De nos jours, réussir à contrôler la microstructure de la phase active des catalyseurs hétérogènes reste encore un défi d’envergure. Le présent travail s’inscrit dans cette mouvance en proposant de valoriser l’utilisation de clusters moléculaires comme précurseurs métalliques. Ces entités organométalliques comprenant au moins trois atomes métalliques (identiques ou non) en leur cœur apparaissent comme des candidats de choix pour contrôler la taille et la composition chimique des particules métalliques supportées à l’échelle nanoscopique. L’objectif de la présente thèse est de déterminer si l’utilisation de clusters moléculaires en présence d’un support carboné approprié permet d’obtenir ce contrôle. Tout d’abord, des clusters carbonylés de palladium de la littérature ont été synthétisés et une nouvelle voie de synthèse en une étape de ces entités a été découverte. Ensuite, le support carboné de départ a été dérivatisé afin d’y introduire des sites d’ancrage pour les clusters (phosphines chélatantes). Dans la troisième partie du travail, les clusters synthétisés ont été incorporés sur le support fonctionnalisé et sur celui de départ. L’obtention de nanoparticules supportées bien dispersées a démontré l’intérêt d’utiliser des clusters moléculaires comme précurseurs en présence d’un support fonctionnalisé. Les mécanismes d’ancrage ont également été étudiés et il a été prouvé que les clusters se fixent au support de manière covalent par échange de ligands. Enfin, les clusters supportés ont été activés et les catalyseurs Pd/C formés ont été testés dans l’hydrogénation du nitrobenzène en aniline. Les catalyseurs se trouvent être actifs dans cette réaction mais aucune corrélation « structure-activité » n’a pu être mise en évidence.

This work focuses on the surface and interfacial characterisation of silane films of a non-organofunctional silane, 1,2-bis(triethoxysilyl)ethane (BTSE), and an organofunctional silane, γ-mercaptopropyltrimethoxysilane (γ-MPS), deposited on Al, Zn and Al-43.4Zn-1.6Si (AlZn) alloy coated steel. Furthermore, a tribological study of a vegetable oil coupled to an aluminium surface pre-treated with γ-MPS is presented and, finally, the tribological response of thin organic coatings exposed to a sliding contact as evaluated by surface analysis is discussed. The main analyses techniques used were time-of-flight secondary ion mass spectrometry (ToF-SIMS), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). The results presented in this thesis show that the combination of ToF-SIMS, AES and XPS analysis can be used in order to obtain useful and complementary information regarding the surface and interface characteristics of silane films and organic coatings deposited on metal substrates. The major result regarding the silane films is that the silane film composition/structure is not dependent of pH-value during deposition or type of metal substrate. The presence of Si-O-Me ion fragments in the ToF-SIMS spectra is a strong indication that a chemical interaction between the silane film and the metal substrate exists. Furthermore, it has been shown that it is possible to bond a vegetable oil to a thiol functionalised aluminium surface and to produce a coating thick enough to obtain desired friction and wear characteristics. Finally, the use of ToF-SIMS analysis makes it possible to distinguish between mechanical and tribochemical wear mechanisms.

Cluster ToF-SIMS (time-of-flight secondary ion mass spectrometry) operated in the event-by-event bombardment/detection mode has been applied to: 1) evaluate and screen the manufacturing quality of step-wise prepared micropatterned biointerfaces; 2) quantify the binding density of Au nanoparticles (AuNPs)-antiCD4 conjugates selectively attached on the cell surface; 3) elucidate the biological interaction of proteins and molecules by quantifying the fractional coverage of immobilized biomolecules; 4) enhance the accuracy of secondary ion identification of specific molecules. Briefly, our method consists of recording the secondary ions, SIs, individually emitted from a single projectile impact (C60 1,2+, Au400 +4). From the set of individual mass data, we select events where a specific SI was detected. The selected records reveal the SIs co-ejected from the nanovolume impacted by an individual cluster projectile from an emission area of 10-20 nm in diameter and an emission depth of 5-10 nm. The approach for quantifying the number of AuNPs or that of specific nanodomains is via the concept of the fractional coverage. The latter is the ratio of the effective number of projectile impacts on a specified sampling area (Ne) to the total number of impacts (No). The methodology has been validated with the determination of the number of antibody-AuNP conjugates on a cell, i.e. the number of disease related antigens on a cell via their specific binding sites with the AuNP-labeled antibodies. The number of AuNP-antibodies measured, ~42000 per cell, is in good agreement with literature results. The fractional coverage concept was also used to quantify several variants of biointerfaces. An example is the quantification of biotin and avidin immobilization as a function of the composition of silane substrates. The data collected in the event-by-event bombardment/detection mode expands the scope and quality of analytical information. One can identify SIs co-emitted with two specified SIs (double coincidence mass spectrometry) to inspect a specific stratum of a biointerface. A further refinement is the selection of events meeting a double coincidence emission condition. This mode enables the identification of nano-object of a few nm in size, which eliminates (anticoincidence) interferences from substrates.

In this work the methodology is developed to study spreading and penetration of a custom ink-jet ink formulation, containing hydrophobic cationic crystal violet dye, ethoxylated surfactant, and ink solvent marked by lithium salt. With a new technique utilizing Time-of-Flight Secondary Ion Mass Spectrometry imaging, the ink component distribution and its effect on print quality of uncoated and coated papers are evaluated. High spatially resolved images obtained by ToF-SIMS illustrate differentiation of individual ink components, with ink solvent spreading more than the dye in all paper samples. Uncoated papers show greater and more irregular spreading leading to poor edge definition and poor print quality. Large separation of the dye from the solvent in the vertical direction of multipurpose and photo glossy ink-jet paper suggests a step-wise progression of ink penetration: ink flows through a more porous structure in the x-direction before advancing to the next sublayer in the z-direction of paper.

In this work the methodology is developed to study spreading and penetration of a custom ink-jet ink formulation, containing hydrophobic cationic crystal violet dye, ethoxylated surfactant, and ink solvent marked by lithium salt. With a new technique utilizing Time-of-Flight Secondary Ion Mass Spectrometry imaging, the ink component distribution and its effect on print quality of uncoated and coated papers are evaluated. High spatially resolved images obtained by ToF-SIMS illustrate differentiation of individual ink components, with ink solvent spreading more than the dye in all paper samples. Uncoated papers show greater and more irregular spreading leading to poor edge definition and poor print quality. Large separation of the dye from the solvent in the vertical direction of multipurpose and photo glossy ink-jet paper suggests a step-wise progression of ink penetration: ink flows through a more porous structure in the x-direction before advancing to the next sublayer in the z-direction of paper.

Biocatalysts are important tools for harnessing the potential of wood fibres since they can perform specific reactions with low environmental impact. Challenges to bioconversion technologies as applied to wood fibres include low accessibility of plant cell wall polymers and the heterogeneity of plant cell walls, which makes it difficult to predict conversion efficiencies. White-rot fungi are among the most efficient degraders of plant fibre (lignocellulose), capable of degrading cellulose, hemicellulose and lignin. Phanerochaete carnosa is a white-rot fungus that, in contrast to many white-rot fungi that have been studied to date, was isolated almost exclusively from fallen coniferous trees (softwood). While several studies describe the lignocellulolytic activity of the hardwood-degrading, model white-rot fungus Phanerochaete chrysosporium, the lignocellulolytic activity of P. carnosa has not been investigated. An underlying hypothesis of this thesis is that P. carnosa encodes enzymes that are particularly well suited for processing softwood fibre, which is an especially recalcitrant feedstock, though a major resource for Canada. Moreover, given the phylogenetic similarity of P. carnosa and P. chrysosporium, it is anticipated that the identification of pertinent enzymes for softwood degradation can be more easily conducted. In particular, this project describes the characterization of P. carnosa in terms of the growth conditions that support lignocellulolytic activity, the effect of enzymes secreted by P. carnosa on the chemistry of softwood feedstocks, and the characterization of the corresponding secretome using proteomic techniques. Through this study, cultivation methods for P. carnosa were established and biochemical assays for protein activity and quantification were developed. Analytical methods, including FTIR and ToF-SIMS were used to characterize wood samples at advancing stages of decay, and revealed preferential degradation of lignin in the early stages of growth on all softwoods analyzed. Finally, an in depth proteomic analysis of the proteins secreted by P. carnosa on spruce and cellulose established that similar sets of enzyme activities are elicited by P. carnosa grown on different lignocellulosic substrates, albeit to different expression levels.

Biocatalysts are important tools for harnessing the potential of wood fibres since they can perform specific reactions with low environmental impact. Challenges to bioconversion technologies as applied to wood fibres include low accessibility of plant cell wall polymers and the heterogeneity of plant cell walls, which makes it difficult to predict conversion efficiencies. White-rot fungi are among the most efficient degraders of plant fibre (lignocellulose), capable of degrading cellulose, hemicellulose and lignin. Phanerochaete carnosa is a white-rot fungus that, in contrast to many white-rot fungi that have been studied to date, was isolated almost exclusively from fallen coniferous trees (softwood). While several studies describe the lignocellulolytic activity of the hardwood-degrading, model white-rot fungus Phanerochaete chrysosporium, the lignocellulolytic activity of P. carnosa has not been investigated. An underlying hypothesis of this thesis is that P. carnosa encodes enzymes that are particularly well suited for processing softwood fibre, which is an especially recalcitrant feedstock, though a major resource for Canada. Moreover, given the phylogenetic similarity of P. carnosa and P. chrysosporium, it is anticipated that the identification of pertinent enzymes for softwood degradation can be more easily conducted. In particular, this project describes the characterization of P. carnosa in terms of the growth conditions that support lignocellulolytic activity, the effect of enzymes secreted by P. carnosa on the chemistry of softwood feedstocks, and the characterization of the corresponding secretome using proteomic techniques. Through this study, cultivation methods for P. carnosa were established and biochemical assays for protein activity and quantification were developed. Analytical methods, including FTIR and ToF-SIMS were used to characterize wood samples at advancing stages of decay, and revealed preferential degradation of lignin in the early stages of growth on all softwoods analyzed. Finally, an in depth proteomic analysis of the proteins secreted by P. carnosa on spruce and cellulose established that similar sets of enzyme activities are elicited by P. carnosa grown on different lignocellulosic substrates, albeit to different expression levels.

Some collision cascades, induced by keV polyatomic projectiles, result in the emission of multiple secondary ions. Such co-emissions imply that the ejecta originate from molecules co-located within the nano-volume perturbed by a single projectile impact. The relevance for the chemical analysis of nano-domains depends on the effectiveness of the projectile to cause co-emission of two or more secondary ions. This research examines how projectile characteristics, i.e. the energy and number of constituent atoms in the projectile, influence multiple secondary ion emission, or "superefficient" events. In addition we examine the relevance of this technique for nanostructure investigation. Yields have been measured for multi-ion emission events as a function of projectile characteristics. The data show that some collision cascades are "superefficient". For example, in a four-ion emission event, the yield for the phenylalanine quasi-molecular ion is two orders of magnitude larger from Au4+ impacts than from equal velocity Au+ projectiles. Yields for the co-emission of two phenylalanine quasi-molecular ions from "super-efficient" events have been measured. This case is particularly productive in that the detection of two analytically significant ions is recorded from a single event. Large increases (one to two orders of magnitude) in co-emitted ion yields were observed with increasing projectile energy and complexity. Correlation coefficients were calculated for the co-emission of two Ph ions, their behavior suggests differences in emission pathways for bombardment by atomic and polyatomic projectiles. Finally, we use this methodology to investigate surface structural effects on the occurrence of "super-efficient" events. The results indicate that it is possible to distinguish between two phases of a chemical compound although the stoichiometry remains the same. These results confirm previous predictions concerning the chemical nature of these "super-efficient" events. Also shown is that they are sensitive to the surface nanoenvironment. This approach extends the technology of Secondary Ion Mass Spectrometry by providing a methodology for probing surface nano-domains at the sub100 nm level.

No description available.

Les dispositifs avancés pour la microélectronique intègrent divers matériaux et sont de dimensions nanométriques. Une connaissance précise de leur composition est requise pour améliorer leurs procédés de fabrication et comprendre leur comportement électrique. Le ToF-SIMS est un candidat intéressant, qui souffre cependant des effets de matrice et ne possède pas toujours une résolution spatiale suffisante. Le but de ce travail est de permettre une analyse quantitative et résolue en profondeur de matériaux et structures pour la microélectronique avancée à l'aide d'un ToF-SIMS standard. Cette étude porte sur SiGe, sur des matériaux à haute permittivité, des implants basse énergie et des matériaux organiques. Elle se concentre sur la préparation d'échantillons, l'optimisation des conditions expérimentales et le traitement de données pour mettre au point des protocoles d'analyse originaux dont la précision est évaluée grâce à d'autres techniques de caractérisation de pointe. Ces protocoles permettent d'améliorer la qualité des analyses en termes de résolution en profondeur, de précision et de reproductibilité