Nanoporous low-k dielectrics are used for integrated circuit interconnects to reduce the propagation delays, and cross talk noise between metal wires as an alternative material for SiO2. These materials, typically organosilicate glass (OSG) films, are exposed to oxygen plasmas during photoresist stripping and related processes which substantially damage the film by abstracting carbon, incorporating O and OH, eventually leading to significantly increased k values. Systematic studies have been performed to understand the oxygen plasma-induced damage mechanisms on different low-k OSG films of various porosity and pore interconnectedness. Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and atomic force microscopy are used to understand the damage kinetics of O radicals, ultraviolet photons and charged species, and possible ways to control the carbon loss from the film. FTIR results demonstrate that O radical present in the plasma is primarily responsible for carbon abstraction and this is governed by diffusion mechanism involving interconnected film nanopores. The loss of carbon from the film can be controlled by closing the pore interconnections, He plasma pretreatment is an effective way to control the damage at longer exposure by closing the connections between the pores.

This cumulative dissertation is a compilation of eight peer-reviewed, published scientific papers on the subject of two microscopic techniques of diffusion measurement, namely infrared (IR) microimaging and pulsed field gradient (PFG) NMR. The dissertation contains mainly five chapters. The first chapter introduces diffusion phenomena in general and concisely explains the importance and the current challenges of the investigation of molecular diffusion in nanoporous materials, which are the primary motivations behind the present work. To rise the challenges, it proposes an option of employing IR microimaging in parallel with PFG NMR in the measurement of the molecular diffusion. The second chapter describes the basic principles of the two diffusion measurement techniques and what they are capable of. Chapters 3 and 4 deliver convincing demonstrations of their applicability and potential in diffusion studies. Lastly, Chapter 5 concludes the present work by discussing complementary benefits of the two techniques, along with the novel application of the two-region model for assessing mass transfer in hierarchically porous materials.:Table of Contents CHAPTER 1. Introduction CHAPTER 2. Basics of diffusion measurement techniques 2.1. Introduction to infrared microscopy (IRM) 2.1.1. Working principle 2.1.2. Experimental setup 2.2. Introduction to pulsed field gradient nuclear magnetic resonance (PFG NMR) 2.2.1. Self-diffusion and propagator 2.2.2. Theory of PFG NMR CHAPTER 3. Applicability and potential of IRM • Publication 3.1. Anomaly in the chain length dependence of n-alkane diffusion in ZIF 4 metal-organic frameworks • Publication 3.2. Metal-organic framework Co-MOF-74-based host-guest composites for resistive gas sensing • Publication 3.3. Revealing the transient concentration of CO2 in a mixed-matrix membrane by IR microimaging and molecular modeling • Publication 3.4. IR microimaging of direction-dependent uptake in MFI-type crystals CHAPTER 4. Importance of PFG NMR in diffusion studies • Publication 4.1. NMR diffusometry with guest molecules in nanoporous materials • Publication 4.2. Structural characterisation of hierarchically porous silica monolith by NMR cryo-porometry and -diffusometry CHAPTER 5. Complementary benefits of IR microimaging and PFG NMR • Publication 5.1. Diffusion in nanopores: correlating experimental findings with 'first-principles' predictions • Publication 5.2. Diffusion analysis in pore hierarchies by the two-region model Bibliography Appendix A. Supporting information Appendix B. Author contributions

Aligned arrays of nanostructures has recently attracted great interest because of their unique properties and potential use in a broad range of technological applications. The nanostructures can be employed when it is essential to create large surface on a small area in electronic device as sensor technology or energetics e.g. solar panels. One of the simplest and low-cost methods of fabricating nanostructures is template-assisted electrochemical deposition. This method also enables good control over the nanostructure dimensions and can be used to deposit a wide range of materials. The proposed method consists of two steps. At first, a non-conductive nanoporous template has to be created and then nanostructures are formed by electrodeposition into the template which is coated with a metal on one of its sides or placed on a metal surface.

The controlled assembly of molecular building blocks is an emerging strategy that allows for the preparation of materials with tailor-made properties. This involves the precise combination of molecular subunits that interact with one another via specifically designed reactive sites. Such a strategy has produced materials exhibiting remarkable properties, including those based on metal-organic frameworks and single-molecule magnets. The present Thesis aims to highlight how such metal-organic assemblies can be engineered at the molecular level to promote certain desired functionalities. Specifically, Chapter 2 will focus on the confinement effects of a crystalline sponge on a ferrocene-based guest molecule that is nanostructured within the porous cavities of a host material. In doing so, we evaluate how one can exert some level of control over the binding sites of the guest molecule, through the addition of electron-withdrawing groups, as well as tuning the physical properties of the guest itself through molecular encapsulation. Notably, we demonstrate a distinct change in the dynamic rotational motion of the ferrocene molecules once confined within the crystalline sponge. In Chapter 3, we investigate the generation of slow relaxation of the magnetization from a Co(II)-based metal-organic framework. We compare this to a closely related 2D Co(II) sheet network, and how slight changes in the crystal field, probed through computational methods, can impact the magnetic behaviour. This type of study may be particularly beneficial in the optimization of single-ion magnets, by sequestering metal centres in select chemical environments, and minimizing molecular vibrations that may offer alternative magnetic relaxation pathways. We extend these principles in Chapter 4, through the use of a nitrogen-rich ligand that acts as a scaffold for Ln(III) ions, thereby yielding 0D and 1D architectures. The coordination chemistry of Ln(III) ions with N-donor ligands remains scarce, especially when evaluated from a magnetic perspective, and therefore, we sought to determine the magnetic behaviour of such compounds. The monomeric unit displays clear single-molecule magnet behaviour with an energetic barrier for the reversal of the magnetization, while the 1D chain displays weaker magnetic characteristics. Nevertheless, such compounds incorporating nitrogen-rich ligands offer much promise in the design of environmentally-friendly energetic materials. In Chapter 5, we take a look at different two different systems that involve the formation of radical species. On one hand, we can promote enhanced magnetic communication between Ln(III) ions, which is typically quite challenging to achieve given the buried nature of the 4f orbitals, and on the other hand, we rely on a redox-active ligand to design stimuli-responsive metal-organic assemblies. The latter case provides access to “smart” molecular materials that can respond to changes in their environment. Here, a multi-stimuli responsive nanobarrel was studied, which displayed sensitivity to ultraviolet radiation, heat and chemical reduction. Lastly, Chapter 6 provides a new method for the systematic generation of cationic frameworks, termed Asymmetric Ligand Exchange (ALE). This strategy focuses on the replacement of linear dicarboxylates with asymmetric linkers that features one less negative charge, in order to tune the ionicity of porous frameworks. This allows for the retention of the structural topology and chemical reactivity of the original framework, representing distinct advantages over other similar strategies. Methods to retain permanent porosity in such cationic frameworks are also proposed. Altogether, these studies highlight how the directed assembly of ordered networks can generate varied properties of high scientific interest.

Les enjeux de réduction des consommations des transports amplifie l'intérêt pour de nouveaux stockages d'énergie a forte densité de puissance et d'amortisseurs performants permettant d'alléger les structures. Les systèmes Hétérogènes Lyophobes (SHL) utilisent le mouillage forcé de matrices poreuses pour convertir les énergies mécaniques en énergies interfaciales qui peuvent ensuite être restituée(stockage) ou dissipée(amortisseur) selon le choix de liquide et de matériau. Ces systèmes ont été étudiés depuis les années 80 du fait de leurs propriétés prometteuses pour ces applications en amortissement et stockage d'énergie mécaniques mais aussi comme objet physique.L'application de ces systèmes requière de comprendre leurs intrusion et extrusion du liquide hors du volume poreux sur une plage de température et de durée d'intrusion.Un dispositif d'intrusion à haute pression (100 MPa) a été développé pour étudier l'impact de la température (5-70°C) et de la durée d'intrusion sur trois décades afin de mesurer précisément le comportement dynamique à échelle macroscopique.Ce dispositif a été utilisé pour étudier un matériau de porosité cylindrique (MCM-41) qui a été rendu non mouillant par un greffage hydrophobe en condition anhydre stricte qui a été intégré au laboratoire.Les pressions d'intrusions de l'eau dans le MCM-41 sur une large plage de durée et de température ont confirmé le modèle d'ancrage de la ligne de contact au cours de l'intrusion et à l'extrusion le modèle de nucléation de bulle avec la contribution majeure de la tension de ligne, mesurée sur les autres solutions aqueuses. Des mesures inédites avec de l'eau deutérée, des solutions salines jusqu'à saturation et en pH alcalin ont éclairé la contribution des liaisons hydrogènes, des ions et des silanols sur la pression d'intrusion et la dissipation d'énergie.Le deuxième matériau étudié (ZIF-8) présente une structure cristalline de cages nanométriques connectées par des ouvertures commensurables avec les molécules d'eau dont l'intrusion présente une hystérèse réduite pour le stockage d'énergie. Les mesures dynamiques précises ont montré au-dessus de 35°C un comportement inédit de constance de la pression d'intrusion sur trois décades de durée. Aux températures inférieures une surpression de grande ampleur en puissance -1/2 contraste avec les modèles de réponse linéaire et présente une dépendance affine en température.Des mesures dynamiques inédites avec de l'eau deutérée ont révélé un impact significatif des liaisons hydrogènes. Des particules de différentes durée de synthèse ont montré que la pression d'intrusion est principalement pilotée par des défauts et non la capillarité.Ces résultats inédits ont amené à réaliser des expériences de diffusion de neutrons sous pression qui ont apporté des mesures inédites de déformation des pores cylindriques sous l'effet de l'intrusion et confirmé l'existence de cluster d'eau séparé au sein du ZIF-8. / The stakes of reducing the consumption of transportation drives the interest in high density energy storage as well as shock absorbers to reduce the weight and power of vehicles.Heterogeneous Lyophobic Systems leverage forced wetting to convert mechanical energy into interfacial energy which can be recovered later (storage) or dissipated (damper) depending on the choice of liquid and material.These systems have been studied since the 80s because of their promising properties for damping and storage applications but also as a physics topic.Actual use of these systems require the understanding and control of their intrusion and extrusion pressures in a relevant range of temperatures and over different time scales.A macroscopic high pressure intrusion device (100 MPa) was developed to study the impact of temperature (5-70°C) and the duration of intrusion over three decades to measure precisely the dynamic behavior.This device was used to study a material with cylindrical pores (MCM-41) which was made non-wetting thank to anhydrous hydrophobic grafting protocol that has beenintegrated into the laboratory.Water intrusion pressures in the MCM-41 over a wide rangeof time and temperature confirmed the model of anchored contact line duringintrusion and the bubble nucleation model during extrusion.This confirmed the key contribution of line tension which was quantified and in water and on other aqueous solutions.Original measures with deuterated water, saturated brine andhigh pH have clarified the contributions from hydrogen bonds, ions and silanols to the intrusion pressure and energy dissipation.The second material (ZIF-8) is a crystal composed of nanometric cavities connected by openings as large as water molecules. Water intrusion has a low hysteresis suitable for storage and above 35°C a unprecedented behavior of constant pressure of intrusion spanning three orders of intrusion duration.At lower temperatures, intrusion pressures see ample increase scaling as a power law -1/2 which conflicts with linear response behavior. This descriptive model depends linearly on temperature, dropping to zero at 35°C.First measurements on deuterated water showed similar pattern and a strong impact of hydrogen bonds. Particles from different synthesis durations showed that the intrusion pressure is heavily dependent on inner defects and not capillarity.Those new results driving questions about microscopic mechanisms lead to neutron scattering experiments under pressure. These brought unprecedented measures of cylindrical pores deformations under intrusion and confirmed the division of water in ZIF-8 cavities.

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The main objective of this doctoral thesis is explore the origin of the nanoporous carbons photoactivity for studying their applications in different fields of research covering their use as photocatalysts for pollutants degradation as well as photoelectrodes for water photooxidation reaction, either by themselves or as additives coupled to a semiconductor in hybrid electrodes. The first stage of this study mainly consisted in investigating the photoactivity of carbon materials by themselves (in the absence of semiconductors) towards different reactions, aiming at linking their photochemical response with the carbon material nature in terms of porosity, surface chemistry, composition and structure. The exploration of the photoassisted degradation of phenol nanoconfined in the pore voids of several nanoporous carbons showed a positive effect of the tight packing of the molecule in the carbon material porosity. This indicated the role of confinement to boost fast interactions between the photogenerated charge carriers at carbon material surface and the molecule adsorbed inside pores. The irradiation wavelength was found as a key variable upon phenol photooxidation reaction, with the best optimum performance at low and high wavelengths, and a minimum photodegradation yield at ca. 400 nm for all tested carbon materials. Another parameter strongly influencing the photoactivity of the nanoporous carbons was the surface functionalisation. When sulphur was incorporated to a carbon matrix, the light conversion towards the phenol photooxidation became more efficient and it was dependent on the nature of the S-containing groups. Further on, the analysis of photocurrent transients obtained by irradiating several nanoporous carbon electrodes exhibited different responses, with either anodic or cathodic photocurrent, and transient shapes, thus demonstrating the distinct nature of the catalysed reaction occurring onto electrode/electrolyte interface. The second stage deals with hybrid nanoporous carbon/semiconductor (i.e. WO3) electrodes which allowed to explore the role of nanoporous carbon as additive towards water oxidation reaction. The presence of carbon material had a notable effect on the hybrid electrode performance, in terms of conversion efficiency (IPCE), likely due to the improved collection of the photogenerated electrons by carbon matrix. An optimal amount of carbon additive of ca. 20 wt.% was obtained for the best performing hybrid electrode, with a twofold IPCE compared to that obtained for bare WO3 electrode. The effect of carbon matrix on WO3 performance was found dependent on semiconductor crystalline structure.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第21881号 / エネ博第382号 / 新制||エネ||74(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー応用科学専攻 / (主査)教授 馬渕 守, 教授 宅田 裕彦, 教授 土井 俊哉 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

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