Le moment angulaire est une quantité essentielle pour l'étude d'objets en interaction. Tout comme la matière, un rayonnement porte du moment angulaire. Il se décompose en deux composantes, moment angulaire de spin (MAS) et moment angulaire orbital (MAO). Chacune de ces composantes a des propriétés spécifiques et ont donné lieu à de nombreuses applications en utilisant de la lumière dans le domaine visible et infrarouge. Dans cette thèse, nous nous proposons d'étudier le comportement des deux types de moment angulaire de la lumière dans un processus très non-linéaire appelé génération d'harmoniques d'ordre élevé (GHOE). Dans ce processus physique connu depuis 1987, un laser infrarouge intense est focalisé dans un jet d'atomes ou de molécules, ce qui dans le bon régime d'intensité permet de générer un rayonnement à courte longueur d'onde (domaine extrême ultraviolet) et extrêmement bref (attoseconde, 1 as = 10⁻¹⁸ s). Nous commençons par décrire théoriquement ce processus, ainsi que définir de manière approfondie la notion de moment angulaire de la lumière. Nous étudions ensuite la GHOE à partir d'un faisceau infrarouge portant du MAO, ce qui nous permet d'obtenir une source unique, générant des impulsions lumineuses ultrabrève de moment angulaire orbital contrôlé et de longueur d'onde de l'ordre de 10nm. Nous étudions étudions la GHOE à partir de faisceaux portant du MAS. En utilisant une résonance du gaz de génération, nous parvenons à transmettre ce moment angulaire au rayonnement extrême ultraviolet. Ce rayonnement est ensuite utilisé pour mesurer des dichroïsmes circulaires de photoionisation dans des molécules chirales, mesures auparavant réservées aux sources synchrotrons. Ceci ouvre la voie à des mesures chirotpiques résolues en temps à l'échelle femto/attoseconde. / Angular momentum is an ubiquitous quantity in all areas of physics. Just like matter, radiation carries angular momentum. It can be decomposed in two parts, namely the spin angular momentum (SAM) and the orbital angular momentum (OAM). Each one of these components has very specific properties and lead to numerous applications using visible and infrared light. In this thesis, we study the behavior of these two types of light angular momentum in a very non-linear process called high harmonic generation (HHG). In this physical process known since 1987, an intense infrared laser is focused into an atomic or molecular gas jet, which in the right intensity regime allows to generate a radiation which has a short wavelength (extreme ultraviolet domain) and is extremely brief (attosecond, 1 as = 10⁻¹⁸ s).We begin by describing theoretically this process, as well as defining in depth the notion of light angular momentum. We then study HHG from an infrared laser carrying OAM. This allows to obtain an unique light source, generating ultrashort light pulses of controlled orbital angular momentum with a wavelength of the order of 10 nm. We then study GHOE from beams carrying MAS. Using a resonance from the generation gas, we manage to transfer this angular momentum to the emitted extreme ultraviolet radiation. This radiation is finally used to measure photoionisation circular dichroisms in chiral molecules, measurements previously restricted to synchrotron sources. This paves the way towards chiroptic time resolved measurement on a femto/attosecond timescale.

A dexametasona (DEX) está entre os glicocorticóides mais comumente descritos para uso sistêmico apresentando uma atividade gliconeogênica, imunossupressora e antiinflamatória bem difundida. Apresenta, em sua estrutura, sítios com potencial capacidade de interação com outras moléculas. Alguns ácidos carboxílicos aromáticos (ACA) e seus derivados são utilizados como excipientes em formulações farmacêuticas e também possuem grupos funcionais com propriedades potenciais de interação. Esta associação aparece, portanto, como um bom modelo de estudo para a compreensão de interações em estado sólido. Este trabalho foi desenvolvido para verificar a existência de interações, no estado sólido, da DEX com os ACA: benzóico, salicílico, 4-hidróxi-benzóico, 2,4-diidróxi-benzóico, 2,3,4-triidróxi-benzóico, gálico, 3-hidróxi-fenilacético, 3,4-diidróxi-fenilacético e isoftálico. A fim de elucidar o comportamento destes sólidos em misturas físicas binárias equiponderais foram empregadas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho e difratometria de raios-X. A dexametasona (DEX) está entre os glicocorticóides mais comumente descritos para uso sistêmico apresentando uma atividade gliconeogênica, imunossupressora e antiinflamatória bem difundida. Apresenta, em sua estrutura, sítios com potencial capacidade de interação com outras moléculas. Alguns ácidos carboxílicos aromáticos (ACA) e seus derivados são utilizados como excipientes em formulações farmacêuticas e também possuem grupos funcionais com propriedades potenciais de interação. Esta associação aparece, portanto, como um bom modelo de estudo para a compreensão de interações em estado sólido. Este trabalho foi desenvolvido para verificar a existência de interações, no estado sólido, da DEX com os ACA: benzóico, salicílico, 4-hidróxi-benzóico, 2,4-diidróxi-benzóico, 2,3,4-triidróxi-benzóico, gálico, 3-hidróxi-fenilacético, 3,4-diidróxi-fenilacético e isoftálico. A fim de elucidar o comportamento destes sólidos em misturas físicas binárias equiponderais foram empregadas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho e difratometria de raios-X. / Dexamethasone is one of the most prescribed glucocorticoid drugs for systemic use with gluconeogenic, immunosuppressive and anti-inflammatory properties. Its molecule shows some interesting reactive sites, which can undergo physical associations with other substances. Aromatic carboxylic acid or derivatives are employed as excipients in pharmaceutical formulations and due to the presence of functional groups with potential interaction ability they can be considered so much as DEX as suitable models for a better understanding of interaction phenomena in binary mixtures in solid state. Following aromatic carboxylic acids were investigated: benzoic, salicylic, 4-hydroxybenzoic, 2,4-dihydroxybenzoic, 2,3,4-trihydroxybenzoic, gallic, 3-hydroxyphenylacetic, 3,4-dihydroxyphenylacetic and isophthalic. The occurrence of interaction was analyzed by differential scanning calorimetry (DSC), infrared spectroscopic and X-ray diffractometric techniques in order to elucidate the behavior of equiponderal binary physical mixtures. The characterization of the interactions was also performed by using molecular modeling tools. The results showed the interaction between the ACA and the DEX. Interaction potential was related neither to the number nor to the position of the hydroxyl groups in the aromatic ring of the ACA. Correlation analysis of the ACA’s theoretic pka and log P with thermal parameters were employed to explain the contribution of the molecules and some elected sites in the referred interactions. The relationship with Log P was satisfactory being its correlation coefficient equal to 0.71. The interactions induced an improvement of DEX hydrosolubility supporting the results originated from the solid state analyses, which suggested the occurrence of hydrogen bonds between dexamethasone and the evaluated ACA.

A dexametasona (DEX) está entre os glicocorticóides mais comumente descritos para uso sistêmico apresentando uma atividade gliconeogênica, imunossupressora e antiinflamatória bem difundida. Apresenta, em sua estrutura, sítios com potencial capacidade de interação com outras moléculas. Alguns ácidos carboxílicos aromáticos (ACA) e seus derivados são utilizados como excipientes em formulações farmacêuticas e também possuem grupos funcionais com propriedades potenciais de interação. Esta associação aparece, portanto, como um bom modelo de estudo para a compreensão de interações em estado sólido. Este trabalho foi desenvolvido para verificar a existência de interações, no estado sólido, da DEX com os ACA: benzóico, salicílico, 4-hidróxi-benzóico, 2,4-diidróxi-benzóico, 2,3,4-triidróxi-benzóico, gálico, 3-hidróxi-fenilacético, 3,4-diidróxi-fenilacético e isoftálico. A fim de elucidar o comportamento destes sólidos em misturas físicas binárias equiponderais foram empregadas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho e difratometria de raios-X. A dexametasona (DEX) está entre os glicocorticóides mais comumente descritos para uso sistêmico apresentando uma atividade gliconeogênica, imunossupressora e antiinflamatória bem difundida. Apresenta, em sua estrutura, sítios com potencial capacidade de interação com outras moléculas. Alguns ácidos carboxílicos aromáticos (ACA) e seus derivados são utilizados como excipientes em formulações farmacêuticas e também possuem grupos funcionais com propriedades potenciais de interação. Esta associação aparece, portanto, como um bom modelo de estudo para a compreensão de interações em estado sólido. Este trabalho foi desenvolvido para verificar a existência de interações, no estado sólido, da DEX com os ACA: benzóico, salicílico, 4-hidróxi-benzóico, 2,4-diidróxi-benzóico, 2,3,4-triidróxi-benzóico, gálico, 3-hidróxi-fenilacético, 3,4-diidróxi-fenilacético e isoftálico. A fim de elucidar o comportamento destes sólidos em misturas físicas binárias equiponderais foram empregadas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho e difratometria de raios-X. / Dexamethasone is one of the most prescribed glucocorticoid drugs for systemic use with gluconeogenic, immunosuppressive and anti-inflammatory properties. Its molecule shows some interesting reactive sites, which can undergo physical associations with other substances. Aromatic carboxylic acid or derivatives are employed as excipients in pharmaceutical formulations and due to the presence of functional groups with potential interaction ability they can be considered so much as DEX as suitable models for a better understanding of interaction phenomena in binary mixtures in solid state. Following aromatic carboxylic acids were investigated: benzoic, salicylic, 4-hydroxybenzoic, 2,4-dihydroxybenzoic, 2,3,4-trihydroxybenzoic, gallic, 3-hydroxyphenylacetic, 3,4-dihydroxyphenylacetic and isophthalic. The occurrence of interaction was analyzed by differential scanning calorimetry (DSC), infrared spectroscopic and X-ray diffractometric techniques in order to elucidate the behavior of equiponderal binary physical mixtures. The characterization of the interactions was also performed by using molecular modeling tools. The results showed the interaction between the ACA and the DEX. Interaction potential was related neither to the number nor to the position of the hydroxyl groups in the aromatic ring of the ACA. Correlation analysis of the ACA’s theoretic pka and log P with thermal parameters were employed to explain the contribution of the molecules and some elected sites in the referred interactions. The relationship with Log P was satisfactory being its correlation coefficient equal to 0.71. The interactions induced an improvement of DEX hydrosolubility supporting the results originated from the solid state analyses, which suggested the occurrence of hydrogen bonds between dexamethasone and the evaluated ACA.

A dexametasona (DEX) está entre os glicocorticóides mais comumente descritos para uso sistêmico apresentando uma atividade gliconeogênica, imunossupressora e antiinflamatória bem difundida. Apresenta, em sua estrutura, sítios com potencial capacidade de interação com outras moléculas. Alguns ácidos carboxílicos aromáticos (ACA) e seus derivados são utilizados como excipientes em formulações farmacêuticas e também possuem grupos funcionais com propriedades potenciais de interação. Esta associação aparece, portanto, como um bom modelo de estudo para a compreensão de interações em estado sólido. Este trabalho foi desenvolvido para verificar a existência de interações, no estado sólido, da DEX com os ACA: benzóico, salicílico, 4-hidróxi-benzóico, 2,4-diidróxi-benzóico, 2,3,4-triidróxi-benzóico, gálico, 3-hidróxi-fenilacético, 3,4-diidróxi-fenilacético e isoftálico. A fim de elucidar o comportamento destes sólidos em misturas físicas binárias equiponderais foram empregadas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho e difratometria de raios-X. A dexametasona (DEX) está entre os glicocorticóides mais comumente descritos para uso sistêmico apresentando uma atividade gliconeogênica, imunossupressora e antiinflamatória bem difundida. Apresenta, em sua estrutura, sítios com potencial capacidade de interação com outras moléculas. Alguns ácidos carboxílicos aromáticos (ACA) e seus derivados são utilizados como excipientes em formulações farmacêuticas e também possuem grupos funcionais com propriedades potenciais de interação. Esta associação aparece, portanto, como um bom modelo de estudo para a compreensão de interações em estado sólido. Este trabalho foi desenvolvido para verificar a existência de interações, no estado sólido, da DEX com os ACA: benzóico, salicílico, 4-hidróxi-benzóico, 2,4-diidróxi-benzóico, 2,3,4-triidróxi-benzóico, gálico, 3-hidróxi-fenilacético, 3,4-diidróxi-fenilacético e isoftálico. A fim de elucidar o comportamento destes sólidos em misturas físicas binárias equiponderais foram empregadas técnicas de calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho e difratometria de raios-X. / Dexamethasone is one of the most prescribed glucocorticoid drugs for systemic use with gluconeogenic, immunosuppressive and anti-inflammatory properties. Its molecule shows some interesting reactive sites, which can undergo physical associations with other substances. Aromatic carboxylic acid or derivatives are employed as excipients in pharmaceutical formulations and due to the presence of functional groups with potential interaction ability they can be considered so much as DEX as suitable models for a better understanding of interaction phenomena in binary mixtures in solid state. Following aromatic carboxylic acids were investigated: benzoic, salicylic, 4-hydroxybenzoic, 2,4-dihydroxybenzoic, 2,3,4-trihydroxybenzoic, gallic, 3-hydroxyphenylacetic, 3,4-dihydroxyphenylacetic and isophthalic. The occurrence of interaction was analyzed by differential scanning calorimetry (DSC), infrared spectroscopic and X-ray diffractometric techniques in order to elucidate the behavior of equiponderal binary physical mixtures. The characterization of the interactions was also performed by using molecular modeling tools. The results showed the interaction between the ACA and the DEX. Interaction potential was related neither to the number nor to the position of the hydroxyl groups in the aromatic ring of the ACA. Correlation analysis of the ACA’s theoretic pka and log P with thermal parameters were employed to explain the contribution of the molecules and some elected sites in the referred interactions. The relationship with Log P was satisfactory being its correlation coefficient equal to 0.71. The interactions induced an improvement of DEX hydrosolubility supporting the results originated from the solid state analyses, which suggested the occurrence of hydrogen bonds between dexamethasone and the evaluated ACA.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-09T11:58:12Z No. of bitstreams: 1 adriananascimentodesouza.pdf: 1757133 bytes, checksum: 69514ee02274bd2e690a0252c528c6f5 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-26T20:25:02Z (GMT) No. of bitstreams: 1 adriananascimentodesouza.pdf: 1757133 bytes, checksum: 69514ee02274bd2e690a0252c528c6f5 (MD5) / Made available in DSpace on 2017-06-26T20:25:02Z (GMT). No. of bitstreams: 1 adriananascimentodesouza.pdf: 1757133 bytes, checksum: 69514ee02274bd2e690a0252c528c6f5 (MD5) Previous issue date: 2015-10-01 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho teve como objetivo a produção de uma cápsula selada de ²²Na, funcionando como fonte emissora de pósitrons, para a nova linha de pesquisa do Laboratório de Espectroscopia Atômica e Molecular (LEAM) da UFJF, que visa a aplicação de feixes de pósitrons lentos, ao invés de elétrons nos aparelhos disponíveis no LEAM, no estudo de átomos ou moléculas. O trabalho englobou várias etapas, tais como a escolha da fonte emissora de pósitrons, o armazenamento do radionuclídeo, o projeto da cápsula selada, sua construção, o desenvolvimento de um sistema de carregamento da cápsula, sua selagem, considerando todos os aspectos inerentes à proteção radiológica. A fonte emissora de pósitron escolhida foi o elemento radioativo 22Na, radioisótopo de meia vida longa (2,6 anos) e meia vida biológica (11 dias) razoavelmente baixa. Sua aplicação não é imediata e requer seu acondicionamento adequado e seguro em uma cápsula perfeitamente selada, sendo posteriormente, necessário moderar a energia dos pósitrons rápidos emitidos espontaneamente pela fonte. Esta é a primeira cápsula de 22Na selada produzida no Brasil, colocando-nos no seleto grupo de pesquisadores que dominam esta tecnologia. / This work aimed to produce a sealed capsule of ²²Na, consisting of a source of positrons for the new line of research of Atomic and Molecular Spectroscopy Laboratory (LEAM) - UFJF, to use optionally slow positron beams, rather than electrons, in the apparatus available in this laboratory to study atoms and molecules. The work encompassed several steps, such as the choice of the emission source of positrons, radionuclide storage, the sealed capsule design, its construction, the development of a charging system of the capsule, sealing, considering all aspects of inherent in radiological protection. The positron source chosen was the radioactive element ²²Na, long half-life radioisotope (2.6 years) and reasonably low biological half-life (11 days). Its application is not immediate and requires its proper and safe packaging in a perfectly sealed capsule, being subsequently necessary to moderate the energy of fast positrons spontaneously emitted by the source. This is the first ²²Na sealed capsule produced in Brazil, placing us in the select group of researchers who have mastered this technology.

No description available.

Les mono-couches auto-assemblées (SAMs) sont des systèmes de choix pour le développement de plateformes moléculaires aux propriétés physico-chimiques contrôlées. Il s’agit de monocouches organisées de molécules bi-fonctionnelles. Ces molécules se composent d’une fonction terminale modulable, séparée d’un groupement d’ancrage par un espaceur adapté. Ainsi, les propriétés des SAMs peuvent être ajustées pour le développement de systèmes électroniques moléculaires ou de capteurs (bio)-chimiques. De plus, des structurations chimiques supplémentaires peuvent être induites par irradiation.Les méthodes d’irradiation les plus courantes impliquent des particules de haute énergie. Les dommages induits résultent de plusieurs mécanismes en compétition (ionisations, excitations, dissociations). Dans cette thèse, les électrons lents (0-20 eV) sont utilisés comme particules primaires, et les processus d’interaction électron-SAM sont étudiés afin d’identifier les résonances d’attachement électronique. Aux énergies concernées, des processus dissociatifs sélectifs et efficaces peuvent être mis à profit pour proposer des stratégies d’irradiation menant à des modifications chimiques contrôlées et optimisées.Des SAMs modèles de thiols sur or sont étudiées par une technique de spectroscopie vibrationnelle de forte sensibilité de surface, la spectroscopie de perte d’énergie d’électrons lents (HREELS). Elle permet à la fois de caractériser les SAMs et de sonder les processus d'interaction électron-molécule. Les résultats obtenus concernent les : 1) SAMs aromatiques modèles de terphénylthiol (HS-(C₆H₄)₂-C₆H₅), stabilisables par réticulation sous irradiation. Une caractérisation vibrationnelle poussée de la SAM avant et après irradiation, en portant une attention particulière au comportement des modes d’élongation ν(CH), a permis d’opposer les processus de réactivité induite à 1, 6 et 50 eV.2) SAMs d’acide mercaptoundécanoïque (HS-(CH₂)₁ ₀ -COOH), les fonctions acides terminales permettant par exemple le greffage de peptides. L’interface SAM / environnement (COO-/COOH, eau résiduelle) a été caractérisée grâce à la forte sensibilité des modes d’élongation ν(OH) aux liaisons hydrogène. La démarche mise en place peut être facilement transposée à d’autres systèmes. / Self-Assembled Monolayers (SAMs) are good candidates to develop molecular platforms with controlled physico-chemical properties. A SAM is an ordered monolayer of bi-functionnal molecules. These molecules consist of an adjustable terminal function, separated from a headgroup by a chosen spacer chain. Thus, SAMs properties can be adjusted for the development of molecular electronic systems or (bio)-chemical sensors. Furthermore, additional chemical structuration can be induced by irradiation.Most current methods of irradiation involve high energy particles. The induced damages result from several competitive mechanisms (ionisations, excitations, dissociations). In this thesis, low energy electrons (0-20 eV) are used as primary particles, and the interaction processes between electrons and SAMs are studied in order to identify electron attachment resonances. At the associated energies, selective and effective dissociative processes can be induced to propose irradiation strategies leading to controlled and optimized chemical modifications.Model SAMs of thiols on gold are studied by a vibrational spectroscopy technique of strong surface sensibility, high resolution electron energy loss spectroscopy (HREELS). It allows at the same time to characterize SAMs and to probe electron-molecule interaction processes. The result obtained deal with : 1) Aromatic model SAMs of Terphenyl-thiol (HS-(C₆H₄)₂-C₆H₅), which can be stabilized by cross-linking under irradiation. Induced reactive processes at 1, 6 and 50 eV were compared and opposed, thanks to an advanced vibrational characterization of the SAM before and after irradiation, and by paying a particular attention to the stretching mode ν(CH) behaviour.2) Mercaptoundecanoic acid SAMs (HS-(CH₂)₁ ₀ -COOH), whose terminal functions allow for example the peptide anchoring. The interface SAM / environment (COO-/COOH, residual water) was characterized thanks to the strong sensitivity of the stretching modes ν(OH) to hydrogen bonding. The approach that was developped can be easily transposed to other systems.

Lorsque la matière condensée est soumise à des rayonnements de haute énergie, des électrons secondaires de basse énergie (0-20 eV) sont produits en grande quantité. Ces électrons participent à part entière aux dommages induits dans la matière, incluant les processus d’érosion et de modifications chimiques. Les fragments produits au sein du milieu réagissent et de nouvelles espèces sont formées. Plusieurs domaines d’application sont concernés par ces processus, et plus particulièrement le design de dispositifs par lithographie ou par dépôts assistés par faisceaux focalisés et l’astrochimie. Les enjeux concernent l’identification des mécanismes induits par les électrons lents, le contrôle des fragments réactifs et espèces stables formés, ainsi que la détermination de grandeurs quantitatives permettant d’apprécier l’efficacité des processus impliqués. L’approche développée dans ce travail de thèse consiste à irradier des surfaces et interfaces directement avec des faisceaux d’électrons de basse énergie afin d’étudier les processus induits. Les réponses de films moléculaires supportés modèles (d’épaisseur variable) sont étudiées en fonction de l’énergie incidente des électrons et des doses délivrées. Dans les cas favorables, des méthodologies ont pu être proposées pour accéder à l’estimation de sections efficaces effectives. Pour ce faire, trois techniques expérimentales sont combinées. Les films déposés et les résidus formés sont analysés par spectroscopie de perte d'énergie d’électrons à haute résolution (HREELS) et désorption programmée en température (TPD). Les fragments neutres (et non pas ioniques comme le plus souvent) désorbant sous irradiation sont analysés en masse afin de mener une étude de désorption stimulée par impact d’électrons (ESD).Dans le contexte de la fonctionnalisation de surface, le greffage de centres carbonés hybridés sp2 sur un substrat de diamant poly-cristallin hydrogéné a été réalisé par irradiation électronique d’une couche mince de benzylamine. A 11 eV, le mécanisme dominant implique la dissociation en neutres du précurseur. La section efficace effective de greffage a pu être déterminée par HREELS suite à une unique irradiation, en tirant avantage du profil du faisceau d’irradiation. Dans le contexte de l’astrochimie, la réponse à l’irradiation par électrons lents de glaces d’ammoniac amorphes et cristallisées a été étudiée. La désorption de molécules d’ammoniac a été observée. Elle peut résulter de l’érosion directe du film et de mécanismes de désorption induite par excitation électronique (DIET). Différents processus de fragmentation/recombinaison ont été mis en évidence via la désorption des espèces neutres NHx (x = 1,2), H2 et N2. Une chimie particulièrement riche est induite par irradiation électronique à 13 eV. L’analyse temporelle des rendements ESD a permis la détermination de la section efficace de la désorption de NH3, et l’observation de la formation retardée de N2 et H2. L’analyse TPD des résidus a démontré la synthèse de diazène (N2H2) et d’hydrazine (N2H4) dans le film. Ces résultats peuvent aider à l’élucidation des écarts observés dans les abondances de NH3 et N2 dans les régions denses de l'espace. Enfin, les premiers travaux réalisés pour fonctionnaliser un substrat de façon résolue à l’échelle micrométrique sous irradiation d’électrons lents sont également présentés. La faisabilité de la procédure utilisant un microscope électronique à basse énergie (LEEM) a été démontré sur une monocouche de terphenylthiol (TPT). Des motifs de 5 μm de travaux de sortie différents ont été imprimés en travaillant à des énergies de 10-50 eV. Ensuite la réponse de films modèles de résines lithographiques (PMMA, polyméthacrylate de méthyle) à des irradiations électroniques a été étudiée, afin d’identifier les énergies favorables en vue d’une modification de surface résolue spatialement. / High-energy irradiation of condensed matter leads to the production of copious amounts of low-energy (0-20 eV) secondary electrons. These electrons are known to trigger various dissociative processes leading to observed damages including erosion and chemical modifications. The resulting reactive species within the condensed media can also lead to the synthesis of new molecules. This has implications in several applications most especially in the design of lithographic methods, focused beam-assisted deposition, as well as in astrochemistry. In all these applications, it is important to identify the processes induced by low-energy electrons, study the reactive fragments and stable molecules produced to determine possibilities of controlling them, and generate quantitative data to gauge the efficiencies of these processes. The approach developed for this PhD work consists of directly irradiating surfaces and interfaces using low-energy electrons and studying the processes that arise. The responses of different model molecular films (of varying thickness) were studied as a function of incident electron energy and dose. In favorable cases, methodologies proposed herein can be used to estimate effective cross sections of observed processes. Three complementary surface-sensitive techniques were utilized for this purpose. To characterize the deposited films and formed residues, the High Resolution Electron-Energy Loss Spectroscopy (HREELS) and Temperature Programmed Desorption (TPD) were used. Neutral fragments (as opposed to their often-detected ionic counterparts) desorbing under electron irradiation were monitored using a mass spectrometer in a technique called Electron Stimulated Desorption (ESD).Within the context of surface functionalization, the grafting of sp2-hybridized carbon centers on a polycrystalline hydrogenated diamond substrate was realized through electron irradiation of a thin layer of benzylamine precursor deposited on its surface. At 11 eV, the dominant mechanism is proposed to be neutral dissociation of the precursor molecules. The effective cross section of the grafting process was estimated in only a single measurement from the HREELS map of the sample surface, taking advantage of the electron beam profile. Within the context of astrochemistry, on the other hand, the responses of crystalline and amorphous NH3 ices were studied under electron impact. The desorption of intact NH3 was observed which resulted in the direct erosion of the film proceeding through a mechanism consistent with desorption induced by electronic transitions (DIET). Different fragmentation and recombination processes were also observed as evidenced by detected neutral species like NHx (x=1,2), N2, and H2. Aside from desorption, a wealth of chemical processes was also observed at 13 eV. Temporal ESD at this energy allowed for the estimation of the effective cross section of NH3 desorption and observing the delayed desorption of N2 and H2. TPD analysis of the residues also provided evidence of N2H2 and N2H4 synthesis in the film. These results can help explain the observed discrepancies in abundances of NH3 and N2 in dense regions in space. Lastly, this PhD work will present prospects for these electron-induced processes to be constrained spatially in microscopic dimensions for lithographic applications. The feasibility of the procedure utilizing Low-Energy Electron Microscope (LEEM) was demonstrated on a terphenylthiol self-assembled monolayer (TPT SAM) specimen. Spots of 5 μm in diameter with different work functions were imprinted on the surface using energies from 10-50 eV. Electron-induced reactions in thin-film resists (PMMA, poly(methyl methacrylate)) were also studied at low-energy identifying opportunities for energy- and spatially-resolved surface modification.