Resolution Secondary Ion Mass Spectrometry Research Articles

Cellular internalization and intracellular biotransformation of silver nanoparticles in Chlamydomonas reinhardtii

It is necessary to elucidate cellular internalization and intracellular biotransformation in order to accurately assess the toxicity and fate of nanoparticles after interaction with organisms. Therefore, this work employed a combination of high resolution imaging and in situ detection spectroscopic techniques to systematically investigate the intracellular localization, morphology and chemical speciation of silver in the cells of Chlamydomonas reinhardtii, a unicellular freshwater green alga, after exposure to AgNPs coated with polyvinylpyrrolidone at a concentration of 2.0 mg/L. High resolution secondary ion mass spectrometry and high-angle annular dark field scanning transmission electron microscopy together with energy dispersive spectroscopy and selected area electron diffraction collectively confirmed that after 48 h of exposure, AgNPs entered the periplasmic space after cellular internalization into the algal cells. Silver was also found to coexist with sulfur inside the cytoplasm in both crystalline and amorphous forms, which were further identified as β-Ag2S and silver thiolates with synchrotron X-ray absorption spectroscopy. In combination, these analyses demonstrated that silver inside algae could be attributed to the uptake and sequestration of Ag+ ion released from AgNPs, which was further sequestrated into cellular compartments. This study provides solid evidence for particle internalization and biotransformation of AgNPs after interaction with algae.

Investigation of oxygen diffusion behavior in terbium using 18O2 isotopic tracking by high resolution SIMS

High resolution secondary ion mass spectrometry (SIMS) analysis has been used to study the oxidation mechanisms when high purity terbium (Tb) metal is exposed to corroding environments containing 18O2 isotope. The diffusion coefficients for 18O in Tb at a natural atmosphere can be calculated, which plays an important role in subsequent purification and application in industry. Clear evidence has been shown for the characteristic distributions of 18O after the kinetic transitions. The migration behavior is correlated with the existence of defects in the metal which allow the corrosions occur as localized nucleation. A set of ionization model has been developed to describe the oxidation process.

Migration of sulphur in thermal barrier coatings during heat treatment

The sulphur effect in thermal barrier coatings (TBCs) mainly refers to a segregation of sulphur at the interface between thermally grown oxide (TGO) and the bond coat, which significantly deteriorates scale adhesion to alloys. Restricted by the extremely low concentrations of sulphur (0–10ppm) in TBCs, previous investigations using conventional analytical techniques failed to provide a complete mechanism for the migration of sulphur. In this study, high resolution secondary ion mass spectrometry (NanoSIMS) was employed to detect trace sulphur distributions in commercial TBCs. After heat treatments, sulphur segregates at three typical areas in TBCs: (1) the yttria stabilized zirconia (YSZ) top coat; (2) the TGO/bond coat interface and (3) the grit blasted surface. This indicates that during heat treatment a significant outward diffusion of sulphur occurs from the superalloy to YSZ top coat through the TGO, and a possible mechanism for the migration of sulphur in TBCs is described. The undesired “sulphur effect” on scale adhesion was suggested to be caused by the formation of residual sulphides beneath the alumina scale with weaker ionic bonding to alloy cations. Possible solutions are suggested aiming to alleviate the sulphur effect in TBCs.

Decoding the oxygen isotope signal for seasonal growth patterns in Arctic bivalves

Chemical and physical variations in skeletal structures of marine organisms can reflect environmental variability, forming the basis for reconstructing the conditions in which the organism lived. The successful use of these bio-archives for reconstructing seasonal environmental conditions is dependent on understanding intra-annual growth patterns and timing of their deposition within skeletal structures. We studied intra-annual shell growth patterns, as well as the timing and environmental processes associated with winter growth line deposition in two circumpolar bivalve mollusks, Serripes groenlandicus and Ciliatocardium ciliatum. Shell growth deposited during a 1-year deployment on oceanographic moorings in Kongsfjorden and Rijpfjorden, Svalbard, was analyzed in situ for δ18O values using high spatial resolution secondary ion mass spectrometry (SIMS). A new digital method was developed to measure the location of SIMS spots along chronologically deposited shell material. Dynamic time warping algorithms were adapted to align SIMS-determined δ18O values with δ18O values predicted from continuous mooring instrument recordings of seawater temperature and salinity, in order to derive intra-annual shell growth models. The resulting growth models indicated that the prominent winter growth band was formed during a slow shell growth period lasting from December until May in Kongsfjorden and from November until mid-June in Rijpfjorden. The length of the slow growth period was most likely controlled by food availability. Shell growth rate during the growing season was significantly explained by temperature (marginal R2=0.29, p<0.001) indicating that temperature partly drives shell growth rate when the food supply is sufficient. The insights into intra-annual shell growth of Arctic bivalves and the methods developed in our study are important contributions for further development of bivalve shells as proxy archives.

On the effect of boron on grain boundary character in a new polycrystalline superalloy

The role of boron in conferring the grain boundary character in a new polycrystalline superalloy suitable for power generation applications is considered. One boron-free and three boron-containing variants are studied using a suite of high resolution characterisation techniques including atom probe tomography (APT), high resolution secondary ion mass spectroscopy (SIMS) and transmission electron microscopy (TEM). The primary effect of boron addition is the suppression of Cr-rich M23C6 carbide and the formation instead of the Cr-rich M5B3 boride. The SIMS analysis indicates that the boride particles are distributed fairly uniformly along the grain boundaries, of length up to 500 nm along the grain boundary. The substantial majority of the boron added resides in the form of these M5B3 borides; some boron segregation is found at the γ′/M5B3 interfaces but interfaces of other forms – such as γ/γ′, γ/M5B3, γ/MC and γ′/MC – show no significant segregation. Creep testing indicates that the optimum boron content in this alloy is 0.05 at.%.

Measurement and control of size and density of type-II ZnTe/ZnSe submonolayer quantum dots grown by migration enhanced epitaxy

For practical applications of self-assembled semiconductor quantum dots (QDs), it is important to control their densities and sizes, however these parameters are difficult to quantify. This is particularly challenging in case of submonolayer QDs, in spite of their remarkable features including absence of wetting layers and significantly small dimensions that are advantageous for many device application. We report here the investigation of submonolayer type-II ZnTe/ZnSe QDs grown via migration enhanced epitaxy (MEE) with varying Te content. The employment of MEE assists in the formation of QDs and facilitates improvement in overall material quality. The structural and optical properties of these QD structures were investigated using a variety of characterization tools. Low temperature photoluminescence measurement allowed for a good estimate of QD thicknesses, while observation of robust Aharanov–Bohm-oscillations in magneto-PL spectra was used to precisely determine diameters of these disc-shaped QDs. These results, in conjunction with high resolution x-ray diffraction and secondary ion mass spectrometry data of the Te concentration, were then used to evaluate the QD density. It is evident from the results that the dot density increases much faster than the QD size with respect to the increase in overall Te content. Most importantly, this study provides the dependence of average QD size and density as a function of Te flux and Te MEE cycles, and shows that these are the key parameters to control the QD dimension and distribution.

Mode and timing of granitoid magmatism in the Västervik area (SE Sweden, Baltic Shield): Sr–Nd isotope and SIMS U–Pb age constraints

Observed geochemical and geophysical signatures in the southern Svecofennian domain (SD) and the Transscandinavian Igneous Belt (TIB) are explained through a model of tectonic cycling and episodic south-westward migration of a subduction zone system. The Västervik area is located between these two major tectonic domains and as such has received much attention. Granitoids of the Västervik area were recently re-grouped and classified within the context of this larger regional tectonic model, but a discrepancy between previous relative age estimations and the few available granitoid age determinations was noted. To address this issue, we have dated 13 granitoid samples using a high spatial resolution secondary ion mass spectrometry (SIMS) U–Pb technique. Our new results constrain the intrusion of the majority of granitoids to 1819–1795 Ma, thus placing them into the TIB-1 period. This age range also encompasses our new ages from the central granodiorite belt and the Örö-Hamnö pluton, demonstrating a previous overestimation of older granitoid generations in the Västervik area. Nonetheless, it is shown that Askersund/TIB-0 magmatism, represented by an augen gneiss sample dated to 1846 Ma, is unambiguously present as far south as the Västervik region. The anatectically generated leucogranites reveal TIB-1 ages and, as expected, older inherited zircon derived from the parental metasedimentary Västervik formation. By simple Sr–Nd isotope modeling it is further possible to deduce that most TIB-1 granitoids follow a simple (assimilation-) fractional crystallization petrogenetic trend. The youngest granitoid generation was produced through low-pressure fluid-absent crustal melting. In conclusion, granitoids of the Västervik area fit well into the proposed model for south-westward migration of a subduction zone system active in the Svecofennian domain and represent a new tectonic cycle. It is therefore possible to link the Svecofennian domain and the Transscandinavian Igneous Belt within a single evolutionary scenario explaining the observed granitoid petrology, geochemistry and geochronology. The study area is located at the edge of a particularly long-lived active continental margin that started to operate during the supercontinent Columbia at ca. 1.8 Ga and the presented model explains how this margin initiated at its eastern end.

High resolution secondary ion mass spectrometry analysis of hydrogen behavior in SiO2/SiN/SiO2 films with thermal treatment

The distribution and behavior of hydrogen in a SiO2/SiN/SiO2 (ONO) film stack structure with thermal treatment were investigated by high-resolution secondary ion mass spectrometry analysis. Hydrogen atoms were present in the poly-Si/top-SiO2 interface, SiN layer, and bottom-SiO2/Si-substrate interface. These hydrogen atoms decreased in number with annealing (1000 °C, 60 s) and spike annealing (1000 °C, about 1 s). However, when a SiN cap layer with hydrogen atoms was formed on a poly-Si/ONO film structure, hydrogen atoms in the ONO film did not decrease in number with spike annealing. It was considered that the SiN cap layer mainly performed a supply source of hydrogen into the ONO film during spike annealing, and that hydrogen atoms interdiffused between the SiN cap layer and the SiN layer of the ONO film. These results indicate that the amount of hydrogen in the ONO film can be controlled by annealing and the formation of a SiN cap layer.

Neoproterozoic evolution of the eastern Arabian basement based on a refined geochronology of the Marbat region, Sultanate of Oman

Abstract New high spatial resolution secondary ion mass spectrometry (SIMS) U–Pb zircon data from the Sadh gneiss complex and the intruding Marbat granodiorite of the Marbat region, southern Sultanate of Oman, yield Cryogenian magmatic protolith ages for gneisses ranging from c. 850 to 830 Ma. Zircon ages record a c. 815–820 Ma period of deformation and migmatization, followed by intrusion of a hornblende gabbro/diorite and the undeformed Marbat granodiorite at c. 795 Ma. Following break-up and rifting of Rodinia at c. 870 Ma, crustal growth in the Marbat region occurred via arc accretion at c. 850–790 Ma, possibly in the easternmost part of the Mozambique Ocean based on earlier cessation of accretion here compared to the Arabian–Nubian Shield. Similarity of the new zircon geochronology to peaks of detrital zircon ages in the unconformably overlying Ediacaran Marbat sandstone suggests relatively local derivation from uplifted basement for the latter. Supplementary material: Detailed petrographic descriptions and photographs of hand specimens and thin-sections are available at http://www.geolsoc.org.uk/SUP18685 .

Structural and electrical characterizations of InxGa1-xAs/InP structures for infrared photodetector applications

Three InGaAs/InP structures for photodetector applications were grown with different indium compositions by MBE technique. The structural properties of the samples have been obtained by means of high resolution X-ray diffraction and secondary ion mass spectrometry measurements. Three InGaAs/InP metal-semiconductor-metal devices were fabricated at room temperature. The experimental forward and reverse bias current–voltage characteristics of the devices such as ideality factor, barrier height, and saturation current were evaluated considering the structural properties of the grown structures. The carrier recombination lifetime and diffusion length in the devices were also calculated using carrier density and mobility data obtained with Hall effect measurement at room temperature. It was determined that all room temperature fabricated devices improved the Schottky barrier height. Especially, the device fabricated on the lower mismatched structure exhibited barrier height enhancement from 0.2 eV, which is the conventional barrier height to 0.642 eV. In addition, the obtained results show that the room temperature fabricated devices on InGaAs/InP structures can be convenient for infrared photodetector applications.

Stable isotope imaging of biological samples with high resolution secondary ion mass spectrometry and complementary techniques

Stable isotopes are ideal labels for studying biological processes because they have little or no effect on the biochemical properties of target molecules. The NanoSIMS is a tool that can image the distribution of stable isotope labels with up to 50nm spatial resolution and with good quantitation. This combination of features has enabled several groups to undertake significant experiments on biological problems in the last decade. Combining the NanoSIMS with other imaging techniques also enables us to obtain not only chemical information but also the structural information needed to understand biological processes. This article describes the methodologies that we have developed to correlate atomic force microscopy and backscattered electron imaging with NanoSIMS experiments to illustrate the imaging of stable isotopes at molecular, cellular, and tissue scales. Our studies make it possible to address 3 biological problems: (1) the interaction of antimicrobial peptides with membranes; (2) glutamine metabolism in cancer cells; and (3) lipoprotein interactions in different tissues.

Stable isotope cellular imaging reveals that both live and degenerating fungal pelotons transfer carbon and nitrogen to orchid protocorms

The objective of this study was to elucidate the transfer of nutrient elements in orchid symbiotic protocorms at the cellular level by imaging of stable isotope tracers. We address the long-standing question of whether nutrients move by transport across the symbiotic interface or solely by lysis of fungal pelotons. [U-(13) C]glucose and (15) NH4 (15) NO3 were added to Ceratobasidium sp. hyphae extending from symbiotic protocorms of Spiranthes sinensis. Isotope images were taken from resin-embedded sections of protocorms using ultra-high spatial resolution secondary ion mass spectrometry (SIMS). Analyses of regions of interest were conducted on isotope ratio images for fungal and host structures. Amyloplasts adjacent to young pelotons showed elevated (13) C/(12) C, which indicated that fungal carbon (C) was transferred from live hyphae. Senescent pelotons and their surrounding host cytoplasm showed significantly higher isotope ratios than young pelotons and surrounding host cytoplasm. These results indicate an inflow of C to senescent hyphae, which was then transferred to the host. The findings of this study provide some support for each of the two contradictory hypotheses concerning nutrient exchange in the symbiotic protocorm: the interface between the symbionts is involved before fungal senescence, and peloton degradation also releases a significant amount of C and nitrogen to host cells.

Localization of iron in rice grain using synchrotron X-ray fluorescence microscopy and high resolution secondary ion mass spectrometry

Cereal crops accumulate low levels of iron (Fe) of which only a small fraction (5–10%) is bioavailable in human diets. Extensive co-localization of Fe in outer grain tissues with phytic acid, a strong chelator of metal ions, results in the formation of insoluble complexes that cannot be digested by humans. Here we describe the use of synchrotron X-ray fluorescence microscopy (XFM) and high resolution secondary ion mass spectrometry (NanoSIMS) to map the distribution of Fe, zinc (Zn), phosphorus (P) and other elements in the aleurone and subaleurone layers of mature grain from wild-type and an Fe-enriched line of rice (Oryza sativa L.). The results obtained from both XFM and NanoSIMS indicated that most Fe was co-localized with P (indicative of phytic acid) in the aleurone layer but that a small amount of Fe, often present as “hotspots”, extended further into the subaleurone and outer endosperm in a pattern that was not co-localized with P. We hypothesize that Fe in subaleurone and outer endosperm layers of rice grain could be bound to low molecular weight chelators such as nicotianamine and/or deoxymugineic acid.

二次元高分解能二次イオン質量分析装置（NanoSIMS）を用いた生物試料の元素イメージング

二次元高分解能二次イオン質量分析装置（NanoSIMS）を用いた生物試料の元素イメージング

An investigation of the oxidation behaviour of zirconium alloys using isotopic tracers and high resolution SIMS

High resolution secondary ion mass spectrometry (SIMS) analysis has been used to study the oxidation mechanisms when commercial low tin ZIRLO™1Low tin ZIRLO™ is a trademark of Westinghouse Electric Company LLC in the United States and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.1 and Zircaloy 4 materials are exposed to corroding environments containing both 18O and 2H isotopes. Clear evidence has been shown for different characteristic distributions of 18O before and after the kinetic transitions, and this behaviour has been correlated with the development of porosity in the oxide which allows the corroding medium to penetrate locally to the metal/oxide interface.

Atomic diffusion of gradient ultrafine structured surface layer produced by T10 steel rubbing against 20CrMnTi steel

Microstructure evolution and elements distribution in the dry sliding friction induced highly deformed layer of T10 steel pin sliding against 20CrMnTi disk was studied by means of Optical Microscopy (OM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray Diffractometry (XRD) and Secondary Ion Mass Spectrometry (SIMS). The gradient ultrafine ferrites were produced in the highly deformed layer of T10 steel pin specimen along the longitudinal section with the increasing depth, whose grain sizes were in the range from 10nm to 200nm. The diffusion behavior of Cr and Ti in such a highly deformed layer was investigated.

A multimodal mass spectrometry imaging approach for the study of musculoskeletal tissues

Imaging mass spectrometry combines the chemical sensitivity and specificity of mass spectrometry with microscopic imaging resolution. The ability to simultaneously obtain images from detected analytes allows us to know the composition of the surface of a thin tissue section. Although the technology is very well known and different applications have been used like in the classification of different diseases, little has been done in musculoskeletal tissues. Rheumatoid Arthritis (RA) is a widespread musculoskeletal disease that exhibits an extensive molecular complexity that is poorly understood. In this paper a multimodal mass spectrometry imaging (MSI) strategy was applied to identify and localize biomolecules such as lipids, peptides and proteins in bone, muscle or skin from the limb of a mouse model of RA. High spatial resolution Secondary Ion Mass Spectrometry (SIMS) imaging was used to image the elemental and small molecular distributions. Matrix Assisted Laser Desorption/Ionization (MALDI) imaging complemented these studies revealing a specific distribution of phospholipids and peptides/proteins. A protocol that employs “on tissue digestion/off tissue analysis” was established for orthogonal peptide/protein identification. Among the identified proteins were cytokines (like interleukin-18), cytoskeleton related proteins (actin, tubulin or myosin) or proteins of the family of metalloproteinases that are involved in inflammation triggering and autoimmune responses in RA. The results of this multimodal MSI and complementary proteomics approach resulted in a multitude of protein localizations and local interactions that reveal detailed molecular signatures from the different regions that constitute the musculoskeletal tissues affected by RA. The information provided by multimodal SIMS imaging and MALDI-MSI, reveals new and future possibilities for the study of musculoskeletal diseases.

Overcoming Low Ge Ionization and Erosion Rate Variation for Quantitative Ultralow Energy Secondary Ion Mass Spectrometry Depth Profiles of Si1–xGex/Ge Quantum Well Structures

We specify the O(2)(+) probe conditions and subsequent data analysis required to obtain high depth resolution secondary ion mass spectrometry profiles from multiple Ge/Si(1-x)Ge(x) quantum well structures (0.6 ≤ x ≤ 1). Using an O(2)(+) beam at normal incidence and with energies >500 eV, we show that the measured Ge signal is not monotonic with concentration, the net result being an unrepresentative and unquantifiable depth profile. This behavior is attributed to a reduced Ge ionization rate as x approaches 1. At lower beam energies the signal behaves monotonically with Ge fraction, indicating that the Ge atoms are now ionizing more readily for the whole range of x, enabling quantitative profiles to be obtained. To establish the depth scale a point-by-point approach based on previously determined erosion rates as a function of x is shown to produce quantum well thicknesses in excellent agreement with those obtained using transmission electron microscopy. The findings presented here demonstrate that to obtain reliable quantitative depth profiles from Ge containing samples requires O(2)(+) ions below 500 eV and correct account to be taken of the erosion rate variation that exists between layers of different matrix composition.

Quantification of grain boundary equilibrium segregation by NanoSIMS analysis of bulk samples

A technique for the quantification of equilibrium grain boundary segregation by high resolution secondary ion mass spectroscopy (NanoSIMS) on simple metallographically polished surfaces has been demonstrated for the model system of sulphur segregation to nickel grain boundaries. Samples of nickel containing 5.4 wt ppm of sulphur were annealed at different temperatures to achieve different equilibrium sulphur grain boundary concentrations, ranging from less than 1% to about 50% of a monolayer. Quantification was carried out from sulphur concentration profiles acquired across about 20 grain boundaries in each sample. An internal standard (nickel containing a known concentration of sulphur in solid solution) was used for calibration. It is found that, depending on the annealing temperature, the average grain boundary sulphur concentration ranges from 0.9 to 25.8 ng cm–2 (or 1.7 1013 to 4.8 1014 atoms cm–2), i.e. ~0.015 to ~0.43 monolayer. Thermodynamic analysis gives a segregation free energy of −97.8 kJ mol–1 and a grain boundary sulphur concentration at saturation of 26.7 ng cm–2 (or 5.0×1014 atoms cm–2), i.e. ~0.44 monolayer, in good agreement with previous measurements on this system. The limit of detection of the technique is shown to be as low as 0.24 ng cm–2 (or 4.5×1012 atoms cm–2), i.e. ~0.004 monolayer, with a counting time of only 10 min. Copyright © 2012 John Wiley &amp; Sons, Ltd.

SIMS imaging of the nanoworld: applications in science and technology

Secondary Ion Mass Spectrometry (SIMS) enables surface chemical analysis of nano-scaled objects and chemical imaging of nano-scaled details of natural or artificial objects. This review presents the state of the art in nanoscale SIMS analysis. At first a short introduction into recent instrumentation for high resolution SIMS imaging and the limiting factors of lateral resolution is given. The next section covers the chemical analysis of nanoparticles. Recent applications of nanoscale imaging SIMS in geology, cosmochemistry, materials research, cellular biology, ecology and medical research are summarized and illustrated by examples.