Growth mechanisms of oxides formed on Fe–9Cr steel in high pressure carbon dioxide studied using imaging SIMS

The recent article of Collingwood and Dobson [1] is an important article that emphasizes the importance of the characterization and mapping of iron compounds in the iron-rich brain regions with the aim contributing to our understanding of the role of pathological accumulations of iron in the regions of the brain affected by neurodegenerative disease. Nonetheless, below, I discuss ion and electron microprobe techniques for detecting and quantifying iron, not specifically cited by the authors, that allow the mapping of total iron (SIMS and XEDS) at the cellular and sub cellular level and the characterization and mapping of iron compounds (EELS) at ultra structural level. SIMS (Secondary Ion Mass Spectroscopy) imaging technique, allows direct identification of chemical elements with high sensitivity and specificity and, as a consequence, elemental distribution can be visualized (chemical mapping) by SIMS imaging. The physical basis of the method is the following: under the bombardment of the samples by primary ions, the monoatomic or polyatomic species that composed the analyzing object are sputtered. One part of these emitted species is ionized and the SIMS instrument, with the help of a mass spectrometer, sort and maps the ejected ions by their m/e ratio. The latest generation of SIMS instruments, the NanoSIMS-50 instrument, operating in scanning mode, is equipped with a parallel detection system that allows the simultaneous acquisition of five elements which insures a perfect colocalization between simultaneously recorded images. This instrument is particularly useful to identify elements at a sub cellular level, because it is possible to attain resolutions of 50–100 nm with the Cs source and 150–200 nm with the O− source [2]. NanoSIMS microscopy has been already used with success for the visualization of the morphological and chemical alterations taking place in well-characterized regions in pathological brain, in particular in the study of iron distribution in Alzheimer disease tissue [3,4]. Multielemental analysis (nitrogen, phosphorus, sulphur and iron) were performed on semi-thin or ultra-thin sections of Transmission Electron Microscopy (TEM) preparations brain tissue. The possibility of using light microscopy, TEM, and SIMS on the same semi-thin and ultra-thin sections allows correlation between structural and analytical observations at sub-cellular and ultrastructural level. It has been shown that the iron-rich region mapped by nanoSIMS in the hippocampus of AD patients are ferritin and/or hemosiderin rich regions. XEDS (X-Ray Energy dispersive Spectroscopy) and EELS (Electron Energy Loss Spectroscopy) are electron probe nanoanalysis techniques that, associated with transmission electron microscopes (ConventionalTEM, ScanningTEM or ConventionalTEM working in scanning mode, so-called AnalyticalTEM, ATEM), provide compositional maps of ultra-thin sections with nanometric resolution (1–10 nm): XEDS by detecting the element specific X-ray emission under excitation of incident electrons: EELS by detecting element specific energy loss of incident electrons. EELS provides theoretically higher detection sensitivity than EDS due to the larger number of primary events collected in the

Interpretation of time-of-flight secondary ion mass spectroscopy (TOF-SIMS) images from rough samples such as particles, fibers, or biological specimens can be problematic because the images are influenced not only by the sample chemistry but also by topographical features. In this article we have investigated the influence of spherical and cylindrical features on total ion yields, relative ion yields, and feature shape. TOF-SIMS images of Pluronic coated fibers and polystyrene spheres were collected using both triple focusing time and reflectron geometry instruments and a 25keV Ga+ primary ion source. The fibers and spheres were analyzed on both conducting and insulating substrates to assess the importance of field effects. Trends in the images have been explored using principal components analysis and Poisson and multinomial mixture models. The T2 test was employed to assess the statistical significance of results. The results identify three important topographic effects. The size and shape of features can be distorted as a result of the incidence angle of the primary ion beam. Additionally, both the absolute and relative intensities of ion peaks vary as a result of topography. In regions where the primary ion beam impacted the sample at a glancing angle, the relative intensity of molecular fragments characteristic of the Pluronic surfactant was up to three times higher than in regions where the beam impacted the sample at a normal angle. Comparison of results from conducting and insulating samples suggests that changes in the relative ion yields resulted primarily from differences in the incidence angle of the primary ion beam while changes in the total ion yield are influenced by both the incidence angle and distortion of the electric field by the particle. This study documents that topographic features can influence not only the absolute intensity of ion peaks but can also alter peak ratios in a statistically significant manner. In this light, a greater degree of caution is recommended when interpreting TOF-SIMS images from topographically complex samples.

New PhytologistVolume 182, Issue 1 p. 284-284 Free Access Corrigendum This article corrects the following: The apoplast and its significance for plant mineral nutrition Burkhard Sattelmacher, Volume 149Issue 2New Phytologist pages: 167-192 First Published online: July 7, 2008 First published: 06 March 2009 https://doi.org/10.1111/j.1469-8137.2009.02741.xAboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL New Phytologist 149 (2001), 167–192 Since the publication of Sattelmacher (2001), it has been brought to our attention that the secondary ion mass spectroscopy (SIMS) images in Fig. 3 have been wrongly attributed. The images are courtesy of W. H. Schroeder, U. Breuer, R. Stelzer and M. Gierth. The correct Fig. 3 is printed below. Fig. 3 Secondary ion mass spectroscopy (SIMS) images showing the distribution of 39K+ and 85Rb+ in a freeze-dried cryosection of a barley root. A droplet of a 60-mol m−3 RbCl solution was added to the basis of a nodal root of an intact transpiring plant 120 s prior to freezing the plant with liquid propane. (a) SIMS mapping of 39K+ on a root cross section, imaging the cell contents of the cortex and the stele. Note that 39K+ is absent from the surface adhering test solution, the cell walls and the xylem vessels in the stele. (b) The applied 85Rb+ from the test solution exceptionally appears on the root surface but neither in the apoplast nor in the symlast of the root cortex and the stele, respectively. (c) Summarized SIMS images of both 39K+ plus 85Rb+ to show the total extent of the analysed cryosection. (d) Summarized SIMS images as in (c): The isotope distribution map of 39K+ was framed by a green line and of 85Rb+ by a light blue line. Courtesy of W. H. Schroeder, U. Breuer, R. Stelzer and M. Gierth. We apologize to our readers for this mistake. Reference Sattelmacher B. 2001. The apoplast and its significance for plant mineral nutrition. New Phytologist 149: 167– 192. Volume182, Issue1April 2009Pages 284-284 ReferencesRelatedInformation

Secondary ion mass spectroscopy (SIMS) is a powerful method for element distribution examination of conducting and semi-conducting surfaces at high spatial resolution and with a high sensitivity. Routine surface analysis produces about 8 to 15 images in a short time, each of which displays the intensity distribution of one mass, thus generating a multispectral SIMS image. Formation of occlusions, segregations, and the overall location of the elements relative to each other, are difficult to recognise when looking at n separate 2-D images. Image fusion is a process whereby images obtained from various sensors, or at different moments of time, or under different conditions, are combined together to provide a more complete picture of the object under investigation. The process of combining SIMS images may be viewed as an attempt to compensate for the inherent effect of SIMS to channel the information obtained from the sample into different images, corresponding to different element phases. The wavelet transform is a powerful method for fusion of images. This work covers the use of wavelet based fusion algorithms on multispectral SIMS images, evaluating the performance of different wavelet based fusion rules on different type of image systems and comparing the results to conventional fusion techniques. An aim of this study is to increase the information, i.e. the number of masses, which can be merged into one image in order to enhance the perception and interpretation of the SIMS surface images.

Plasma lithography, combining plasma deposition with photolithography, is described as a versatile method to manufacture all-polymeric substrates with thin-film patterns for applications in biomedical engineering. Patterns of a hydrophobic fluorocarbon plasma polymer with feature sizes between 5 and 100 μm were deposited on a base substrate in a lift-off process; an intermediate tetraglyme plasma polymer layer provides non-fouling properties to the base substrate. Careful analysis of critical process parameters identified the narrow window of process conditions that led to the formation of functional surface patterns. High pattern fidelity, aspect ratios, and resolution of the patterns are demonstrated by atomic force microscopy. Electron spectroscopy for chemical analysis (ESCA) and secondary ion mass spectroscopy (SIMS) were used to characterize the surfaces, showing good retention of the original chemical structure of the pattern components throughout the process. SIMS imaging was used for specific chemical imaging of the components. Potential applications for the patterned polymer films, e.g., for studying cell behavior in vitro in dependence of shape and size of adhering cells, are discussed.

Microbiological and Chemical Analyses of Stainless Steel and Ceramics Subjected to Repeated Soiling and Cleaning Treatments

As liquid phase epitaxial (LPE) growth and array fabrication processes have matured to give excellent wafer average performance, the yield limiter for infrared focal plane arrays (IRFPAs), especially large ones, have become outages. In this work, significant progress has been made in identifying the source and eliminating outages from LPE grown Hg1−xCdxTe P-on-n structures. Historically, studies of the sources of outages have employed defect etches to look for dislocations and other crystalline defects, and secondary ion mass spectroscopy (SIMS), imaging SIMS, and sputter initiated resonance ion spectrometry (SIRIS) to look for impurities at critical interfaces. Using these techniques, trends were established, but direct correlation with outages have been observed. In LPE grown materials, where the dislocation densities are always below 5×105 cm−2, and often below 1×105 cm−2 on CdZnTe substrates, dislocations only account for a few outages. In order to understand the source(s) of outages, a failure analysis was performed on several long wavelength IRFPAs. Using a dilute etchant, the metals and then cap layers of some 64×64 pixel IRFPAs which had excellent average performance, but suffered from a high density of pixels with excessive leakage current, were removed. Using a scanning electron microscope with energy dispersive spectroscopy capability, the presence of carbon particles was correlated with excessive leakage current on a 1:1 pixel basis. A series of experiments was then conducted which isolated the source of the particles to the cap layer growth process, which was consequently changed to eliminate them. The process improvements have reduced the particle density to below the measurement limit of the optical measurement technique implemented to monitor the density of particles on witness wafers. These improvements are resulting in IRFPAs with significantly improved operability.

The morphology of bulk-heterojunctions (BHJ) is critically important for conjugated polymer and fullerene blend solar cells. To alter the morphology, high pressure (gas phase) carbon dioxide (CO(2)) treatment is applied to poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) blend films under ambient temperature. This process can achieve vertically phase separated morphology such that PCBM distributes toward the film surface, which is suggested by secondary ion mass spectroscopy (SIMS), contact angle, X-ray photoelectron spectroscopy (XPS) and cross-sectional scanning electron microscope (SEM) studies. While pristine P3HT films do not show a significant change upon CO(2) treatment, pristine PCBM films are plasticized in high pressure CO(2). Thus, PCBM is selectively plasticized by CO(2) in the blend film and is drawn towards the surface due to depressed surface energy, although P3HT tends to distribute around the surface without CO(2). This stratification process can enhance solar cell performance. 55% improvement is achieved in the power conversion efficiency of the CO(2) treated device compared to the untreated one, indicating that CO(2) treatment can be a good candidate for optimizing the morphology and enhancing the performance of BHJ polymer solar cells.

The ability to control the shape and size of cells is an important enabling technique for investigating influences of geometrical variables on cell physiology. Herein we present a micropatterning technique ("plasma lithography") that uses photolithography and plasma thin-film polymerization for the fabrication of cell culture substrates with a cell-adhesive pattern on a cell-repellent (non-fouling) background. The micron-level pattern was designed to isolate individual vascular smooth muscle cells (SMC) on areas with a projected area of between 25 and 3600 microm(2) in order to later study their response to cytokine stimulation in dependence of the cell size and shape as an indication for the phenotypic state of the cells. Polyethylene terephthalate substrates were first coated with a non-fouling plasma polymer of tetraglyme (tetraethylene glycol dimethyl ether). In an organic lift-off process, we then fashioned square- and rectangular-shaped islands of a thin fluorocarbon plasma polymer film of approximately 12-nm thickness. Electron spectroscopy for chemical analysis and secondary ion mass spectroscopy were used to optimize the deposition conditions and characterize the resulting polymers. Secondary ion mass spectroscopy imaging was used to visualize the spatial distribution of the polymer components of the micropatterned surfaces. Rat vascular SMC were seeded onto the patterned substrates in serum-free medium to show that the substrates display the desired properties, and that cell shape can indeed be controlled. For long-term maintenance of these cells, the medium was augmented with 10% calf serum after 24 h in culture, and the medium was exchanged every 3 days. After 2 weeks, the cells were still confined to the areas of the adhesive pattern, and when one or more cells spanned more than one island, they did not attach to the intervening tetraethylene glycol dimethyl ether (tetraglyme) background. Spreading-restricted cells formed a well-ordered actin skeleton, which was most dense along the perimeter of the cells. The shape of the nucleus was also influenced by the pattern geometry. These properties make the patterned substrates suitable for investigating if the phenotypic reversion of SMC can be influenced by controlling the shape and size of SMC in vitro.

Several modern microanalytical techniques strive to describe the chemical composition of materials by images at ever increasing spatial resolution and sensitivity. Digital micrographs that depict the two‐dimensional distribution of selected constituents (analytical maps) across small areas of a sample are one of the most effective vehicles for recording the retrieved information quantitatively. One technique in particular, secondary ion mass spectroscopy or, more appropriately, spectrometry (SIMS) imaging, has been advanced during the last two decades to reach analytical image resolution of a few tens of nanometers. High‐resolution SIMS imaging has become practical due to the development of finely focused scanning ion probes of high brightness, incorporated in scanning ion microscopes or microprobes (SIM), as is illustrated in this context. SIMS images are shown that embody a wealth of correlative interwoven information in a most compact form. These can be thought of as two‐dimensional projections of an abstract multidimensional space that encompasses the spatial dimensions (physical structure), the mass or atomic number dimension (chemical structure), and, as a further variable, the concentration of each constituent in a sample (quantification). In this article, the fundamental principles that underlie the formation of SIMS images, the requirements and limitations in attaining high spatial resolution (<100 nm), the engineering details of a state‐of‐the‐art SIM, and a number of applications, illustrated by images, in the materials sciences are reviewed.

7075-T6 aluminium alloys panels were surface conditioned in a titanium colloid suspension, under a variety of different conditions, and subsequently these samples were immersed in a ZnO + H3PO4 coating mixture, and the phosphate coating layers characterized. Morphologies observed by scanning electron microscopy (SEM) reveal that the coating layer consists of two phases, namely an amorphous phase, which is directly bonded to the substrate, and a crystalline phase, in which larger crystal grains grow on top of the amorphous base. Chemical compositions of the coating layers were analysed by X-ray photoelectron spectroscopy (XPS) and by static and imaging secondary ion mass spectroscopy (SIMS). It is found that the details of the surface conditioning affect the final coating, both in terms of morphology and chemical composition. For example, larger amounts of Zn and P are detected in coatings for which the initial conditioning is done at 40°C, compared with room temperature; a similar statement can be made for surfaces which are water rinsed after the Ti pretreatment, compared with those which are not water rinsed prior to the coating treatment.

The SiO2/TiN interface is prone to sub-critical decohesion by crack extension along the interface when exposed to moisture. As with conventional sub-critical crack growth in bulk silica, the rate of decohesion is dependent on both the relative humidity and the strain energy release rate. One of the unusual observations we have noted is that the decohesion velocity of narrow strips is highly sensitive to the exposure time in the humid environment, suggesting that the moisture diffuses into the interface ahead of the propagating decohesion crack, causing a form of hydrolytic weakening of the interface. In seeking to establish the origin of this behavior, we report measurements of moisture diffusion along the SiO2/TiN interface using Imaging Secondary Ion Mass Spectroscopy (SIMS) after immersion in water containing radioactive tracers, 2D and 18O. Analysis of images formed using 2D and 18O revealed that both diffuse along the interface with a diffusivity of (6 ±2)×10−13 cm2/sec, a value about 104 times faster than the bulk diffusion in the SiO2 dielectric.

AbstractChromium specimens were annealed in hydrogen to reduce the level of sulphur impurity and thus improve the oxide adhesion. The growth mechanism of the chromia scale in 0·1 atm oxygen at 950°C was investigated by oxidising sequentially in natural oxygen and then in gas enriched in 18O; the distribution of 18O in the scale was determined using imaging secondary ion mass spectroscopy (SIMS). From preliminary results it was found that substantial oxygen diffusion occurred. This differs from the growth mechanism of chromia on vacuum annealed material which, as far as solid state transport is concerned, mainly involves cation transport. The theory that sulphur promotes cation diffusion via grain boundaries in chromia and that removal of the sulphur favours oxygen diffusion is supported by the results. From examination of the distribution of the oxygen isotopes at the scale/gas interface, it is shown that their distribution is not uniform, from which it can be inferred that the growth of oxide at that interface was not uniform during oxidation in the 18O-rich gas.MST/967

Numerical simulations of high pressure carbon dioxide fluid fluidized beds

The Hydrogen Induced Cracking (HIC) and Sulfide Stress Cracking (SSC) behaviours of sour service and non-sour service carbon steel API 5L X65 were investigated under high pressure carbon dioxide environments, containing elevated amount of hydrogen sulphide (H2S); the test environments simulated offshore pipelines transporting full-well streams in high carbon dioxide (CO2) environments with elevated H2S concentrations. It was systematically studied under standard NACE condition and high pressure carbon dioxide field condition with variation in other key parameters (temperature, pressure and hydrogen sulfide concentration). The HIC and SSC were tested using a High Pressure and High Temperature (HPHT) Autoclave. The surface cracking morphology was analysed using Scanning Electron Microscopy (SEM), Ultrasonic Technique (UT) and Magnetic Particle (MP). The results showed that no cracks were detected in NACE standard and field-condition SSC tests for both sour service and non-sour services carbon steel. In HIC test, crack was detected on non-sour service carbon steel in NACE standard test while no crack was detected on field condition-based tests for both types of carbon steel.