosion protection effect.

Oxygen adsorption on molybdenum studied by low-energy secondary-ion mass spectrometry and electron-induced desorption

The adsorption of oxygen on molybdenum in the monolayer region was studied using a combination of secondary-ion mass spectrometry (SIMS) at low primary energies and electron impact desorption. By examining the ion yields during adsorption and desorption at various temperatures, it was possible to identify two strongly bound states with activation energies for desorption of 120 and 107 kcal/mole. At room temperature, these $\ensuremath{\beta}$ states are populated first and afterwards there are at least two $\ensuremath{\alpha}$ states which are simultaneously filled. The desorption energies for the $\ensuremath{\alpha}$ states were estimated to be about 37 kcal/mole. One $\ensuremath{\alpha}$ state gives rise to electron-induced desorption of ${\mathrm{O}}_{e}^{+}$, the other does not. After only partial filling of the $\ensuremath{\alpha}$ states, a transformation of the state giving ${\mathrm{O}}_{e}^{+}$ could be observed at quite low temperatures (> 550\ifmmode^\circ\else\textdegree\fi{}K). The rate of transformation was greater, the lower the degree of occupation of the $\ensuremath{\alpha}$ states. The ${\ensuremath{\beta}}_{1}$, ${\ensuremath{\beta}}_{2}$, and $\ensuremath{\alpha}$ states have quite different influences on the SIMS ion yields. The formation of the oxide produces characteristic changes in ion yields. Secondary-ion energies were also measured. The value of low-energy SIMS in characterizing different states of adsorption is demonstrated.