In the present work studies were performed to provide understanding for further model development of the two-phase phenomena, film formation from o/w emulsions and slag foaming. The drying of o/w emulsions of different oil viscosities on hydrophobic and hydrophilic substrates was studied. The hydrophobic substrate was found to destabilise the oil droplets and to result in a different mechanism for forming continuous oil film. Studies of adsorption behaviour of a series of non-ionic diblock copolymers at relevant interfaces showed that the adsorption behaviour at hydrophobic and hydrophilic solid surfaces differed at high polymer concentration. Emulsion droplets were found to interact with the hydrophobic interface. Adsorption at silicone oil-water interface resembled adsorption at solid hydrophobic surfaces. Gas was generated through chemical reaction at the interface between two immiscible liquids and the bubbles formation from the generated was studied optically. The gas bubble size was seen to be uninfluenced by the reaction rate. However, bubble formation was seen to take place in one of the phases, held up at the interface before detaching from the interface with a surrounding aqueous film. It was argued that this may affect the final bubble sizes. Slag foaming at high temperatures was studied in laboratory scale with X-ray imaging under dynamic conditions. The foam displayed a fluctuating behaviour, which the presently available models are not able to take into account. The concept of foaming index was found to be unsatisfactory in describing the foaming behaviour under dynamic conditions, thus emphasizing the need for alternative theories. The rate of fluctuations was seen to be related to the difference between rate of gas generation and rate of gas escape from the system (Ug-Ue) as well as the bubble sizes. Thus, it seems like model development of dynamic foaming phenomenon has to take the effective chemical reaction rate as well as the bubble sizes into consideration

Este trabalho apresenta um estudo do efeito do substrato em transistores SOI de camada de silício e óxido enterrado ultrafinos (Ultra Thin Body and Buried Oxide - UTBB). A análise do trabalho foi realizada baseando-se em modelos teóricos, simulações numéricas e medidas experimentais. Experimentalmente pode-se notar que a presença do plano de terra (Ground Plane, GP) abaixo do óxido enterrado elimina e/ou minimiza alguns efeitos indesejados do substrato, tais como a variação do potencial na terceira interface (óxido enterrado/substrato). A densidade de armadilhas de interfaces (Nit) foi um parâmetro importante no ajuste da simulação para se obter curvas de corrente de dreno (IDS) em função da tensão de porta (VGF) e em função da tensão de substrato (VGB) similares às experimentais. As densidades de armadilhas de interface da primeira e da segunda interface foram ajustadas para o valor de 2x1011eV-1cm-2 depois de analisadas as curvas experimentais. Assim, a partir dessas simulações pode-se notar que o modelo usado no simulador era compatível com os resultados experimentais, com erro menor que 10%. Observou-se que o modelo analítico de efeito do substrato proposto por Martino et al. para transistores SOI totalmente depletados com camadas de silício mais espessas (acima de 40 nm) pode ser utilizado para dispositivos UTBB SOI de canal longo (10 m) até a segunda interface (camada de silício/óxido enterrado) entrar em inversão, quando o modelo perde a validade. Utilizando o modelo analítico também foi possível determinar os valores de tensão de substrato máximo (VGBmax) e mínimo (VGBmin), que determinam a tensão que, aplicada no substrato, mudam o estado da terceira interface de inversão para depleção (VGBmin) e de depleção para acumulação (VGBmax). Os valores de VGBmax variaram de 0,57 V à 0,75 V e os de VGBmin de -0,08 V à -3,39 V. O modelo analítico utilizado tem uma concordância ainda maior (menor que 10%) para transistores de canal curto (L=70 nm) em relação ao de canal longo (L=10m), provavelmente devido ao acoplamento eletroestático de fonte/dreno e 6 canal que posterga a formação da camada de inversão da terceira interface, ampliando a faixa de validade do mesmo. Por meio das simulações numéricas também foi possível analisar a concentração de elétrons ao longo do canal do transistor. Observou-se que a condição de polarização da terceira interface (óxido enterrado/substrato) tem grande influência no comportamento da segunda interface (camada de Silício/óxido enterrado) e da primeira (óxido de porta/camada de Silício) nos transistores UTBB SOI. Quando a terceira interface (óxido enterrado/substrato) está em acumulação, a primeira interface possui uma concentração de elétrons menor que a segunda interface, caracterizando assim, uma condução maior pela segunda interface. O simulador também foi utilizado para analisar o potencial interno do transistor ao longo da profundidade. Foram feitas simulações com e sem GP e variando-se a temperatura de operação dos transistores. Foi observado que quanto maior a temperatura de operação, os efeitos do substrato são minimizados devido à diminuição do nível de Fermi. Com a presença do GP a queda de potencial no substrato é praticamente zero enquanto nos dispositivos sem GP variam entre 0,2V e 0,6V. Como nos dispositivos com GP a queda do potencial no substrato é praticamente zero, a queda nos óxidos aumentou em relação aos dispositivos sem GP, podendo causar problemas de confiabilidade. / This work presents a study of the substrate effect on Ultra Thin Body and Buried Oxide (UTBB) SOI transistors. The work analysis was performed based on theoretical models, numerical simulations and experimental measurements. Experimentally, it is possible to notice that the presence of the ground plane implantation (GP) below the buried oxide eliminates and/or minimizes some undesirable effects of the substrate, as the variation of potential drop on third interface (buried oxide/substrate). The interface trap density (Nit) was an important parameter on simulation adjustment to obtain drain current curves as function of front gate bias and back gate bias close to the experimental. The interface trap density of the front and back interface were adjusted to the value of 2x10¹¹ e V-1 cm-2 after the experimental curves were analyzed. So from these simulations, it can be verified that the model used in the simulator was compatible with the experimental results, with error < 10%. It is noted that the analytic model proposed by Martino et al. to analyze the substrate effect for fully depleted SOI transistor with thicker silicon thickness (above 40 nm) is useful for UTBB SOI devices with long channel (L=10 m) until the back interface reach the inversion, when the model is no longer valid. Using the analytic model, it was also possible to determine the values of VGBmax and VGBmin, which represents the back voltage required to change de third interface from inversion to depletion mode (VGBmin), and the depletion to accumulation mode (VGBmax). The value of VGBmax ranged from 0,57 V to 0,75 V and for VGBmin ranged from -0,08 V to -3,39 V. The analytic model has more agreement for short channel (L = 70nm) transistor than the longer one (L = 10m), probably due to the electrostatic coupling between de drain/source and the channel that delays the formation of inversion channel on third interface extending the validity range of the model. By the numerical simulation, it was possible to analyze the electron concentration along the transistor. It was observed that the mode of the third 8 interface influences directly the condition of the back and front interfaces on UTBB SOI transistor. When the third interface is in accumulation mode, the front interface has an electron concentration lower than the back interface, so the current flows mainly on the back interface. This makes the value of the front threshold voltage is less than the analytic model, once the model is valid only if while the back interface is on depletion mode. The numerical simulation was also used to analyze the potential drop on SOI transistor. Simulation was performed with and without GP and varying the temperature. It was observed that for higher temperature, the substrate effect was minimized dur to the decrease of the Fermi level towards the mid-band. With GP, the substrate potential drop is almost zero, while on devices without GP it changes from 0,2 V to 0,6 V For devices with GP the potential, as the drop on substrate is almost zero, the potential drop on front and buried oxide increases, which can causes reliability problems.

<p>In the present work studies were performed to provide understanding for further model development of the two-phase phenomena, film formation from o/w emulsions and slag foaming.</p><p>The drying of o/w emulsions of different oil viscosities on hydrophobic and hydrophilic substrates was studied. The hydrophobic substrate was found to destabilise the oil droplets and to result in a different mechanism for forming continuous oil film. Studies of adsorption behaviour of a series of non-ionic diblock copolymers at relevant interfaces showed that the adsorption behaviour at hydrophobic and hydrophilic solid surfaces differed at high polymer concentration. Emulsion droplets were found to interact with the hydrophobic interface. Adsorption at silicone oil-water interface resembled adsorption at solid hydrophobic surfaces.</p><p>Gas was generated through chemical reaction at the interface between two immiscible liquids and the bubbles formation from the generated was studied optically. The gas bubble size was seen to be uninfluenced by the reaction rate. However, bubble formation was seen to take place in one of the phases, held up at the interface before detaching from the interface with a surrounding aqueous film. It was argued that this may affect the final bubble sizes.</p><p>Slag foaming at high temperatures was studied in laboratory scale with X-ray imaging under dynamic conditions. The foam displayed a fluctuating behaviour, which the presently available models are not able to take into account. The concept of foaming index was found to be unsatisfactory in describing the foaming behaviour under dynamic conditions, thus emphasizing the need for alternative theories. The rate of fluctuations was seen to be related to the difference between rate of gas generation and rate of gas escape from the system (U_g-U_e) as well as the bubble sizes. Thus, it seems like model development of dynamic foaming phenomenon has to take the effective chemical reaction rate as well as the bubble sizes into consideration</p>

The use of gold-based nanoparticles and thin films is very promising when it comes to improving several green nanotechnologies. Therefore, in order to further their use in applications such as electrochromic devices, photovoltaics, light-emitting diodes and photocatalysis, the aim of this work was to study the growth of gold-based nanoparticles and thin films. All depositions were made using DC magnetron sputtering, and optical, structural, electrochemical, electrical and photocatalytic studies of the films and particles were performed. The various applications yield a variety of substrate properties, and how these substrate properties affect gold coalescence was studied by depositing gold on glass slides and on SnO2:In, ITO and TiO2 base layers. Temperature also affects the gold coalescence. Therefore, gold was deposited on heated and non-heated substrates, where the latter were also post-heated, with a temperature range between 25ºC and 140ºC in both cases. Various temperatures were also used for manufacturing gold nanoparticles, and their effect as photocatalytic improvers was tested on WO3 films. The optical properties of Au films on glass were determined by ellipsometry in the 0.25 – 2 µm range, and then a spectral density analysis was performed of the effective dielectric permittivity. This work showed that thin gold films are excellent replacements for oxide-based transparent conductors in electrochromic devices. It was also shown that thin homogeneous gold films were better conductors when they were deposited on glass, compared to when they were deposited on oxide base layers, regardless of the optical, electrical and structural properties, or the doping concentration of the base layers. The results also showed that thin gold films were durable at 76ºC, and hence hold for a typical window temperature of ~70ºC. For higher temperatures, gold deposition on heated and non-heated substrates resulted in a distinct difference in growth, and there was also a distinct difference between post-heated gold films produced at 25ºC, compared to when the films were deposited on heated substrates. In the latter case, an island structure was obtained at 140ºC. Spectral density analysis gave spectral densities of similar shape for nanoparticles and continuous gold films, which is useful information for further investigations.

Este trabalho apresenta um estudo do efeito do substrato em transistores SOI de camada de silício e óxido enterrado ultrafinos (Ultra Thin Body and Buried Oxide - UTBB). A análise do trabalho foi realizada baseando-se em modelos teóricos, simulações numéricas e medidas experimentais. Experimentalmente pode-se notar que a presença do plano de terra (Ground Plane, GP) abaixo do óxido enterrado elimina e/ou minimiza alguns efeitos indesejados do substrato, tais como a variação do potencial na terceira interface (óxido enterrado/substrato). A densidade de armadilhas de interfaces (Nit) foi um parâmetro importante no ajuste da simulação para se obter curvas de corrente de dreno (IDS) em função da tensão de porta (VGF) e em função da tensão de substrato (VGB) similares às experimentais. As densidades de armadilhas de interface da primeira e da segunda interface foram ajustadas para o valor de 2x1011eV-1cm-2 depois de analisadas as curvas experimentais. Assim, a partir dessas simulações pode-se notar que o modelo usado no simulador era compatível com os resultados experimentais, com erro menor que 10%. Observou-se que o modelo analítico de efeito do substrato proposto por Martino et al. para transistores SOI totalmente depletados com camadas de silício mais espessas (acima de 40 nm) pode ser utilizado para dispositivos UTBB SOI de canal longo (10 m) até a segunda interface (camada de silício/óxido enterrado) entrar em inversão, quando o modelo perde a validade. Utilizando o modelo analítico também foi possível determinar os valores de tensão de substrato máximo (VGBmax) e mínimo (VGBmin), que determinam a tensão que, aplicada no substrato, mudam o estado da terceira interface de inversão para depleção (VGBmin) e de depleção para acumulação (VGBmax). Os valores de VGBmax variaram de 0,57 V à 0,75 V e os de VGBmin de -0,08 V à -3,39 V. O modelo analítico utilizado tem uma concordância ainda maior (menor que 10%) para transistores de canal curto (L=70 nm) em relação ao de canal longo (L=10m), provavelmente devido ao acoplamento eletroestático de fonte/dreno e 6 canal que posterga a formação da camada de inversão da terceira interface, ampliando a faixa de validade do mesmo. Por meio das simulações numéricas também foi possível analisar a concentração de elétrons ao longo do canal do transistor. Observou-se que a condição de polarização da terceira interface (óxido enterrado/substrato) tem grande influência no comportamento da segunda interface (camada de Silício/óxido enterrado) e da primeira (óxido de porta/camada de Silício) nos transistores UTBB SOI. Quando a terceira interface (óxido enterrado/substrato) está em acumulação, a primeira interface possui uma concentração de elétrons menor que a segunda interface, caracterizando assim, uma condução maior pela segunda interface. O simulador também foi utilizado para analisar o potencial interno do transistor ao longo da profundidade. Foram feitas simulações com e sem GP e variando-se a temperatura de operação dos transistores. Foi observado que quanto maior a temperatura de operação, os efeitos do substrato são minimizados devido à diminuição do nível de Fermi. Com a presença do GP a queda de potencial no substrato é praticamente zero enquanto nos dispositivos sem GP variam entre 0,2V e 0,6V. Como nos dispositivos com GP a queda do potencial no substrato é praticamente zero, a queda nos óxidos aumentou em relação aos dispositivos sem GP, podendo causar problemas de confiabilidade. / This work presents a study of the substrate effect on Ultra Thin Body and Buried Oxide (UTBB) SOI transistors. The work analysis was performed based on theoretical models, numerical simulations and experimental measurements. Experimentally, it is possible to notice that the presence of the ground plane implantation (GP) below the buried oxide eliminates and/or minimizes some undesirable effects of the substrate, as the variation of potential drop on third interface (buried oxide/substrate). The interface trap density (Nit) was an important parameter on simulation adjustment to obtain drain current curves as function of front gate bias and back gate bias close to the experimental. The interface trap density of the front and back interface were adjusted to the value of 2x10¹¹ e V-1 cm-2 after the experimental curves were analyzed. So from these simulations, it can be verified that the model used in the simulator was compatible with the experimental results, with error < 10%. It is noted that the analytic model proposed by Martino et al. to analyze the substrate effect for fully depleted SOI transistor with thicker silicon thickness (above 40 nm) is useful for UTBB SOI devices with long channel (L=10 m) until the back interface reach the inversion, when the model is no longer valid. Using the analytic model, it was also possible to determine the values of VGBmax and VGBmin, which represents the back voltage required to change de third interface from inversion to depletion mode (VGBmin), and the depletion to accumulation mode (VGBmax). The value of VGBmax ranged from 0,57 V to 0,75 V and for VGBmin ranged from -0,08 V to -3,39 V. The analytic model has more agreement for short channel (L = 70nm) transistor than the longer one (L = 10m), probably due to the electrostatic coupling between de drain/source and the channel that delays the formation of inversion channel on third interface extending the validity range of the model. By the numerical simulation, it was possible to analyze the electron concentration along the transistor. It was observed that the mode of the third 8 interface influences directly the condition of the back and front interfaces on UTBB SOI transistor. When the third interface is in accumulation mode, the front interface has an electron concentration lower than the back interface, so the current flows mainly on the back interface. This makes the value of the front threshold voltage is less than the analytic model, once the model is valid only if while the back interface is on depletion mode. The numerical simulation was also used to analyze the potential drop on SOI transistor. Simulation was performed with and without GP and varying the temperature. It was observed that for higher temperature, the substrate effect was minimized dur to the decrease of the Fermi level towards the mid-band. With GP, the substrate potential drop is almost zero, while on devices without GP it changes from 0,2 V to 0,6 V For devices with GP the potential, as the drop on substrate is almost zero, the potential drop on front and buried oxide increases, which can causes reliability problems.

This thesis is concerned with the study of morphology and properties of sub-micron thin Nafion® films. The motivation of the work arises from the need to characterize the 4 -10 nm thin ionomer films in the catalyst layer of polymer electrolyte fuel cell (PEFC). A protocol for the fabrication of self-assembled ultra-thin Nafion® films on planar substrates was successfully developed. Films of thickness ranging 4 nm-300 nm, determined by three different techniques - variable angle spectroscopy ellipsometry (VASE), atomic force microscope (AFM) and x-ray photo-electron spectroscopy (XPS), could be reproducibly generated on SiO2/Si wafer. The 4 nm thin film is one of the thinnest, continuous film of Nafion® ever reported. This is the first time that the structure/properties of such thin Nafion® film have been investigated. An interesting finding is the thickness-dependent structure and property of these films. Films with thickness <55 nm exhibited hydrophilic-free surface but thicker films (>55 nm) had hydrophobic surface. Similarly, sub-55 nm films had a lower and thickness-independent protonic conductivity compared to thicker films that exhibited thickness-dependent conductivity. Anomalously high water uptake (by quartz crystal microbalance) and swelling (by ellipsometry) of sub-55nm films indicate that low conductivity is not due to low water content However, differences in surface morphology were observed by the AFM phase contrast analysis. The lack of ionic domain was also observed in the thinner films (4-30 nm) from the grazing incidence small x-ray scattering (GISAXS) experiments. Thermal annealing over a range of temperature (110-160 oC) revealed a dramatic switching of the film surface from hydrophilic to hydrophobic was observed for sub-55 nm films with lower thickness film requiring higher annealing temperature. Bulk proton conductivity was significantly reduced after annealing for all films. An interesting finding was the regeneration of conductivity after to prolonged liquid water exposure and a corresponding switching back of the surface to hydrophilic. The thickness-dependent structure/property of ultra-thin Nafion® films is attributed to substrate induced confinement effect. Self-assembly of Nafion® on various substrates (SiO2, carbon, Pt and Au) was studied. The ionomer/substrate interaction and resulting film morphology followed a trend with respect to substrate surface energies and Nafion® dispersion compositions. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2013-09-29 12:36:19.05

Since their discovery at the beginning of the 21st century, two-dimensional (2D) materials have emerged as one of the most exciting material groups offering unique properties which promise a plethora of potential applications in nanoelectronics, quantum computing, and surface science. The progress in the study of 2D materials has advanced rapidly stimulated by the ever-growing interest in their behavior and the fact that they are the ideal specimen for transmission electron microscopy (TEM), as their geometry allows to identify every single atom. Their morphology – 2D materials consist of “surface” only – at the same time makes them sensitive to beam damage, since high-energy electrons easily sputter atoms and introduce defects. While this is in general not desirable – as non-destructive imaging is aimed at – it allows to precisely quantify the damage in TEM and even pattern the 2D material with atomic resolution using the electron beam. Alternatively, patterning of 2D materials can be achieved using focused ion irradiation, which makes studying its effect on 2D materials relevant and essential. In this thesis, we theoretically study the effects of electron and ion irradiation on 2D materials, exemplarily on 2D MoS2 . Specifically, we address the combined effect of electronic excitations and direct momentum transfer by high-energy electrons (knock-on damage) in 2D MoS2 using advanced first-principles simulation techniques, such as Ehrenfest dynamics based on time-dependent density functional theory (DFT). Here, we stress the importance of the combined effect of ionization damage and knock-on damage as neither of these alone can account for experimentally-observed defect production below the displacement threshold – the minimum energy required for the displacement of an atom from the pristine system. A mechanism of defect production relying on the localization of the electronic excitation at the emerging vacancy site is presented. The localized excitation eventually leads to a significant drop in the displacement threshold. The combination of electronic excitation and knock-on damage may in addition to beam-induced chemical etching explain the observed sub-threshold damage in low voltage TEM experiments. Apart from non-destructive imaging, electrons may be used to modify the 2D material intentionally. In this light, we consider the electron-beam driven phase transformation in 2D MoS2 , where the semiconducting polymorph transforms into its metallic counterpart. The phase energetics and a possible transformation mechanism under electron irradiation are investigated using DFT based first-principles calculations. The detailed understanding of the interaction of the electron beam with the 2D material promises to improve the patterning resolution enabling circuit design on the nanoscale. Ion irradiation employed in focussed ion beams (FIB), e.g., the helium ion microscope (HIM) constitutes another tool widely used to pattern and even image 2D materials. Ion bombardment experiment usually carried out for the 2D material placed on a substrate are frequently rationalized using simulations for free-standing systems neglecting the effect of the substrate. Combining Monte Carlo with analytical potential molecular dynamics simulations, we demonstrate that the substrate plays a crucial role in damage production under ion irradiation and cannot be neglected. Especially for light ions such as He and Ne, which are usually used in the HIM, the effect of the substrate needs to be considered to account for the increased number of defects and their broadened spatial distribution which limits the patterning resolution for typical HIM energies. / Seit ihrer Entdeckung Anfang des 21. Jahrhunderts haben sich zwei-dimensionale (2D) Materialien zu einer der spannendsten Materialklassen im Forschungsfeld aus Materialwissenschaft, Physik und Chemie entwickelt. Ihre einzigartigen Eigenschaften versprechen eine Vielzahl potentieller Anwendungen in der Nanoelektronik, für Quantencomputer und in der Oberflächenwissenschaft. Beflügelt durch das wachsende Interesse an ihrem Verhalten und der Tatsache, dass sie die idealen Proben für die Transmissions-Elektronen-Mikroskopie (TEM) darstellen – ihre Geometrie erlaubt es, jedes einzelne Atom zu identifizieren – sind die Forschungen an 2D-Materialien rapide vorangeschritten. Ihre Morphologie – 2D-Materialien bestehen nur aus “Oberfläche” – bedingt zugleich ihre Sensitivität bezüglich Strahlschäden. Hochenergetische Elektronen lösen sehr leicht Atome aus dem 2D-Material und induzieren Defekte. Obwohl dies im Allgemeinen unerwünscht ist – Ziel ist eine nicht-destruktive Bildgebung – erlaubt es doch präzise Einblicke in die Schadensentstehung im TEM. Überdies können 2D-Materialien mit Hilfe des Elektronenstrahls mit atomarer Auflösung strukturiert werden. Alternativ kann die Strukturierung des 2D-Materials über fokussierte Ionenstrahlung erfolgen, weshalb es lohnenswert erscheint, auch deren Effekt auf 2D-Materialien zu untersuchen. In dieser Arbeit werden die Effekte von Elektronen- und Ionenstrahlung auf 2D-Materialien aus theoretischer Sicht exemplarisch an 2D-MoS2 untersucht. Besonderes Augenmerk liegt dabei auf dem kombinierten Effekt von elektronischer Anregung und dem direkten Impulsübertrag durch hochenergetische Elektronen (Kollisionsschaden) in 2D-MoS2 , der durch die Anwendung von Ab-Initio-Simulationstechniken wie der Ehrenfest-Molekulardynamik, basierend auf zeitabhängiger Dichtefunktionaltheorie (DFT), studiert wird. Dabei liegt die Betonung auf der Kombination beider Effekte, da weder Ionisierungs- noch Kollisionsschäden allein die experimentell beobachtete Defekterzeugung unterhalb der Displacement Threshold – der notwendigen Mindestenergie, um ein Atom aus dem reinen Material herauszulösen – erklären. Ein möglicher Mechanismus der Defekterzeugung, basierend auf der Lokalisierung der elektronischen Anregung an der entstehenden Vakanzstelle, wird vorgeschlagen. Die lokalisierte Anregung führt dabei schließlich zu einem signifikanten Absinken der Displacement Threshold. Die Kombination von elektronischer Anregung und Kollisionsschaden trägt neben strahlinduzierten chemischen Reaktionen zur Erklärung der beobachteten Schäden unterhalb der Displacement Threshold in Niederspannungs-TEM-Experimenten bei. Neben nicht-destruktiver Bildgebung können Elektronenstrahlen auch dafür benutzt werden, 2D-Materialien gezielt zu modifizieren. In diesem Sinne wird der elektronenstrahl-induzierte Phasenübergang in 2D-MoS2 , bei dem sich das Material von einem halbleitenden in einen metallischen Zustand transformiert, betrachtet. Die Phasenenergetik und ein möglicher Transformationsmechanismus werden unter Zuhilfenahme von DFT-basierten Ab-Initio-Simulationen untersucht. Das detaillierte Verständnis der Interaktion des Elektronenstrahls mit dem 2D-Material verspricht dabei die Strukturierungsauflösung zu verbessern und ermöglicht Schaltkreisdesign auf der Nanoskala. Fokussierte Ionenstrahlen, wie sie in Ionenstrahlinstrumenten – wie dem Helium-Ionen-Mikroskop (HIM) zum Einsatz kommen – stellen ein weiteres häufig verwendetes Werkzeug zur Modifikation sowie zur Bildgebung von 2D-Materialien dar. Ionenstrahlexperimente – üblicherweise mit dem auf einem Substrat platzierten 2D-Material durchgeführt – werden hingegen oft mit Simulationen für freistehende 2D-Materialien rationalisiert, wobei jegliche Einwirkung des Substrats vernachlässigt wird. Die Kombination von Monte-Carlo-Simulationen mit Molekulardynamik-Simulationen (auf der Basis analytischer Potentiale) in dieser Arbeit verdeutlicht, dass das Substrat eine wichtige Rolle in der Defekterzeugung spielt und nicht vernachlässigt werden kann. Besonders für leichte Ionen, wie He und Ne, wie sie typischerweise im HIM zum Einsatz kommen, sollte der Effekt des Substrats berücksichtigt werden. Dieses führt für typische Ionenenergien im HIM – im Vergleich zum freistehenden 2D-Material – zu einer ansteigenden Anzahl an Defekten und einer breiteren räumlichen Defektverteilung, welche die Strukturierungsauflösung begrenzt.

Les propriétés optiques et vibrationnelles de nanoparticules métalliques individuelles ont été étudiées par spectroscopie par modulation spatiale (SMS), avec une attention particulière aux effets de forme, composition, environnement local, ainsi que de couplage inter-particule. La réponse optique de nanoparticules (métalliques au cœur-couronne métal-diélectrique) allongées et des particules bimétalliques (hétérodimères or-argent) a été mesuré et en suite interprétée grâce à une corrélation avec la caractérisation morphologique de la même particule obtenue par microscopie à transmission électronique et avec des simulations par éléments finis prenants en compte la réelle géométrie du nano-objet et le substrat. Une technique pompe sonde résolue en temps a été en suite utilisée pour étudier le profil Fano dans l'absorption d'une particule d'or au sein d'un hétérodimères or-argent. Sur une échelle de temps des quelques dizaines de picosecondes, les vibrations acoustiques multimodales de nanobipyramides d'or individuelles ont été optiquement détectées et caractérisées par rapport à un modèle élastique classique / Optical and vibrational properties of individual metal-based nanoparticles have been investigated by spatial modulation spectroscopy (SMS), focusing on their dependence on nano-object shape, composition, environment and inter-particle coupling. Quantitative investigations of the optical response, and in particular, the surface plasmon resonance (extinction cross-section amplitude, spectral position and linewidth) of elongated metal or metal-dielectric (gold nanorods, nanobipyramids with or without silica coating) and bimetallic (gold-silver heterodimers) nanoparticles deposited on a substrate have first been performed. The same nanoparticles were characterized by electron microscopy permitting quantitative interpretation of their optical response using finite element numerical simulations, taking into account the influence of the substrate. Combining SMS microscopy with a high sensitivity femtosecond two-color pump-probe setup, the ultrafast dynamics of single nano-objects has been investigated. The Fano absorption profile of a gold nanoparticle within a single gold-silver heterodimer, a parameter not accessible by linear spectroscopy, was directly measured. On a picosecond time-scale, multimodal acoustic vibrations of single gold nanobipyramids were optically lunched and detected, and their features compared to a model based on continuum elasticity