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Large tilt angle (LTA) implantation has been employed in Si manufacturing processes in many applications, such as lightly doped drain and halo implant. The depth profile of boron ions usually consists of only single peak at incident angle of 0° with respect to the perpendicular of the silicon surface. However, an abnormal dual-peak profile was observed at LTA (>40°) with incident energy of 160 keV. By using a Monte Carlo method to simulate the ion implant process, it was found that the projected range of boron ions agrees completely with the formation of the first peak position that is shallower in depth, while the cause for the second peak that corresponds with a depth much deeper in the Si substrate was unknown. During the simulation, it was also found that when the tilt angle was increased, the sputtering yields and Si displacements increased significantly, and this phenomenon indicates that during LTA implantation, Si damage may not be negligible anymore. The Si damage effect that was as due to either low Si density or transient Si displacement in the simulation could have led to partial incident boron ions penetrating much deeper into the Si substrate and thus, caused the emergence of the second peak. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The utility of energy sequencing for extracting an accurate matrix level interface profile using ultra-low energy SIMS (uleSIMS) is reported. Normally incident O over an energy range of 0.25-2.5 keV were used to probe the interface between SiGe/Si, which was also studied using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). All the SIMS profiles were linearized by taking the well understood matrix effects on ion yield and erosion rate into account. A method based on simultaneous fitting of the SIMS profiles measured at different energies is presented, which allows the intrinsic sample profile to be determined to sub-nanometer precision. Excellent agreement was found between the directly imaged HAADF-STEM interface and that derived from SIMS. [ABSTRACT FROM AUTHOR]

Understanding the interplay of climatic and biological events in deep time requires resolving the precise timing and pattern of paleotemperature changes and their temporal relationship with carbon cycle variations and biodiversity fluctuations. In situ oxygen isotope analyses of conodont apatite from South China enables us to reconstruct high-resolution seawater temperature records across the Permian–Triassic boundary (PTB) intervals in the upper slope (Meishan), lower slope (Shangsi), and carbonate platform (Daijiagou and Liangfengya) settings. Constrained by the latest high-precision geochronological dates and high-resolution conodont biozones, we can establish the temporal and spatial patterns of seawater temperature changes and assess their potential connections with the carbon cycle disruption and biodiversity decline. We find a rapid warming of ~ 10 °C during the latest Permian–earliest Triassic that postdated the onset of the negative shift in δ 13 C carb by ~ 81 kyr (thousand years), the abrupt decline in δ 13 C carb by ~ 32 kyr and the onset of mass extinction by ~ 23 kyr, which contradicts previous claims that the extreme temperature rise started immediately before or coincided with the onset of mass extinction. Our new evidence indicates that climate warming was most likely not a direct cause for the main pulse of the end-Permian mass extinction (EPME), but rather a later participant or a catalyst that increased the pace of the biodiversity decline. In addition, a prominent cooling is recorded in the earliest Changhsingian, with the main phase (a drop of ~ 8 °C in ~ 0.2 Ma) confined to the lower part of the Clarkina wangi zone and synchronous with the positive limb of the carbon isotope excursion (CIE) around the Wuchiapingian–Changhsingian boundary (WCB) in Meishan and Shangsi. Further long-term and high-resolution studies from other sections are needed to confirm the full contexts and underlying dynamics of the WCB “cooling event”. [ABSTRACT FROM AUTHOR]

To determine the magnitude of N-isotope fractionation between diamond and its parental fluid, detailed C- and N-isotope analyses of a complexly-zoned, eclogitic diamond (JDE-25) were undertaken using secondary ion mass spectrometry. Combined C- and N-isotope and N-abundance measurements were made across four distinct growth zones and show the following range of values: δ 13 C = − 5.7 to − 2.1‰; δ 15 N = − 7.0 to + 5.5‰; [N] = 104 to 5420 at. ppm. The core zone displays a continuous, rimward increase in δ 13 C and δ 15 N values and decreases in N-abundance, and is interpreted to have formed by fractional crystallization of diamond from a single pulse of fluid (i.e., closed system). Modelling of the isotopic and abundance data from the core zone yields a diamond–fluid nitrogen partition coefficient ( K N ) of 4.4 and a N-isotope fractionation factor (∆ 15 N diam–fluid ) of − 4.0 ± 1.2‰ (2σ) at ~ 1100 °C, for precipitation from a pure carbonate fluid. Calculated K N and ∆ 15 N diam–fluid values would have larger magnitudes if JDE-25 formed from a more complex fluid, in which the carbonate species formed only a minor component. Theoretical calculations of N-isotope fractionation between the principal N-species associated with upper mantle fluids (N 2 , NH 3 or NH 4 + ) and the CN − molecule, as an analogue for the carbon–nitrogen bond in diamond, yield the following ∆ 15 N diam (CN)–fluid estimates at 1100 °C: − 3.6‰ for NH 4 + , − 2.1‰ for N 2 and − 1.4‰ for NH 3 . The theoretical calculations provide only minimum estimates of the true diamond–fluid N-isotope fractionation factor, given that the C–N single bond in diamond would have a lower affinity for 15 N than the stronger C–N triple bond in the CN − molecule. Accordingly, the theoretical N-isotope fractionation factors are consistent with the empirical fractionation factor derived from diamond JDE-25. As a consequence of the large magnitude of ∆ 15 N diam–fluid , intracrystalline N-isotope variations in diamond should provide a sensitive test for fluid-related, fractional crystallization processes. Furthermore, the large magnitude of ∆ 15 N diam–fluid could be reflected in the wide range of δ 15 N values for natural diamonds and the absence of clearly defined modes for the N-isotope compositions of peridotitic and eclogitic diamonds. [ABSTRACT FROM AUTHOR]

We present a new strategy for analyzing imaging time-of-flight SIMS data sets affected by detector saturation. Rather than attempt to correct the measured data to remove saturation, we incorporate the detector behavior into the statistical basis of the analysis. This is performed within the framework of maximum a posteriori reconstruction. The proposed approach has several advantages over previous techniques. No approximations are involved other than the assumed model of the detector. The method performs well even when applied to highly saturated and/or single-scan data sets. It is statistically rigorous, correctly treating the underlying statistical distribution of the data. It is also compatible with Bayesian methods for incorporating prior knowledge about sample properties. An efficient iterative scheme for solving the proposed equations is presented for the case of the bilinear model commonly used in analyses of SIMS data. The correctness of the approach and its efficacy are demonstrated on synthetic data sets. The method is found to perform better than a widely-used data-correction method used in combination with alternating-least-squares Multivariate Curve Resolution analysis. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We report technical and data treatment methods for making accurate, high-precision measurements of 18 O/16 O in Ca- Mg- Fe garnet utilising the Cameca IMS 1280 multi-collector ion microprobe. Matrix effects were similar to those shown by previous work, whereby Ca abundance is correlated with instrumental mass fractionation ( IMF). After correction for this effect, there appeared to be no significant secondary effect associated with Mg/ Fe2+ for routine operational conditions. In contrast, investigation of the IMF associated with Mn- or Cr-rich garnet showed that these substitutions are significant and require a more complex calibration scheme. The Ca-related calibration applied to low- Cr, low- Mn garnet was reproducible across different sample mounts and under a range of instrument settings and therefore should be applicable to similar instruments of this type. The repeatability of the measurements was often better than ± 0.2‰ (2 s), a precision that is similar to the repeatability of bulk techniques. At this precision, the uncertainties due to spot-to-spot repeatability were at the same magnitude as those associated with matrix corrections (± 0.1-0.3‰) and the uncertainties in reference materials (± 0.1-0.2‰). Therefore, it is necessary to accurately estimate and propagate uncertainties associated with these parameters - in some cases, uncertainties in reference materials or matrix corrections dominate the uncertainty budget. [ABSTRACT FROM AUTHOR]

Abstract: The geological evolution in the southwestern Chinese Tianshan orogen in NW China is poorly understood because of controversial geochronological results of the low-temperature eclogites. It is likely due to Sm–Nd and Rb–Sr isotopic disequilibrium in different mineral fractions, excess 40Ar in the high-pressure K-bearing minerals, and multi-stage growths of zircon in U–Pb system. Rutile, as a typical eclogite-facies mineral with high U/Pb ratio, is a feasible candidate to constrain the eclogite-facies metamorphic event. In this study, we measured U–Pb rutile age data using SIMS (Cameca IMS 1280) for low-temperature eclogites from southwestern Chinese Tianshan orogen, NW China. We demonstrate that SIMS is a powerful technique for in-situ U–Pb dating of rutile with U content as low as 1ppm. SIMS U–Pb rutile dating yielded an age of 318±7Ma, which may record the time when the rocks cooled down to the closure temperature of Pb in rutile (ca. 500°C), but should be very close to the time of eclogite-facies metamorphism in terms of common fast exhumation of coesite-bearing eclogite. This new proof strongly suggests a late Carboniferous collision between Kazakhstan–Yili block and Central Tianshan microcontinent. [ABSTRACT FROM AUTHOR]

Abstract: The Proterozoic Jaduguda U (–Cu–Fe) deposit in the Singhbhum shear zone, eastern India hosts the oldest and most productive uranium mine in India. The polymetallic ores in Jaduguda are hosted in altered, sheared and metamorphosed volcano-sedimentary rocks, and this complexity has lead to a confusion in ore genetic models for the deposit. A characteristic of the mineralization is the presence of abundant tourmaline, locally exceeding 50vol.%, which is spatially associated with U and Cu mineralization in all rock types and its chemical and B-isotopic variations provide important constraints on fluid source(s) and ore deposit affinity. We examined tourmaline from the U–Cu ore zone and adjacent footwall and hanging wall meta-sedimentary rocks. Tourmaline grew in three different stages. Pre-kinematic Tourmaline-1, represented by fractured and porphyroblastic grains, is ubiquitous in the wall rocks and the U–Cu zone. Syn-kinematic Tourmaline-2 and post-kinematic Tourmaline-3 are found exclusively in the U–Cu zone, where intense shear deformation has focussed fluid flow, alteration and metamorphism. All tourmalines belong to the alkalic group and most are dravitic. Systematic contrasts in major element compositions between Tourmaline-1 and Tourmaline-2 are attributed to the influence of high fluid/rock ratios in the U–Cu ore zone. Tourmaline from the Jaduguda deposit exhibits a wide overall range of δ11B values from −6.8 to +17.2‰. Positive values of Tourmaline-1 are irrespective of host rock and ore association (U or U+Cu), and range between +2.3 to +17.2‰ (n=44). The calculated δ11B values of fluid in equilibrium with this tourmaline (for mineralization temperatures of 300–450°C) range from ~+4 to ~+20‰. The δ11B values of syn-kinematic Tourmaline-2 are much lower than Tourmaline-1, between −6.8 and +4‰ (n=7) and the corresponding fluid δ11B values are −4.8+6‰. The high values of δ11B for Tourmaline-1 and early fluid suggest a marine evaporite or basinal brine was the source of boron, and this fits with abundant mineralogical and geochemical evidence for highly-saline fluids during mineralization. We propose that the isotopically lighter fluid associated with Tourmaline-2 and related syn-kinematic mineralization/mobilization was derived from the metamorphic volcano-sedimentary rocks at high fluid/rock ratios in and around the shear zone. Post-kinematic Tourmaline-3 is compositionally and isotopically (δ11B=+4 to +11.1‰, n=5) similar to Tourmaline-1 in the same samples, suggesting it formed by local recrystallization of the early tourmaline or from a renewed influx of saline fluids similar to those which formed the pre-kinematic mineralization. Integrating the results of this tourmaline study with the geological and geochemical characteristics of the Jaduguda U–(Cu–Fe) mineralization suggests that it is best regarded as a variant of the Fe-oxide (Cu–U–REE) or IOCG class of deposits. [Copyright &y& Elsevier]

Secondary ion mass spectrometry (SIMS or ion microprobe) remains one of the most powerful tools available to the analytical geochemist. Despite the impressive progress witnessed by other competing laboratory methods over recent years, SIMS remains unsurpassed in its combination of small sampling volumes with low analytical uncertainties. Although the current SIMS analytical design has existed for over three decades, the period 2006–2007 saw significant advances in instrumentation, analytical methodology and, not least, the characterisation of new reference materials upon which all analyses depend. As of the end of 2007 the SIMS geoscience literature was reporting total sampling masses down to the 10 fg range, spatial resolution of better than 100 nm and uncertainties on major element isotope ratio determinations of better than ± 0.2‰ (1 s). This article intends to synthesise the progress made by the geo-SIMS community during this two year period and will also highlight some specific research results that were only possible due to the unique capabilities provided by SIMS. [ABSTRACT FROM AUTHOR]