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<p>This thesis explores the ablation and texturing of synthetic single crystal diamond under ultrashort laser pulse irradiation in rough vacuum ambient conditions. Experiments were performed with a 1 kHz repetition rate titanium sapphire laser system producing pulses at 800 nm central wavelength and 150 fs pulse duration. First, the production of ordered periodic nanostructures (ripples) on the diamond surface was characterized and the periodicity of these structures was analyzed against irradiation parameters. Ripples were usually found to fall into one of two categories: one with a spatial period near the irradiation wavelength and one with a spatial period near λ/2n, where λ is the central laser wavelength in air and n is the refractive index of diamond at λ. The spatial periods were plotted against irradiation conditions including the peak fluence, number of incident pulses, and the angle of incidence. Unique outcomes arising out of complex irradiation conditions were also explored. Second, the ablation thresholds for single pulse up to 1000 pulse irradiation were determined using the <em>D</em>² method at both the fundamental central wavelength (800 nm) and the second harmonic (400 nm). The single 800 nm pulse ablation threshold for synthetic single crystal diamond was determined to be 2.3 J/cm² with an incubation coefficient of 0.54. The single 400 nm pulse ablation threshold was determined to be 1.5 J/cm² with an incubation coefficient of 0.73.</p> / Master of Applied Science (MASc)

No / A novel process chain for serial production of polymer-based devices incorporating both micro- and nano-scale features is proposed. The process chain is enabled by the use of Zr-based bulk metallic glasses (BMG) to achieve the necessary level of compatibility and complementarity between its component technologies. It integrates two different technologies, namely laser ablation and focused ion beam (FIB) milling for micro-structuring and sub-micron patterning, respectively, thus to fabricate inserts incorporating different length scale functional features. Two alternative laser sources, namely nano-second (NS) and pico-second (PS) lasers, were considered as potential candidates for the first step in this master-making process chain. The capabilities of the component technologies together with some issues associated with their integration were studied. To validate the replication performance of the produced masters, a Zr-based BMG insert was used to produce a small batch of micro-fluidic devices by micro-injection moulding. Furthermore, an experimental study was also carried out to determine whether it would be possible by NS laser ablation to structure the Zr-based BMG workpieces with a high surface integrity whilst retaining the BMG’s non-crystalline morphology. Collectively, it was demonstrated that the proposed process chain could be a viable fabrication route for mass production of polymer devices incorporating different length scale features.

Nanodiamonds are a promising platform for quantum technologies due to the combinations of their inherent properties and the properties of the fluorescent color centers hosted in diamond. They can be employed as quantum sensing devices with spatial resolution in the range of the nanometer and capable of withstanding harsh conditions while also being biocompatible, allowing applications with sensitive biological systems; but they also find application in quantum computing and photonics fields. For all these applications the central features are the properties of the photoluminescent color centers employed, the color centers on which this thesis is focused are the Nitrogen-Vacancy (NV) and Silicon-Vacancy (SiV) centers of diamond. Both centers are of high interest due to spin dependent properties of their fluorescent emission which can be accessed at room temperature. The development of quantum technologies based on such fluorescent nanodiamonds is stifled by the the lack of production techniques that can be easily scaled to industrial levels. In fact most of the more prominent techniques found in literature exhibit drawbacks both in terms of control of particle properties and of scalability. This thesis focuses on the synthesis of nanodiamonds by Pulsed Laser Ablation in Liquid, with particular interest in the possibility of producing continuously nanodiamonds containing NV and SiV centers. For the NV center the technique of choice have been Pulsed Laser Ablation in liquid nitrogen focusing on the yield of the process as the technique has already been experimentally validated. For the SiV centers the ablation process was performed in water and the graphite precursor have been substituted for a composite graphite and silicon carbide precursor.

Ferroelectric materials are characterized by a reversible spontaneous polarization in the absence of an electric field. The characteristic polarization response of a ferroelectric material to an applied electric field enables a binary state device in the form of a thin film ferroelectric capacitor that can be used to store digital information. This provides opportunities for the development of high speed, low cost and low power, nonvolatile memory devices. The development of commercial ferroelectric memory devices has however been hampered by (a) several reliability issues including fatigue, leakage current, aging, time dependent dielectric breakdown, retention and imprint and (b) processing problems including the development of a low temperature thin film deposition process and the development of a patterning technology. Lead zirconate titanate (PZT) is now widely considered as the most promising material for ferroelectric memory applications as a result of its excellent ferroelectric properties and wide operating temperature range. However, it is commonly found that metal electroded-PZT capacitors (e.g., Pt/PZT/Pt) show a loss of switchable polarization with cumulative switching cycles. This phenomenon is known as fatigue and is the one of the critical problems affecting the lifetime of ferroelectric memories. This research is primarily focused on the problem of fatigue. On the basis of a quantitative model, various guidelines to minimize the degradation problem have been derived. The model attributes fatigue to domain pinning by space charge that is caused by defect (e.g. oxygen vacancy) entrapment at various interface sites such as electrode-ferroelectric interface, domain boundaries and grain boundaries. Two different approaches to minimize the problem have been outlined : (a) control of the defect density and (b) control of the interface state. The control of interface state was achieved by replacing the metal electrodes with conducting oxide electrodes such as RuO₂. The oxide electrode/PZT capacitors were characterized for their diffusion barrier properties, perovskite phase formation, interface nature and ferroelectric properties. The results indicate that these oxide electroded PZT films are good candidates for nonvolatile memory applications. However, the leakage current levels at the operating voltages are far higher than the metal counterparts. Simultaneous minimization of fatigue and leakage current in PZT films was achieved by using multilayer metal/conducting oxide electrodes (e.g., Pt/RuO₂). The control of defect density was attained by (a) donor doping to compensate for the oxygen vacancies (e.g, Nb doping in PZT) and (b) utilizing ferroelectric materials that have a low intrinsic defect concentration. As a result of the latter approach, novel ferroelectric materials belonging to the layer-structure family of oxides have been identified as excellent candidates for fatigue free nonvolatile memory applications. Laser ablated SrBi₂(Ta_xNb_{1 - x})₂O₉ (0<x<1) films showed very good hysteresis characteristics (remnant polarization value of 11 µC/cm², coercive field of 60 kV/cm), no fatigue was observed up to 10⁹ switching cycles and very low leakage current densities. Furthermore, the formation and properties of these films were characterized. It was found grain size and orientation played a major role in determining the properties of these films. C-axis oriented films were found to exhibit almost no polarization. An additional objective of this research was to identify an etching technology (process integration issue) for patterning of the ferroelectric capacitors. The etching process should provide high etch rates, good etch anisotropy, high etch selectivity and minimal post etch residues. It has been shown that a reactive ion etch process with CCl₂F₂/O₂ as the etch gas mixture can meet these requirements. A detailed process study has been conducted to determine the mechanism of etching. / Ph. D.

Die Synthese kolloidaler Nanopartikel ist daher eines der wichtigsten Forschungsthemen der letzten Jahre. Die gepulste Laserablation in Flüssigkeiten stellt eine Alternative zu den nasschemischen Synthesewegen dar. Merkmale der gepulsten Laserablation in Flüssigkeiten ist der geringe experimentelle Aufwand, die Vielseitigkeit und die Möglichkeit stabilisatorfreie kolloidale Nanopartikel herzustellen. Eine Weiterentwicklung ist die Verwendung von Pulversuspensionen als Ausgangsmaterial. Dies führt zu höheren Produktivitäten und neuen Materialien. Die zugrundeliegenden Prozesse sind allerdings komplex. Um diese Mechanismen aufzuklären, wurde ein chemischer Ansatz gewählt. Als Ausgangsmaterial wurden daher verschiedene Kupferverbindungen (Cu2C2, Cu5Si, Cu3N, Cu(N3)2, Cu3P, Cu2O, CuO, Cu2S, CuS und CuI) verwendet. Die hergestellten Nanopartikel wurden mit Hilfe der analytischen Transmissionselektronenmikroskopie charakterisiert. Dadurch konnten nachgewiesen werden, dass zwei Mechanismen an der Nanopartikelbildung beteiligt sind. Die Laserbestrahlung von Ausgangsmaterialien wie CuO und Cu3N führt zur Bildung von metallischen Kupfernanopartikeln. In dem dabei erzeugten Plasma nukleieren die Kupferatome zunächst zu kleinen primären Nanopartikeln. Diese Partikel koaleszieren anschließend und bilden größere sekundäre Partikel. Im Gegensatz zu dieser reduktiven Ablation, resultiert die Laserbestrahlung von CuI in der Fragmentierung des Materials. In diesem Fall wird kein Plasma erzeugt, sondern der induzierte thermische Stress führt zur Fragmentierung des Kristalls unter Beibehaltung der chemischen Zusammensetzung. Die Frage, welcher der beiden Mechanismen für ein bestimmtes Ausgangsmaterial dominiert, ist entscheidend für potentielle Anwendungen der Methode, da hiervon die chemische Zusammensetzung der erhaltenen Nanopartikel abhängt. Dies wird am Beispiel der Synthese von Bi2Te3 Nanopartikeln diskutiert, die in thermoelektrischen Elementen zur Anwendung kommen können. / The synthesis of colloidal nanoparticles has become a major topic in recent years. The pulsed laser ablation in liquids poses an alternative to the common wet-chemical approaches. Key features of the pulsed laser ablation in liquids are its simple setup, its versatility, and the possibility to generate surfactant-free colloidal nanoparticles. A further development of this technique is the use of suspended powders instead of bulk targets. This leads to higher productivities and even new materials. Although the generation of colloids by irradiating a suspension is straight forward, the underlying mechanisms of the size reduction from micrometer to nanometer sized particles appear to be quite complex. In order to reveal the mechanism a chemical approach was chosen. Hence, various copper compounds (Cu2C2, Cu5Si, Cu3N, Cu(N3)2, Cu3P, Cu2O, CuO, Cu2S, CuS and CuI) were used as a model system in order to investigate the impact of the leaving group on the ablation process. The generated nanoparticles were characterized with analytical transmission electron microscopy. These investigations clearly show that there are two distinct mechanisms involved in nanoparticle formation. The laser irradiation of precursors like CuO and Cu3N results in the formation of metallic copper nanoparticles. In the generated plasma copper atoms nucleate and form small primary particles. These particles later coalesce to larger secondary particles. In contrast to this reductive ablation, the irradiation of CuI follows a fragmentation mechanism. Here, the absorbed power of the laser beam does not produce a plasma but introduces thermal stress leading to fragmentation of the crystal while the chemical composition is preserved. The question which mechanism is predominant is of utmost importance as the chemical composition of the nanoparticles depends on the formation process. This is discussed on the example of the synthesis of Bi2Te3 nanoparticles, which can be used in thermoelectric applications.

La datation de l’âge de génération des hydrocarbures et de la déposition de la roche mère fournit des informations importantes dans la prospection pétrolière. Dans ce travail, différentes stratégies ont été étudiées pour la détermination des métaux traces, et des rapports isotopiques du plomb dans des produits pétroliers par des techniques de spectrométrie de masse. Les stratégies d’analyses développées dans ce travail ont été utilisées pour estimer l’âge de génération du pétrole, ainsi que l’âge de déposition de la roche mère âge du « New Albany shales » dans le basin d’Illinois, en utilisant les géochronomètres U-Th-Pb. Les ages déterminés par la méthode U-Th-Pb sont en très bon accord avec ceux prédits par les modèles numériques géologiques, ce qui démontre le potentiel de cette approche pour étudier l’histoire de la formation des hydrocarbures et dans la recherche de nouvelles sources d'hydrocarbures. / Timing crude oil generation and source rock deposition provides important clues in petroleum prospection. In this work, different analytical procedures were developed for trace metals and Pb isotope ratio were determination crude oils and related products. These analytical strategies were then used, for the first time, to assess the applicability of the U-Th-Pb geochronometers for timing source rock deposition age and crude oil generation in the Illinois Basin. Ages determined are in good agreement with those predicted by geological numerical models, demonstrating the potential of these geochronometers to study the history of hydrocarbons formation and to find new hydrocarbon sources.