abstract: Mass spectrometric analysis requires that atoms from the sample be ionized in the gas phase. Secondary ion mass spectrometry achieves this by sputtering samples with an energetic primary ion beam. Several investigations of the sputtering and ionization process have been conducted. Oxygen is commonly used in secondary ion mass spectrometry (SIMS) to increase ion yields, but also can complicate the interpretation of SIMS analyses. An 18O implant in silicon has been used to quantify the oxygen concentration at the surface of sputtered silicon in order to study the dependence on oxygen of several sputtering and depth profile phenomena. The ion yield dependence of trace elements in silicon on the surface oxygen concentration is a function of the ionization potential of the element. The ion yield is high and unaffected by oxygen for elements with low ionization potential and ranges over several orders of magnitude for elements with high ionization potential. Depth resolution in sputter profiles has been shown to be degraded by the presence of oxygen, the mechanism of this effect has been investigated using an 18O implant to quantify oxygen levels and it is shown that the process does not appear to be a consequence of surface oxide formation. Molecular ions are a source of mass interference in SIMS analysis, and multiply charged atomic ion signals might be interference-free due to the possible instability of multiply-charged molecular ions. Sputtered SiH2+, AlH2+, BeH2+, Mo22+ and Mg22+ ions have been observed and appear surprisingly stable. The formation mechanism of some of these species has been explored. / Dissertation/Thesis / Ph.D. Chemistry 2012

abstract: Boron concentrations and isotopic composition of phlogopite mica, amphibole, and selected coexisting anhydrous phases in mantle-derived xenoliths from the Kaapvaal Craton were measured by secondary ion mass spectrometry in an effort to better understand the B isotope geochemistry of the subcontinental lithospheric mantle (SCLM) and its implications for the global geochemical cycle of B in the mantle. These samples display a wide, and previously unrecognized, range in their boron contents and isotopic compositions reflecting a complex history involving melt depletion and metasomatism by subduction- and plume-derived components, as well as late stage isotopic exchange related to kimberlite emplacements. Micas from ancient lithospheric harzburgite metasomatized by slab-derived fluids suggest extensive B-depletion during subduction, resulting in low-B, isotopically light compositions whereas kimberlite-related metasomatic products and a sample from the 2 Ga Palabora carbonatite have boron isotopic compositions similar to proposed primitive mantle. The results suggest that subduction of oceanic lithosphere plays a limited role in the B geochemistry of the convecting mantle. / Dissertation/Thesis / Masters Thesis Geological Sciences 2014

Parcels of diamond crystals from the A154 South kimberlite diatreme, Northwest Territories (n=281), and the Lynx kimberlite dyke, Quebec (n=6598) were examined in terms of colour, size, morphology, and UV fluorescence (A154 South samples only). A subset of stones from each parcel (A154 South: n=60, Lynx: n=20) were cut and polished to expose internal zonation and mineral inclusions. Exposed primary mineral inclusions were quantitatively analyzed for major elements by EMPA. Diamond crystals from the Kelsey Lake kimberlite diatreme, Colorado (n=20), were cut into plates and analyzed for nitrogen aggregation states by FTIR. Twelve of these stones were then analyzed with further subsets from A154 South (n=18) and Lynx (n=16) for carbon isotope ratios and nitrogen abundances by SIMS. Every diamond crystal cut and polished had its internal zonation imaged with CL. Mineral inclusion data from A154 South and Lynx show that the mantle keel of the Slave craton is slightly less depleted than that of the Superior craton, and both are less depleted than those of the Kaapvaal and Siberian cratons. Equilibration conditions plot on hotter geothermal gradients (surface heat flows ~42 mW/m2) than for those of typical Archean cratons (≤40 mW/m2). Equilibration temperatures (~1150-1250°C) are ~100-200°C hotter than previously reported from Kelsey Lake (~1020°C). Kelsey Lake and A154 South samples have carbon isotope ratios and nitrogen contents typical of most diamond populations worldwide. Diamond crystals from Lynx are entirely different, consisting of mostly Type II diamond with δ13C (vs. PDB) values from approximately -3.6 ‰ to +1.7 ‰. These 13C-enriched samples are suggested to be the result of extreme Rayleigh fractionation of diamond from a carbonate fluid and possibly input of carbon sourced from subducted abiotic oceanic crust. Also notable is that growth trends (δ13C-[NT]) for most of the samples studied show little or no consistency with published fractionation models.

Parcels of diamond crystals from the A154 South kimberlite diatreme, Northwest Territories (n=281), and the Lynx kimberlite dyke, Quebec (n=6598) were examined in terms of colour, size, morphology, and UV fluorescence (A154 South samples only). A subset of stones from each parcel (A154 South: n=60, Lynx: n=20) were cut and polished to expose internal zonation and mineral inclusions. Exposed primary mineral inclusions were quantitatively analyzed for major elements by EMPA. Diamond crystals from the Kelsey Lake kimberlite diatreme, Colorado (n=20), were cut into plates and analyzed for nitrogen aggregation states by FTIR. Twelve of these stones were then analyzed with further subsets from A154 South (n=18) and Lynx (n=16) for carbon isotope ratios and nitrogen abundances by SIMS. Every diamond crystal cut and polished had its internal zonation imaged with CL. Mineral inclusion data from A154 South and Lynx show that the mantle keel of the Slave craton is slightly less depleted than that of the Superior craton, and both are less depleted than those of the Kaapvaal and Siberian cratons. Equilibration conditions plot on hotter geothermal gradients (surface heat flows ~42 mW/m2) than for those of typical Archean cratons (≤40 mW/m2). Equilibration temperatures (~1150-1250°C) are ~100-200°C hotter than previously reported from Kelsey Lake (~1020°C). Kelsey Lake and A154 South samples have carbon isotope ratios and nitrogen contents typical of most diamond populations worldwide. Diamond crystals from Lynx are entirely different, consisting of mostly Type II diamond with δ13C (vs. PDB) values from approximately -3.6 ‰ to +1.7 ‰. These 13C-enriched samples are suggested to be the result of extreme Rayleigh fractionation of diamond from a carbonate fluid and possibly input of carbon sourced from subducted abiotic oceanic crust. Also notable is that growth trends (δ13C-[NT]) for most of the samples studied show little or no consistency with published fractionation models.

No description available.

abstract: Fluorine (F) is a volatile constituent of magmas and hydrous mantle minerals. Compared to other volatile species, F is highly soluble in silicate melts, allowing F to remain in the melt during magma differentiation and rendering F less subject to disturbance during degassing upon magma ascent. Hence, the association between fluorine in basalts and fluorine in the mantle source region is more robust than for other volatile species. The ionic radius of F- is similar to that of OH- and O2-, and F may substitute for hydroxyl and oxygen in silicate minerals and melt. Fluorine is also incorporated at trace levels within nominally anhydrous minerals (NAMs) such as olivine, clinopyroxene, and plagioclase. Investigating the geochemical behavior of F in NAMs provides a means to estimate the pre-eruptive F contents of degassed magmas and to better understand the degassing behavior of H. The partition coefficients of F were determined for clinopyroxene, olivine, plagioclase, and hornblende within melts of olivine-minette, augite-minette, basaltic andesite, and latite compositions. The samples analyzed were run products from previously-published phase-equilibria experiments. Fluorine was measured by secondary ion mass spectrometry (SIMS) using an 16O- primary beam and detection of negative secondary ions (19F-, 18O-, 28Si-). SIMS ion intensities are converted to concentrations by analyzing matrix-matched microanalytical reference materials and constructing calibration curves. For robust F calibration standards, five basaltic glasses (termed Fba glasses) were synthesized in-house using a natural tholeiite mixed with variable amounts of CaF2. The Fba glasses were characterized for F content and homogeneity, using both SIMS and electron-probe microanalysis (EPMA), and used as F standards. The partition coefficients for clinopyroxene (0.04-028) and olivine (0.01-0.16) varied with melt composition such that DF (olivine-minette) < DF (augite-minette) < DF (basaltic andesite) < DF (latite). Crystal chemical controls were found to influence the incorporation of F into clinopyroxene, but none were found that affected olivine. Fluorine partitioning was compared with that of OH within clinopyroxenes, and the alumina content of clinopyroxene was shown to be a strong influence on the incorporation of both anions. Fluorine substitution into both olivine and clinopyroxene was found to be strongly controlled by melt viscosity and degree of melt polymerization. / Dissertation/Thesis / Ph.D. Geological Sciences 2012

No description available.

The ideal properties of a structural material are light weight with extensive strength and ductility. A composite with high strength and tailorable ductility was developed consisting of nanocrystalline AA5083, boron carbide and coarser grained AA5083. The microstructure was determined through optical microscopy and transmission electron microscopy. A technique was developed to determine the nitrogen concentration of an AA5083 composite from secondary ion mass spectrometry utilizing a nitrogen ionimplanted standard. Aluminum nitride and amorphous nitrogen-rich dispersoids were found in the nanocrystalline aluminum grain boundaries. Nitrogen concentration increased as a function of cryomilling time up to 72hours. A greater nitrogen concentration resulted in an enhanced thermal stability of the nanocrystalline aluminum phase and a resultant increase in hardness. The distribution of the nitrogen-rich dispersoids may be estimated considering their size and the concentration of nitrogen in the composite. Contributions to strength and ductility from the Orowan relation can be more accurately modeled with the quantified nitrogen concentration.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful technique for the analysis of organic surfaces and interfaces for many innovative technologies. However, despite recent developments, there are still many issues and challenges hindering the robust, validated use of ToF-SIMS for quantitative measurement. These include: the lack of metrology and fundamental understanding for the use of novel cluster primary ion beams such as C60ⁿ⁺ and Ar₂₀₀₀⁺; the need for validated and robust measurement protocols for difficult samples, such as those with significant micron scale surface topography; the lack of guidance on novel data analysis methods including multivariate analysis which have the potential to simplify many time-consuming and intensive analyses in industry; and the need to establish best practice to improve the accuracy of measurements. This thesis describes research undertaken to address the above challenges. Sample topography and field effects were evaluated experimentally using model conducting and insulating fibres and compared with computer simulations to provide recommendation to diagnose and reduce the effects. Two popular multivariate methods, principal component analysis (PCA) and multivariate curve resolution (MCR), were explored using mixed organic systems consisting of a simple polymer blend and complex hair fibres treated with a multi-component formulation to evaluate different multivariate and data preprocessing methods for the optimal identification, localisation and quantification of the chemical components. Finally, cluster ion beams C60ⁿ⁺ and Ar_500-2500⁺ were evaluated on an inorganic surface and an organic delta layer reference material respectively to elucidate the fundamental metrology of cluster ion sputtering and pave the way for their use in organic depth profiling. These studies provide the essential metrological foundation to address frontier issues in surface and nanoanalysis and extend the measurement capabilities of ToF-SIMS.

Au cours de ces travaux de thèse, nous avons étudié la redistribution atomique de contaminantsmétalliques dans le silicium et au voisinage d'une interface SiO2/Si. Pour mener à bien cetteétude, trois techniques de caractérisation complémentaires ont été utilisées (TEM,APT,SIMS).Nous avons dans un premier temps étudié la diffusion ainsi que la ségrégation d'équilibre de contaminants à une interface SiO2/Si, et plus particulièrement, la diffusion du W et du Mo. Le Wprésente une cinétique de diffusion extrêmement lente. Les caractérisations réalisées par TEM et APT nous ont permis de discuter les profils de concentrations mesurés par SIMS et nous ont guidés dans le choix du modèle de diffusion proposé. L'étude de la diffusion du Mo révéle que cette espèce présente une limite de solubilité faible dans le silicium et une forte interaction avec des défauts d'irradiation, provoquant sa précipitation.Dans un second volet, nous nous sommes intéressés à l'effet d'une interface mobile, lors d'une réaction, sur la redistribution atomique des contaminants proches de cette interface. Nous avons ainsiréalisé une étude comparative des comportements du Fe et W lors de procédés d'oxydation.Le tungstène précipite dans le volume et est progressivement rejeté par l'oxydation. Le ferprécipite à l'interface SiO2/Si, provoquant un effet de masquage dont nous avons montré qu'il étaitresponsable de la formation de défauts pyramidaux d'interface, caractéristiques d'une contaminationen fer du silicium. Le procédé de germano-siliciuration de nickel, réalisé à basses températures a également été investigué. Cette réaction provoque le rejet 3D du germanium à l'interface NiSiGe/SiGe. / During this thesis work, we studied the atomic redistribution of metallic contaminantsin silicon and near a SiO2/Si interface. To conduct this study, we used three complementary characterisation techniques : transmission electron microscopy (TEM), atomic probe tomography (APT) and secondary ion mass spectrometry (SIMS).We first studied the diffusion and equilibrium segregation of various contaminants at a SiO2/Si interface, and more particularly, the diffusion of W and Mo. W exhibits a very slow diffusion kinetic.Physico-chemical characterizations performed by TEM and APT allowed discussing the concentrationprofiles obtained by SIMS leading to the diffusion model that we proposed. The study of Mo diffusionrevealed that this specy exhibits a low solubility limit in silicon and strongly interacts with irradiation-induced defects, leading to its precipitation.In a second phase, we studied the effect of a mobile interface, during a reaction, on the atomic redistribution of contaminants near this interface. We performed a comparative study of the behaviourof Fe and W during oxidation processes. W precipitates in the silicon substrate and is progressivelyrejected (snowplow) by the oxidation. Fe preferentially precipitates at the SiO2/Si interface. Theseprecipitates mask a part of the silicon substrate and thus hinder its oxidation, leading to the formation of characteristics pyramidal-shaped defects at the interface. Low temperature nickel germano-silicide formation have also been investigated. This reaction leads to the 3D snowplow of germanium atoms at the NiSiGe/SiGe interface.