L'objectif de cette thèse était de développer de nouvelles méthodes micro- et nano-thermométriques proposant de hautes résolutions spatiales et temporelles. Dans ce cadre nous nous sommes concentrés sur deux tâches : dans un premier temps, nous avons développé un dispositif de nano-chauffage qui peut aisément servir à la caractérisation thermo-physique de matériaux à l'échelle nanométrique. Dans un second temps, en utilisant cette plate-forme nous avons étudié des matériaux thermosensibles, incluant divers luminophores et des complexes à transition de spin ainsi que leurs mélanges. Les dispositifs de nano-chauffage, basés sur des nanofils chauffés par effet Joule, ont été fabriqués par lithographie électronique conventionnelle. Grâce à leur faible inertie thermique, les dispositifs basés sur des nanofils sont particulièrement intéressants en termes de temps de réponse et de confinement des changements de température induits. La caractérisation thermique de ces éléments de chauffage a été réalisée à l'aide de méthodes électriques et optiques ainsi que de simulations par éléments finis. Nous avons montré expérimentalement que nos chauffages prodiguent des perturbations en température (1 K < DeltaT < 80 K) rapides (< µs) et spatialement localisées (< µm) lorsque stimulées par des impulsions de courant électrique. Les simulations par éléments finis reproduisent ces résultats expérimentaux avec une bonne précision et prouvent ainsi leur intérêt pour le design de tels dispositifs. Les performances thermométriques de matériaux fluorescents, incluant des colorants organiques (Rhodamine B), des nanoparticules inorganiques (PbF2:Er3+/Yb3+, CdSe) et des nanoparticules hybrides organiques/inorganiques ([Fe(Htrz)2(trz)]BF4@SiO2-pyrene), ont ensuite été étudiées. D'une manière générale, leur intérêt pour l'imagerie thermique a été démontré, mais des problèmes de stabilité rendent les mesures quantitatives difficiles avec de tels matériaux. D'un autre côté, nous avons réussi à synthétiser des films de nanoparticules du complexe à transition de spin [Fe(Htrz)2(trz)]BF4 (non-dopé). Ces films qui nous ont permis de suivre les changements de température à l'aide de mesures de réflectivité optique plus robustes. La boucle d'hystérèse thermique dans ce matériau procure un effet de mémoire thermique à long terme dont nous avons usé avec succès pour imager les changements de température très rapides (< µs) et spatialement localisés (< µm) - même après que la chaleur se soit dissipée. Cette méthode originale nous procure une combinaison sans précédent de sensitivité spatio-temporelle dans le champ de la nano-thermométrie aux applications pratiques prometteuses. / The overall objective of this PhD thesis was to develop novel micro- and nano-thermometry methods providing high spatial and temporal resolution thermal imaging. To achieve this goal we have focused on two tasks: First, we developed a nano-heater device that can be easily employed for the thermo-physical characterization of materials at the nanoscale. In a second time, using this platform we investigated thermo-sensitive materials, including different luminophores and spin crossover complexes as well as their mixtures. The nano-heater device, based on Joule-heated metallic nanowires, was fabricated by standard electron beam lithography. Due to their small thermal mass, nanowire based devices are particularly interesting in terms of response times and also in terms of confinement of the induced temperature changes. The thermal characterization of these heating elements was carried out using electrical and optical methods as well as finite element simulations. We have shown experimentally that our heaters can provide fast (< µs) and spatially well localized (< µm) T-jump perturbations (1 K < DeltaT < 80 K) driven by an electrical current pulse. Finite element simulations reproduced these experimental results with good accuracy and proved to be a powerful tool of prediction for the device design. Fluorescent materials, including organic dyes (Rhodamine B), inorganic nanoparticles (PbF2:Er3+/Yb3+, CdSe) and hybrid organic/inorganic nanoparticles ([Fe(Htrz)2(trz)]BF4@SiO2-pyrene), were then investigated for their thermometry performance. Overall, they were found useful for thermal imaging, but stability problems make quantitative measurements challenging with these materials. On the other hand, we have succeeded in synthesizing nanoparticle films of the (undoped) [Fe(Htrz)2(trz)]BF4 spin crossover complex, which allowed us to infer temperature changes through more robust optical reflectivity measurements. The thermal hysteresis loop in this material provides a long-term thermal memory effect which we used successfully to image very fast (˜µs) transient temperature changes with high spatial resolution (sub-µm) - even when the heat is dissipated. This original method provides an unprecedented combination of spatio-temporal sensitivity within the field of nanothermometry with promising potential applications.

Le développement des applications industrielles relatives aux nanotechnologies entraîne un accroissement du nombre et de la variété de déchets contenant des nanomatériaux générés par l'industrie, les consommateurs et les laboratoires de R&D. Des familles de matériaux émergents incorporant des nano-objets se développent de manière significative alors que l’adéquation des filières de fin de vie (recyclage et élimination) n’est que récemment évaluée vis-à-vis des risques potentiels liés aux nanomatériaux. Les nanocomposites - dont la fin de vie est susceptible d'être prise en charge par l'incinération - font l'objet de cette thèse. L’objectif est d’une part de connaître le devenir des nano-objets (incorporés dans le nanocomposite) lors de l’incinération du nanocomposite ; et d’autre part de connaître leur comportement dans la chambre de combustion. Les essais d’incinération ont été réalisés à l’échelle laboratoire dans un four tubulaire et un cône calorimètre spécialement modifiés dans le but de contrôler les paramètres clés de l’incinération. Les suivis temporels des concentrations en gaz et des concentrations en nombre de l’aérosol de combustion ainsi que l’imagerie en microscopie électronique nous ont permis d’étudier les émissions et la décomposition thermique. Par ailleurs, l’influence de différents paramètres tels que la température de combustion, l’oxygénation de l’échantillon, le taux d’incorporation et la nature du nano-objet incorporé, sur la nature des émissions, a été étudiée. Enfin, pour faciliter l’utilisation des résultats au niveau opérationnel, un arbre décisionnel a été proposé aux décideurs publics et aux exploitants d’unité d’incinération. / Nanocomposites have been widely studied and produced since the end of the nineties. These trendy materials containing nanomaterials are expected to end up in incineration waste plants due to the lack of specific recovery procedures. The aim of this work is to investigate the behavior and the fate of the nano-objects from nanocomposites during their incineration and to give insights on potential environmental risk related to the incineration of waste containing nanomaterials. Incineration tests have been performed at lab-scale using a specific tubular furnace and a cone calorimeter which have been modified in order to control the key incineration parameters within both the combustion and post-combustion zones. The influence of the nano-objects presence on the combustion mechanisms (aerosol release and decomposition) is investigated. It seems necessary to address the issue of the fate of nano-objects incorporated initially in the polymer: are they destroyed, do they undergo changes during their stay in the incinerator furnace, and where are they are released ? The combustion residues and the combustion aerosol (collected downstream the incinerator) have been characterized using various techniques devoted to the analysis of aerosols. Furthermore, it has been studied the influence of different parameters (temperature of combustion, oxygen rate, loading of nano-objects, type of nano-objects) on the nature of emissions. Finally, a decision tree has been proposed to decision-makers and incineration plant managers in order to facilitate the use of the results on an operational level.

Les verres métalliques sont des matériaux récents (≈ 50 ans), obtenus par refroidissement rapide d'un alliage en fusion. La structure amorphe de ces matériaux leur confère des propriétés particulières : une très grande résistance mécanique (limite à la rupture de l'ordre de 1,7 GPa pour des alliages base Zr), une déformation élastique de l'ordre de 2% mais pas ou peu de ductilité. Les compositions pouvant être élaborées à l’état amorphe, et, sous forme massive, sont en nombre limité. Le travail présenté dans ce manuscrit démontre la possibilité de consolider par frittage SPS (Spark Plasma Sintering), des poudres amorphes obtenues par atomisation (Фmoy.≈70 μm), tout en conservant majoritairement le caractère amorphe. L’optimisation de ce protocole, avec la composition Zr57Cu20Al10Ni8Ti5, a permis de retrouver le même comportement mécanique qu’un verre massif monolithe. Une cristallisation partielle du matériau se produit cependant aux points de contact des particules, mais pourrait être réduite en poursuivant le modèle de frittage esquissé dans ce manuscrit. Aux vues de ces résultats, la conception de nouvelles compositions, et leur élaboration sous forme de rubans, ont été menées. La caractérisation par nano-indentation permet d’estimer de manière fiable les propriétés mécaniques de ces alliages. Enfin, une nouvelle méthode d’évaluation du volume d’activation, qui est le volume élémentaire cisaillé initiant la déformation plastique, est présentée. Il s’agit de l’analyse statistique d’essais de pseudo-fluage en nano-indentation, réalisés à température ambiante. En conclusion, ce travail propose de nouvelles perspectives d’élaboration de verre métalliques sous forme massive dans une gamme de composition bien plus large / The metallic glasses are relatively new materials (≈ 50 years), produced by quenching a molten alloy. The amorphous structure of these materials gives them unique properties: very high strength (fracture stress is about 1.7 GPa for Zr based alloys), an elastic deformation reaching 2%, but little or no ductility. The compositions, which could produce both amorphous and bulk samples, are limited. The work, detailed in this manuscript, shows the possibility of sintering using SPS (Spark Plasma Sintering) amorphous powders obtained by atomization (Фaverage ≈ 70 microns). The result is a fully densified and near fully amorphous sample. The optimization of this technique, with the composition Zr57Cu20Al10Ni8Ti5, gave samples for which mechanical behaviour is close to the bulk metallic glass behaviour. However, partial crystallization of the material occurs, localized at the contact points of particles, but could be reduced by deepening the sintering model outlined in this manuscript. In view of these results, new compositions are designed, and the production of ribbons was conducted. The characterization by nano-indentation estimates reliably the mechanical properties of these alloys. Finally, a new method, evaluating the activation volume, which is the elementary volume initiating plastic deformation, is presented. This technique is a statistical analysis of pseudo-creep tests performed by nano-indentation, at room temperature. In conclusion, this work opens new perspectives to develop bulk samples in broad range of compositions

La production à l'échelle industrielle et la diversité d'utilisation des nano-objets manufacturés, leurs agrégats et agglomérats (NOAA) et leur possible libération dans l'environnement aquatique naturel ont conduit à une préoccupation croissante parmi la communauté scientifique des sciences de l'environnement et des nanotechnologies. Parmi eux, les ciments photocalytiques sont basés sur la propriété photocatalytique de NOAA-TiO2 ajoutés dans la matrice du ciment. Lors de l'exposition au rayonnement UV, les NOAA-TiO2 provoquent l‘oxydation (i.e. dégradation) des composés adsorbés à la surface du ciment. Sa validation environnementale est requise, en termes d'impacts et risques associés à l'incorporation des NOAA-TiO2. Le but de cette étude est de déterminer les mécanismes de relargage des NOAA-TiO2 incorporés dans le ciment autonettoyant durant le processus de vieillissement et d’identifier les paramètres qui pourraient le contrôler. Les éléments relargués (fractions particulaires et solubles) et leurs cinétiques ont été quantifiés par ICP-OES et caractérisés par MET. Nous avons ensuite analysé la phase solide (du cœur à la couche altérée) en utilisant plusieurs techniques aux rayons X, la DRX (diffraction des rayons X), μ-XRF (micro X-Ray spectroscopie) et une combinaison sans précédent de nano et micro X-ray tomographie pour effectuer une caractérisation complète de la matrice du ciment altéré comprenant la structure de pores. / The industrial scale production and wide variety of applications of manufactured nano-object, their aggregates and agglomerates (NOAA) and their possible release into the natural aquatic environment have produced an increasing concern among the nanotechnology and environmental science community.Among them, the photocatalytic cements are based on the photocatalytic property of TiO2-NOAA added in the cement matrix. During continuous UV radiation exposure, TiO2-NOAA lead to the oxidation (i.e. degradation) of compounds adsorbed at the cement surface. Such NOAA application in building construction is promising as it exhibits improved properties but its environmental validation (in terms of impacts and risks associated with the incorporation of TiO2 NOAA) is also required.The aim of this study is to determine the mechanisms of TiO2-NOAA release from a self-cleaning cement during aging process and to identify cement parameters controlling it.. The elements released (particulate and soluble fractions) and their kinetic were quantified by ICP-OES and characterized with TEM. We analyzed the solid phase (core to altered layer) using several X-ray based techniques: XRD (X-Ray Diffraction), µ-XRF (micro X-Ray Spectroscopy) and an unprecedented combination of nano and micro X-ray computed tomography to perform a original and omplete altered cement matrix characterization including pore structure.

Neste trabalho estudamos o efeito SERS de moléculas adsorvidas em sistemas eletroquímicos em termos da participação do mecanismo de transferência de carga na intensificação total observada. Desenvolvemos um modelo para o mecanismo químico de transferência de carga assitido por fótons, de maneira a explicar a variação do potencial de máxima intensificação SERS (Vmax) com a energia da radiação excitante. O modelo permite também o uso da expressão para o espalhamento Raman no domínio do tempo para o cálculo de perfis de excitação SERS (intensidade SERS versus potencial aplicado) de moléculas adsorvidas em interfaces eletroquímicas. Este método de cálculo dos perfis de excitação SERS foi aplicado para os casos da piridina e do íon complexo [Fe2(CN)104,4\'-bpy]6- em eletrodo de prata. Os resultados mostram existir uma boa relação entre os perfis calculados e os obtidos experimentalmente. Como resultado dos cálculos efetuados, o modelo fornece ainda dados sobre o deslocamento das curvas de poço potencial dos estados excitados envolvidos nos processos de transferência de carga assistidos por fótons. Nos capítulos seguintes, estudamos algumas conseqüências deste modelo, e sua aplicação em diferentes sistemas químicos. Um dos sistemas estudados foi o íon complexo [Ru(bpy)2viol]+ adsorvido em eletrodo de prata. Observa-se que a intensidade relativa dos modos vibracionais de cada um dos ligantes varia com o potencial aplicado ao eletrodo. Esses resultados podem ser explicados considerando-se dois processos de transferência de carga superficie &#8594; adsorbato assistidos por fótons. O primeiro deles deve-se a uma transição envolvendo estados doadores próximos ao nível de Fermi do metal (EF) e estados receptores (orbitais &#960;*) localizados no violurato. O segundo envolve estados doadores em EF e orbitais &#960;* da bpy. A energia da transição de transferência de carga metal &#8594; adsorbato varia com o potencial aplicado. Existe portanto a possibilidade de se alcançar diferentes estados eletrônicos excitados do adsorbato, intensificando, seletivamente, diferentes cromóforos com um único comprimento de onda. Assim, através da variação do potencial aplicado ao eletrodo é possível modular a transição de transferência de carga Ag &#8594; complexo de modo a envolver cada um dos diferentes ligantes. Estudamos também o mecanismo envolvido no efeito SERS da molécula FePc (ftalocianina de ferro) em eletrodo de prata. Nesse sistema, foi possível apresentar uma versão mais detalhada para o efeito químico envolvido na intensificação SERS incluindo o efeito de múltiplos estados excitados e acoplamento vibrônico, enfatizando as relações de simetria e overlap de funções de onda que regem os mecanismos de intensificação Raman ressonante. A excitação dos espectros SERS em comprimentos de onda fora da condição de Raman ressonante pode intensificar modos vibracionais de simetria a2g (não permitidos no espectro Raman normal) desde que o potencial aplicado esteja próximo à condição de ressonância para uma transição de transferência de carga superficie/adsorbato. O mecanismo químico de intensificação envolvido no efeito SERS desse sistema pode ser descrito como um processo de transferência de carga modulado pelo potencial, envolvendo dois estados doadores da FePc e um estado aceptor localizado na superficie do eletrodo de prata. Enquanto os modos totalmente simétricos (a1g) são intensificados por um mecanismo de Franck-Condon, os modos a2g têm a simetria apropriada para acoplar dois estados eletrônicos de simetria A1u e A2u, sendo intensificados através do mecanismo de Herzberg- Teller. Os efeitos da natureza química do solvente, e das interações solvente-soluto nas geometrias de adsorção e nas posições dos estados eletrônicos do adsorbato, são analisados para os ciano complexos Fe(phen)2(CN)2 e [Fe2(BPE)(CN)10]6-. Os resultados obtidos demonstram a influência decisiva da natureza química de solventes e eletrólitos suporte na espectroscopia de espécies adsorvidas em interfaces eletroquímicas. De fato, a natureza das interações solvente-adsorbato ou eletrólito-adsorbato podem determinar a ligação à superficie, e, desta maneira, intensificação seletiva de modos vibracionais da molécula pode ser obtida. A partir do estudo do processo de transferência de carga entre a superficie e os complexos adsorvidos através dos perfis de excitação SERS foi possível, em alguns casos, mapear os níveis de energia do adsorbato com relação ao nível de Fermi do metal. / In this work, attention has been given to systems in which the charge transfer (CT) mechanism is contributing to the enhancement of the Raman scattering of species adsorbed on metal surfaces in order to address the participation of a resonance Raman effect on this part of the total enhancement. A model for the adsorbate-metal surface interaction and the charge transfer mechanism for surface-enhanced Raman scattering (SERS) is presented. The fundamental observation behind the currently proposed model is that ali previous theories indicate that Raman intensity should be at maximum when the incident laser frequency is resonant with a surface/adsorbate charge transfer band. This fact leads to the conclusion that this aspect of the chemical effect may be due to a resonance Raman mechanism. Therefore, for such mechanism to be valid, the chemical effect of SERS must follow the already well established principies of resonance Raman theory. In this model, the metal surface provides a source of electrons that may, upon interaction with light, flow into and out of the adsorbed species. Based on this model we have proposed a formalism derived from the time-domain description of the resonance Raman effect that describes the dependence of the SERS intensities of molecules adsorbed in electrochemical interfaces upon the applied potential. This approach accounts for the enhancement of totally symmetric modes via a Franck-Condon mechanism, and only one electronic excited state of the adsorbate/surface system is considered. The analytical expression derived to calculate the SERS intensity versus applied potential profiles and their dependence on the exciting radiation has been applied for pyridine and for the ion complex [Fe2(CN)10bpy]6- adsorbed on a silver electrode. A good agreement between calculated and experimental excitation profiles have been obtained for both investigated species. Resonance Raman spectroscopy is also an electronic spectroscopy, and, as presented in this work, the SERS effect, or part of it, is also an electronic spectroscopy. Its intensity contains, therefore, information about the structure of the excited electronic state involved in the charge transfer process. This information is provided by the calculation of the SERS excitation profiles according to the derived expression in the form of &#916;K values. The remaining sections of this work are dedicated to the study of the SERS effect of coordination compounds adsorbed on silver electrodes. One of the investigated systems is the mixed ligand ion complex [Ru(bpy)2viol]+. The SERS measurements have shown that the vibrational modes of both ligands can be selectively enhanced by changing the electrochemical applied potential at a fixed laser excitation energy. This result indicates the presence of two different metal to adsorbate photon assisted charge transfer processes. The first one involves a density of donor states near the Fermi level (EF) of the metal and na acceptor state localized on the violurate ligand, while the second process involves na acceptor state localized on the bpy ligand. These results demonstrate the possibility of reaching different excited electronic states of molecules adsorbed on electrode surfaces, selectively enhancing different chromofores by changing the applied potential and of assigning electronic charge transfer transitions based on SERS results. In order to provide a more detailed description of the charge transfer mechanism of enhancement working in the SERS effect of adsorbed molecules, including the role of multiple excited electronic states, vibronic coupling and symmetry selection rules, the SERS effect of iron phthalocyanine is discussed. The charge transfer mechanism of enhancement in this system is characterized as a potential modulated charge transfer process involving two donor states at the FePc and an acceptor state at the silver electrode surface. Excitation of the SERS spectra at wavelengths off resonance with the Q-band may enhance the a2g vibrational modes (non allowed modes at normal Raman condition), via a Herzberg-Teller mechanism, providing that the applied potential is dose to the resonance condition for the adsorbate to metal charge transfer transition. The effects of the chemical nature of the solvent in the adsorption geometry and in the position of the electronic states of adsorbates is discussed for the cyano complexes Fe(phen)2(CN)2 and [Fe2(BPE)(CN)10]6-. The results obtained have demonstrated the decisive role played by the chemical nature of solvents and supporting electrolytes in the surface-enhanced spectroscopy of species adsorbed at electrochemical interfaces. In fact, the nature of solvent or electrolyte - molecule interaction can determine the bonding to the surface, and therefore, selective enhancement of vibrational modes within a molecule can be accomplished. Based on the charge transfer processes between the surface and the adsorbed molecules probed by the SERS excitation profiles, it has been possible, in some cases, to determine the position of the energy levels of the adsorbate in relation to the Fermi level of the metal electrode.

This master`s thesis is focused on modern cutting finishing methods of outer surfaces. In the first part the cutting finishing technologies of outer surfaces are analysed, which is followed by a description of modern finishing methods from the fine machining up-to the nano-machining. The experimental part includes the analysis of surface roughness during front turning of a dural disc and the study of magnitudes of forces during its longitudinal turning. The thesis contains technological-economic evaluation of the achieved results.

La synthèse contrôlée de nano-alliages de germaniure de fer a connu un regain d'intérêt grâce à la récente découverte de nouvelles applications dans le domaine du stockage d'informations. Toutefois, la chimie du couple fer-germanium est une chimie complexe qui reste peu étudiée. Ces travaux de thèse associent chimie moléculaire et chimie des nano-objets pour explorer les potentialités de précurseurs mono-sources pour la synthèse en solution et en conditions douces de NPs de germaniure de fer. Dans un premier temps, nous nous sommes intéressés à la formation de nouveaux complexes présentant une architecture de type amidinatogermylène offrant un équilibre entre la stabilisation des complexes et leurs températures de décomposition, par exemple les complexes mono-germylène fer {[iPrNC(tBu)NiPr]GeCl}Fe(CO)4 et {[iPrNC(tBu)NiPr]GeHMDS}Fe(CO)4 ou le complexe bis-germylène fer {[iPrNC(tBu)NiPr]GeCl}2Fe(CO)3. Dans un second temps, nous montrons que cette méthode constitue une voie de choix permettant la formation de nano-alliages de germaniure de fer et que l'architecture des précurseurs mono-sources permet d'obtenir un contrôle sur les nanoparticules finales. En particulier, la décomposition à 200°C du complexe {[iPrNC(tBu)NiPr]GeHMDS}Fe(CO)4 conduit à la formation de nanoparticules sphériques de phase Fe3,2Ge2, de 6,5 ± 0,8 nm, présentant un comportement ferromagnétique. / Controlled synthesis of nano-alloys of iron germanide has gained a renewed interest thanks to the recent discovery of new applications in the field of information storage. However, the chemistry of the iron-germanium pair is a complex chemistry that remains little studied. The work presented in this thesis combines molecular chemistry and nano-object chemistry to explore the potential of single-source precursors for solution synthesis, in soft conditions, of iron germanium NPs. First, we focused on the formation of new complexes with an amidinatogermylene-type architecture offering a balance between the stabilization of complexes and their decomposition temperatures, for example mono-germylene iron complexes {[iPrNC(tBu)NiPr]GeCl}Fe(CO)4 and {[iPrNC(tBu)NiPr]GeHMDS}Fe(CO)4 or the bis-germylene iron complex {[iPrNC(tBu)NiPr]GeCl}2Fe(CO)3. In a second step, we show that this method represents a path of choice to reach the formation of nano-alloys of iron germanide and that the architecture of the mono-source precursors allows to control the final nanoparticles. In particular, the decomposition at 200°C. of the {[iPrNC(tBu)NiPr]GeHMDS}Fe(CO)4 complex leads to the formation of Fe3,2Ge2 spherical nanoparticles, with a mean diameter of 6.5 ± 0.8 nm, exhibiting a ferromagnetic behavior.

Zinc oxide (ZnO) is a well-known II-VI semiconductor material that has gained renewed interest in the past decade due to the developments of growth technologies and the availability of high-quality ZnO bulk single crystals. Owing to a wide direct band gap (3.37 eV), large exciton binding energy (60 meV), and high electron mobility (440 cm2 V-1 s-1), ZnO has been used for applications including actuators, optoelectronics, and sensors. ZnO nanoparticles can be synthesized in a broad variety of morphologies, such as nanotetrapods, nanotubes, and nanowires. Among these nanostructures, the tetrapods have attracted significant attention due to their unique morphology consisting of four legs connected together in a tetrahedral symmetry. Recently, it has been reported that nano-microstructured ZnO tetrapods (ZnO-Ts) can be synthesized by flame transport synthesis (FTS) in a rapid and up-scalable approach. Compared to conventional ZnO nanoparticles, the nano-microstructured ZnO-Ts can reduce cellular uptake, while still exhibiting specific nanomaterial properties due to the nanoscale tips. Moreover, the anisotropic ZnO-Ts have the advantages of multiple electron transfer paths, chemical stability, and biocompatibility, which make the ZnO-Ts promising candidates for biomolecule sensing applications. This work herein reports a systematical study on the structural, optical and electrochemical properties of the ZnO-Ts, which were synthesized by FTS using precursor Zn microparticles. The morphology of the ZnO-Ts was confirmed by scanning electron microscopy (SEM) as joint structures of four single crystalline legs, of which the diameter of each leg is 0.7-2.2 μm in average from the tip to the stem. The ZnO-Ts were dispersed in glucose solutions to study the photoluminescence as well as photocatalytic activity in a mimicked biological environment. The photoluminescence (PL) intensity in the ultraviolet (UV) region decreased with linear dependence on the glucose concentration up to 4 mM. The ZnO-Ts were also attached with glucose oxidase (GOx) and over coated with Nafion® to form the active media for electrochemical glucose sensing. The active layers were confirmed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, the current response of the active layers to glucose was studied by cyclic voltammetry (CV) in various glucose concentration conditions. Stable current response to glucose was detected with linear dependence on the glucose concentration up to 12 mM, which confirms the potential of ZnO-Ts for biomolecule sensing applications.

Physics and potential applications of femtosecond laser pulses interacting with matter have captured interest in various fields, such as nonlinear optics, laser micromachining, integrated optics, and solar cell technologies. On the one hand, such ultrashort intense pulses make them practical elegant tools to be utilized for direct structuring of materials with high accuracy and numerous potential applications. On the other hand, studying the fundamental aspects and nonlinear nature of such interactions opens new remarkable venues for various unique investigations. In recent years, the emerging topic of structured light (also known as twisted or optical vortex light), i.e., a beam of light with a twisted wave-front that can carry orbital angular momentum (OAM), has attracted the attention of many researchers working in the field of light-matter interaction. Such beams offer various applications from classical and quantum communication to imaging, micro/nano-manipulation, and modification of fundamental processes involved in light-matter interactions, e.g., absorption and emission. Nevertheless, the fabrication of complex structures, controlled modification, and achieving a high spatial resolution in material processing still remain in the spotlight. Moreover, the fundamental role of orbital angular momentum in the nonlinear absorption of materials, particularly in solids, has yet remained a subject of debate. Addressing these points was the main motive behind this dissertation. To accomplish this objective and investigate new aspects of structured light-matter interaction, I conducted various experiments, the results of which are presented in this work. The general idea was to study the interaction of femtosecond laser radiation, having a structured phase and polarization, with the matter in two aspects: (i) surface morphology modification and (ii) nonlinear absorption of solids. In this regard, I studied surface processing of crystalline silicon and CVD diamond with femtosecond laser vortex pulses generated by a birefringent phase-plate, known as q-plate, in single and multiple pulse irradiation regimes, respectively. The characterization of the modified region was performed using optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). I demonstrated that upon irradiation of a single vortex pulse on silicon, a nano-cone structure is formed within the ablated crater, whose height was independent of the helicity of the twisted light. However, for a linearly polarized vortex pulse, the height of the nano-cone decreases at higher pulse energies. The dynamics of nano-cone formation and the role of polarization were also investigated by simulating the mass transport function in this process. Moreover, using superimposed vortex beams, we fabricated complex patterns containing several nano-cones, by single-shot irradiation on the silicon surface. My experimental results offer an ability to actively control and manipulate material, in terms of the nanocones position, in two dimensions with an ultra-high resolution. I further proceeded with our experiments in the multiple pulse regime on a diamond target. By irradiation of a high number of superimposed vortex pulses, I was able to imprint complex polarization states of structured light on the target surface in the form of periodic nano-ripples. This procedure enabled us to not only generate spatially varying nano-gratings but also directly visualize and study very complex states of polarization. Besides these surface structuring, I carried out experimental studies to investigate the response of bulk material to an incident circularly polarized vortex beam that carries orbital angular momentum. The experimental results reveal, for the first time, that such an interaction can produce a differential absorption that gives rise to helical dichroism. We demonstrate that this response is sensitive to the handedness and degree of the twist in the incident vortex beam. Such a dichroism effect may be attributed to the excitation of dipole-forbidden atomic transitions, e.g., electric quadrupole transitions. However, this explanation is not absolute and remains open to further research and investigations.

Magnetic data storing has been of great interest since 1950 when the first magnetic hard drive was fabricated. A lot has happened since then, but there is still a need for smaller and cheaper devices.  One way to achieve this is by creating nano-sized ferromagnetic areas in a thin film at room temperature, or nano-magnets. In this thesis, the aim is to fabricate and characterize novel amorphous nano-magnets. Using a chromium mask ions can be implanted in a nano-sized pattern in an amorphous iron zirconium thin film. The mask is fabricated by depositing chromium over the iron zirconium and etching the nano-structures into the chromium film.  This requires the parameters for the etching to be optimized. It is discovered the parameters change with the size and shape of the pattern. Magnetization and structural characterization were performed by using the magneto-optical Kerr effect and a magnetic force microscope. The result shows that the nano-magnets become magnetically harder than the reference sample. The study further reveals structural details for further improvements in implanted regions. / <p>Opponent: Stivan Sabir</p>