The present thesis deals with synthesis of free alloy nanoparticles in immiscible alloy systems by the process of laser ablation under a liquid. In this process the alloy target is submerged in a liquid and the plume formed by the laser beam interaction with the target is confined in the liquid. The nanoparticles formed inside this plume and get quenched by the surrounding liquid yielding suspension of nanoparticles in the liquid. By the addition of suitable surfactants, these nanoparticles can be protected from other reactions and their size can be controlled by preventing further growth. We have selected immiscible alloys for the present study. These alloys tend to phase separate in melt as well as in solid depending on the value of the positive heat of mixing. We have used two binary alloys for the present study. These are alloys in Ag-Cu system and Fe-Cu system. In both these systems, there are reports of formation of extended solid solution due to kinetic factors during nonequilibrium processing like rapid solidification and mechanical alloying. In the present thesis we report synthesis of alloy nanoparticles of different compositions and sizes in these two systems and explore the nature of the phases that form in the small (nano) particles and their evolutionary pathways leading to the final microstructure. Microscopic techniques, especially transmission electron microscope, were used for characterization of these nanoparticles. The phase evolution was further studied using in situ microscopic techniques. After introducing the thesis in the Chapter 1, we describe briefly the relevant literatures in Chapter 2. The experimental details, in particular the experimental set up for laser ablation with targets under liquid are described in chapter 3. This chapter also includes the experimental details of the characterization. Transmission electron microscopy was used as primary characterization tool in the present study. The Chapter 4 presents the result of our study of alloy nanoparticles in Fe-Cu system. This system exhibits a submerged liquid miscibility gap. Although we have studied alloy targets of different compositions, the results of alloy nanoparticles obtained from targets with compositions Cu-40at.%Fe and Cu-60at.%Fe were primarily presented in this chapter. The nanoparticles that were synthesized had a size range of approximately 40nm to more than 100 nm. These particles have spherical morphology. The measurements of local compositions of different locations in the particle indicate the presence of a layer of Fe3O4 oxide at the spherical surface. This layer is devoid of copper. Most of the copper exist in the core of the particle. Fe rich spherical particles of much smaller size (~15 nm) are found to be embedded in the copper rich core. The copper formed solid solution with Fe and a copper concentration gradient exists in the particle below oxide layer due to oxidation of Fe. In contrast the nanoparticles obtained from alloy target with composition Fe-40at.% Cu have a spherical morphology. These have a composite structure with a Fe core in addition to Fe3O4 oxide layer at the surface. We have attempted to explain the phase evolution taking into account under cooling of the melt condensate that forms in the plume and their subsequent solidification through submerged miscibility gap. The chapters 5-7 deals with alloys of Ag-Cu system. In Chapter 5, we have carried out a detailed study of morphological evolution of the nanoparticles of Ag-Cu system. After optimizing the ablation parameters using pure Ag and Cu targets, we have synthesized alloy nanoparticles using different target compositions over the entire range of compositions with sizes having a mode of 25 nm. The evolution of the two phase structure is shown to be composition dependent with particles near equiatomic composition exhibit solid solution with uniformly distributed segregations of composition (Cu & Ag rich) while copper rich alloys exhibit a core shell structure with outer layer being Ag rich. The isothermal experiments again reveal emergence of core-shell morphology at intermediate time for particles with equiatomic composition. In order to compare the results of Ag-Cu nanoparticles with particles produced by other techniques we have synthesized Ag-Cu nanoparticles of near equiatomic composition by chemical route using nitrate salts and NaBH4 as reducing agent. PVP was used as capping agent. The results are presented in chapter 6. Depending on time of reaction, it is possible to synthesis free alloy particles from 2-3 nm to a network of chains. The nanoparticles contain Ag rich and Ag deficient region with Ag tends to segregate near surface. We have also presented mechanism for the formation of chain structure with prolonged reaction. The thermodynamic basis of phase formation in the immiscible system and evolution of phases under nonequilibrium situation have been discussed in chapter 7. This also includes a model to estimate size dependent surface energy. The analysis presented allows a discussion of possible pathways for phase evolution observed in the present work. The thesis ends with a final chapter that discussed the critical issues remains to be addressed and possible future work.

De nos jours, les nanomatériaux inorganiques sont devenus des objets importants pour de nombreuses applications. En même temps la pureté du matériau employé est le facteur clé, et souvent les méthodes de synthèse chimiques ne peuvent assurer l'absence d'une contamination résiduelle. Dans ce contexte, nous avons investigué et développé la synthèse par laser de nanoparticules d'or et de silicium en contrôlant leurs taille et composition. Cette technique se révèle être une approche entièrement physique de la fabrication des nanoparticules pures et exemptes d'agents tensioactifs et de sous-produits toxiques. L'approche engagé comprend deux étapes : 1) la génération de la suspension de micro- et nanoparticules par broyage mécanique, et par ablation préliminaire d'une cible solide ; 2) la fragmentation laser ultra-rapide de colloïdes en suspension qui aboutit à la formation de nanoparticules stables, non agrégées, cristallines et avec une faible dispersion de taille. Ce travail se concentre sur la synthèse de nanoparticules d'or de taille contrôlable entre 7 et 50 nm en absence de ligands. De plus, cette technique nous permet d'obtenir des nano-alliages bimétalliques et d'effectuer un couplage in situ de nanoparticules d'or avec des molécules organiques. Ensuite nous montrons la possibilité d'ajuster la taille moyenne et l'épaisseur de la couche d'oxyde des nanoparticules de Si en variant la concertation des particules initiale, le pH et la quantité d'oxygène dissoutes. Enfin, nous démontrons les propriétés optiques et plasmoniques des nanoparticules obtenues au cours de ce travail et leur potentiel pour les applications catalytiques et biomédicales. / Inorganic nanomaterials are of a major interest for numerous applications, specifically bioimaging, biomedicine, catalysis, and also surface enhanced Raman scattering spectroscopy. In most cases, the purity of the employed material is a key factor. Often the conventional chemical ways of synthesis cannot provide the desirable cleanliness. The aim of this thesis is to investigate and develop a laser-based synthetic concept for the fabrication of Au and Si-based nanoparticles with controlled parameters, free of surfactants and toxic by-products. The engaged approach includes two steps: 1) the generation of a raw suspension of micro- and nanoparticles by either mechanical milling or preliminary ablation of a target; 2) ultrafast laser-induced fragmentation from the suspended colloids leading to the formation of stable, non-aggregated, low-size dispersed and crystalline nanoparticles. In particular, we focus on the technique of the synthesis of bare Au nanoparticles with tunable size between 7 and 50 nm in the absence of any ligands. Moreover, this technique allows performing the in situ coupling of the Au nanoparticles with organic molecules and alloying at the nanoscale. Furthermore, we show the possibility of tuning the mean size and the thickness of the oxide shell of Si nanoparticles by varying the initial concentration of microparticles, the pH and the amount of dissolved oxygen. Finally, we demonstrate the optic and plasmonic properties of the nanoparticles synthesized by the techniques established in our work and their potential for the applications in catalysis and biomedicine.

La spectroscopie sur plasma induit par laser (LIBS) est une technique d'analyse élémentaire couplant l'ablation laser dans le cas des échantillons solides, à la spectroscopie d'émission atomique. Malgré de nombreux avantages qui en font une technique de plus en plus attractive, la spectroscopie LIBS n'est pas encore reconnue comme méthode d'analyse quantitative. En effet, les problèmes d'hétérogénéité des échantillons, d'effets matrice, d'auto-absorption des raies d'émission et surtout de manque de répétabilité participent à la dégradation des performances analytiques de la spectroscopie LIBS. Dans le but de faire évoluer la technique, ces travaux de thèse consistent à réaliser un cas particulier de démonstration de l'évaluation des performances analytiques d'un système LIBS de laboratoire en intégrant des notions de qualité. L'exemple porte ici sur l'analyse d'échantillons d'aciers certifiés. Une première étude concerne le déroulement de l'optimisation du système pour l'analyse quantitative. L'effet des différents paramètres expérimentaux sur le signal LIBS étant complexe, un protocole méthodique est indispensable. Une étude paramétrique est donc ici proposée en vue de déterminer les conditions expérimentales les plus propices à l'analyse quantitative. Une fois optimisée, la méthode LIBS est ensuite caractérisée grâce aux principes classiques de la validation de méthode. La justesse ainsi que la fidélité de la méthode sont évaluées dans des conditions de répétabilité et de précision intermédiaire. Cette dernière étude montre des résultats prometteurs pour la technique. L'application d'une carte de contrôle montre néanmoins un manque de stabilité du système de laboratoire et permet d'enclencher des actions correctives en vue d'améliorer ses performances analytiques. / Laser-Induced Breakdown Spectroscopy (LIBS) is an elemental analytical technique which combines laser ablation with atomic emission spectroscopy. LIBS spectroscopy has many advantages but is not recognized as a fully quantitative method. Indeed, the problem of samples' heterogeneity, matrix effects, self-absorption of emission lines and the lack of repeatability deteriorate the analytical performances of LIBS. In order to improve this technique, the work presented in this thesis includes an example of analytical performances evaluation with the use of quality notions of a laboratory LIBS system. The method is here specially applied to the analysis of certified steel samples. A first study deals with the optimization of the LIBS system for the quantitative analysis. As the effect of the different experimental parameters on LIBS signal is complex, a methodical protocol is necessary. Here, a parametric study is proposed to determine the experimental conditions suitable for quantitative analysis. Once optimized, the LIBS method is then characterized with basics of method validation. The trueness and the precision of the method are evaluated in conditions of repeatability and intermediate precision. This study shows promising results for LIBS technique. The application of a control chart reveals however an instability of the laboratory system and enables to introduce corrective actions to improve its analytical performances.

In this study we applied ultra-short laser pulses on a biological sample (Arabidopsis), in order to cut it precisely in a square pattern and subsequently use it for studying stress generation mechanisms. For this purpose, we utilized femtosecond laser pulses at 100 fs pulse width and 80 MHz repetition rate. We took two processing parameters into consideration such as laser power, laser exposure time which is related to the stage speed. Therefore, we were able to find the laser optimum conditions for ablation of biological tissues. The mutant and wildtype (control) obtained from laser cutting with a size of 500 µm × 500 µm were directly transferred (in-situ with laser cutting) into a microfabricated chamber containing ~500 nanoliters deionized water for measuring ion conductivity. The ion conductivity is a signature of cell-death mechanisms caused by various stresses. A light with intensity of 100 µmol was exposed to the samples for 2 hours and 20 minutes as a source of stress. A quantitative electrical analysis with high accuracy was assured by utilizing a microchamber, which enables a measurement in nanoliter volume. We measured the impedance which is reciprocal of conductivity using a lock-in amplifier and a precise current source at frequency of 130 Hz. Initially high impedance of mutant sample tended to drop within 2 hours and finally approached the constant value which signified that the cell death mechanism was complete. However, the wildtype sample demonstrated approximately constant impedance (conductivity) during the experiment.

Molecular motors, highly-efficient biological nano-machines, hold the potential to be employed for a wide range of nanotechnological applications. Towards this end, kinesin, dynein or myosin motor proteins are commonly surface-immobilized within engineered environments in order to transport cargo attached to cytoskeletal filaments. Being able to flexibly control the direction of filament motion – in particular on planar, non-topographical surfaces – has, however, remained challenging. Here, we demonstrate the applicability of a UV-laser-based ablation technique to programmably generate highly-localized patterns of functional kinesin-1 motors with different shapes and sizes on PLL-g-PEG-coated polystyrene surfaces. Straight and curved motor tracks with widths of less than 500 nm could be generated in a highly-reproducible manner and proved to reliably guide gliding microtubules. Though dependent on track curvature, the characteristic travel lengths of the microtubules on the tracks significantly exceeded earlier predictions. Moreover, we experimentally verified the performance of complex kinesin-1 patterns, recently designed by evolutionary algorithms, for controlling the global directionality of microtubule motion on large-area substrates.

Les nanoparticules métalliques (NPs) présentent des propriétés optiques (PO) uniques provenant de l’oscillation collective de leurs électrons. Cet effet se traduit par l'émergence d'une bande plasmon dont les caractéristiques peuvent être modulées par la taille, la forme, la nature des NPs et le milieu hôte. Il existe de nombreuses méthodes pour la préparation de ces NPs, l'une d'entre elles est l'ablation laser en milieu liquide (ALML). Cette technique offre certains avantages comme la simplicité, l’adaptabilité et des NPs dépourvues de contamination. Ses principaux inconvénients sont la productivité et le contrôle de la taille et de la forme des NPs. Ce travail est consacré à l'élaboration de NPs d’Ag par l’ALML et à l'étude théorique de leurs PO. Nous donnons dans ce manuscrit, les résultats de l'optimisation des paramètres d'élaboration conduisant à l'obtention de distributions en NPs reproductibles et contrôlées. Les PO de ces NPs sont mesurées et comparées à des modèles physiques spécifiques basés sur la théorie des milieux effectifs (EMT). L'EMT, telle que le modèle de Maxwell-Garnett, permet de décrire les PO de NPs monodisperses. Cependant, les voies de préparation classiques conduisent inévitablement vers des NPs montrant une distribution de forme et de taille qui induit des changements drastiques sur leurs PO. Le modèle SDEMT est proposée pour le calcul de la fonction diélectrique effective et du coefficient d'absorption de solutions colloïdales de NPs métalliques. Contrairement à Maxwell-Garnett, ce modèle donne une meilleure description des spectres d'absorption et d’ellipsométrie mesurés sur des échantillons contenant des NPs d’Ag et d’Au / Metal nanoparticles (NPs) exhibit unique optical properties (OP) coming from the collective oscillations of their electrons. This effect is translated by the emergence of a band of plasmon, the characteristics which can be modulated by the size, the shape and the nature of the NPs as well as by the environment of the host. There are many methods for the preparation of NPs, and one of them is the pulsed-laser ablation in liquid (PLAL). This technique offers some advantages such as simplicity, versatility and surface NP without contamination (reducing agent residues and/or stabilizers). Its main drawbacks are the lacks of productivity and control of the NP size and shape. This work is devoted to elaboration of Ag NPs by PLAL and theoretical investigation of their OP. We give here the results about the optimization of elaboration parameters leading to obtaining reproducible and controlled distributions of Ag NPs. The OP of these NPs are measured and compared to specific physical models based on the effective medium theory (EMT). Classical EMT such as Maxwell Garnett approximation allows describing the OP of monodisperse NPs. However, conventional preparation routes unavoidably conduct to NPs showing a shape and a size distribution which induces drastic changes in the OP. A SDEMT model which considers the shape dispersion is proposed for the calculation of the effective dielectric function and absorption coefficient of colloidal solution of metal NPs in water. Contrary to the conventional theory, this model gives a better description of the measured absorption and ellispometry spectra of sample containing Ag and Au NPs

Der selektive Abtrag dünner Schichten findet für eine Vielzahl technischer Fertigungsverfahren Anwendung. Eine solche ist die Herstellung organischer Solarzellen, bei der mittels Laserabtrag die Funktionsschichten strukturiert werden, um eine monolithische Verschaltung zu erreichen. Aus Gründen der Lebensdauerverbesserung und zur Kostenreduktion gibt es Bestrebungen verschiedene Funktionalitäten wie Trägermaterial der Solarzellen und Wasserdampfbarriere zusammenzuführen. Im Rahmen der vorliegenden Dissertation wird der Abtrag von elektrisch leitfähigen, transpa-renten Schichten auf einer Wasserbarriereschicht aus Siliziumnitrid untersucht. Das Ziel ist ein vollständiger Abtrag der Elektrode zur elektrischen Separation, bei gleichzeitiger Erhaltung der Barriereeigenschaften der darunterliegenden Schicht. Die Untersuchungen zum Abtragsverhal-ten zeigen Schwankung in der Abtragsqualität der Elektrode. Mit Hilfe von Raman-Spektroskopie und der entwickelten Kontrastscan Methode kann gezeigt werden, dass diese Inhomogenität von Bereichen schwankender Brechzahl in der verwendeten Polyethylentereph-thalatfolie verursacht sind. Diese entstehen bei der Herstellung der Folie durch den Prozess des Verstreckens, um eine thermische Stabilisierung zu erreichen. Zur Entwicklung eines tieferen Verständnisses der Einflüsse auf die Abtragsqualität wird ein Simulationsmodell entwickelt. Es simuliert die optischen Gegebenheiten des gesamten Schichtverbunds und nutzt die ermittelten, lokal absorbierten Leistungen für die Berechnung der thermomechanischen Gegebenheiten in den Schichten nach dem Zwei-Temperatur-Modell. An Hand von Abtragsergebnissen zum Elektrodensystem Indiumzinnoxid (ITO) werden die Er-gebnisse des entwickelten Simulationsmodells mit dem bekannten Modell zur Absorption nach Lambert-Beer verglichen. Für ITO und einen weiteren Elektrodentyp, genannt Dielektrikum-Metall-Dielektrikum (DMD), wird die Übereinstimmung von Simulation und experimentellen Er-gebnissen zur Abtragsschwelle, der Breite des Elektrodenabtrags und zur Beeinflussung der Barriereschicht gegenübergestellt und diskutiert. Auf Basis der Erkenntnisse aus dem entwi-ckelten Simulationsmodell ist es gelungen prozesstechnische Anpassungen zu identifizieren, welche die Auswirkungen der lokalen Brechzahlschwankungen reduzieren. Durch Überführung der entwickelten Prozessabfolge auf eine Rolle-zu-Rolle-Bearbeitung wird schließlich die Ska-lierbarkeit nachgewiesen.:1 Einleitung 2 Stand der Technik 2.1 Herstellung organischer Solarzellen 2.2 Verkapselung organischer Elektronik 2.3 Flexible Barrieren 2.4 Laserprozessierung von funktionalen Schichten in der organischen Elektronik 2.5 Laserprozessierung auf flexiblen Barrieren 3 Motivation 4 Grundlagen 4.1 Physikalsiche Grundlagen 4.1.1 Verhalten elektromagnetischer Wellen an Grenzflächen 4.1.2 Lichtinterferenz und Transfermatrixmethode 4.1.3 Energieeintrag durch Absorption 4.1.4 Physikalische Effekte bei der Laser-Materie-Wechselwirkung 4.1.5 Das Zwei-Temperatur-Modell 4.1.6 Zusammenhang von Elektronendichte und Absorption 4.1.7 Generierung freier Ladungsträger 4.2 Materialgrundlagen 4.2.1 Herstellung von thermisch stabilisierten PET 4.2.2 Aufbau des verwendeten Barrieresystem 4.2.3 Herstellung und Eigenschaften der verwendeten Schichten 5 Experimentelle Arbeit und Simulation 5.1 Mess- und Analysemethoden 5.1.1 Spektrale Charakterisierung der Elektrodenschichten 5.1.2 Auflichtmikroskopie 5.1.3 Konfokalmikroskopie 5.1.4 Test auf Barriereintegrität 5.1.5 Messung des Isolationswiderstands 5.1.6 Parametertest an funktionellen Solarzellen 5.2 Laserbearbeitung 5.2.1 Laserauswahl 5.2.2 Strahlformung 5.2.3 Untersuchungen des Laserabtrags 5.2.4 Versuchsaufbau 5.3 Simulationsmodell 5.3.1 Simulationsmodell mit Absorption nach Lambert-Beer 5.3.2 Simulationsmodell mit Absorption durch Interferenzeffekten 6 Ergebnisse und Diskussion 6.1 Optische Eigenschaften der Schichten und Ermittlung von Kennwerten 6.2 Strahlcharakterisierung 6.3 Kontrastscan 6.4 Prozessentwicklung 6.4.1 Abtragsschwelle der Barriere 6.4.2 Laserabtrag der ITO-Elektrode 6.4.3 DMD-Bearbeitung 6.5 Rolle zu Rolle Prozessierung 6.5.1 Charakterisierung des Bandmaterials 6.5.2 Einzelpulsabtrag 6.5.3 Prozessfenster und Überführung auf die R2R-Laseranlage 7 Zusammenfassung 8 Literaturangaben 9 Anhang 9.1 Strahlvermessung zur Gaußsche Energieverteilung 9.2 Verwendung des VORTEX doE – Justage und resultierende Energieverteilung 9.3 Generierung einer TopHat Verteilung mit dem FBS DOE 9.4 ITO Abtrag mit dem Vortex-DOE 9.5 Prozessieren der DMD Varianten mit Alternative Energieverteilungen 9.6 Abtragsschwellen für Intensitäten 9.7 Weitere elektrische Ergebnisse

Die Analyse von organischen Polymeren mittels Massenspektrometrie mit induktiv gekoppeltem Plasma nach Laserablation unterliegt starken Matrixeffekten. Mögliche Korrekturmodelle sollten basierend auf der tatsächlich ablatierten Elementmasse sowie der Signalintensität des Kohlenstoffisotops C-13 (13C-Korrektur) entworfen werden. Damit die 13C-Korrektur erfolgreich verlaufen kann, ist ein direkter Zusammenhang zwischen ablatiertem Kohlenstoff und gemessenem 13C-ICP-MS Signal erforderlich. Dies wurde überprüft, indem unter Anwendung der konfokalen Mikroskopie das Ablationskratervolumen bestimmt und der ablatierte Kohlenstoff berechnet wurde. Dieser Zusammenhang konnte sowohl für undotierte, wie auch für elementdotierte Polymere und die Verwendung verschiedener Ablationsgase (Helium, Argon und Sauerstoff) ermittelt werden. Eigens hergestellte polymere elementdotierte Standardmaterialien wurden hinsichtlich der Matrixeffekte charakterisiert. Als größter Einflussfaktor stellte sich die unterschiedliche Ablationsrate bei der Ablation verschiedener Polymere heraus. Unter Anwendung der tatsächlich ablatierten Elementmasse sowie unter Anwendung der 13C-Korrektur konnte die Matrixabhängigkeit deutlich verringert werden.

Laser Ablation Inductively coupled plasma mass spectrometry (LA-ICP-MS) and Raman spectroscopy are both powerful imaging techniques. Their applications are numerous and extremely potential in the field of biology. In order to improve upon LA-ICP-MS an in-house built cold cell was developed and its effectiveness studied by imaging Brassica napus seeds. To further apply LA-ICP-MS and Raman imaging to the field of entomology a prong gilled mayfly (Ephemeroptera: Leptophlebiidae) from the Róbalo River, located on Navarino Island in Chile, was studied. Analysis of both samples showcased LA-ICP-MS and Raman spectroscopy as effective instruments for imaging trace elements and larger molecules in biological samples respectively.

[pt] O espaço interplanetário contem partículas de poeira cósmica originárias do meio interestrelar ou que são produtos da erosão de Asteroides, Meteoróides e Cometas. As partículas que chegam à superfície da Terra são chamadas de micro-meteoritos. Os micrometeoritos participam dos processos de erosão da superfície terrestre e, por isso, são estudados para se ter uma melhor compreensão da evolução do nosso planeta e do Sistema Solar. Um novo programa de pesquisa iniciado em 2016 no Departamento de Física da PUC-Rio tem os objetivos de 1) desenvolver um meio experimental para simular os impactos de micrometeoritos com a superfície terrestre e 2) analisar, as mudanças físico-químicas causadas pelos impactos nos minerais terrestres. A fim de simular o impacto dos micrometeoritos, empre-gou-se a técnica de Ablação por Laser, o que permitiu fazer deposições a taxas controladas de energia em áreas determinadas das amostras. Para este trabalho foram escolhidas amostras dos silicatos mais abundantes encontrados na crosta terrestre, como jadeíta, quartzo e feldspato. A ablação dos silicatos foi efetuada em dois meios: amostra no ar ou amostra em H2O. A principal técnica analítica utilizada foi a espectroscopia Raman. Complementarmente foram utilizadas a micros-copia óptica e a perfilometria. Um total de cerca 500 espectros Raman foram obti-dos, e várias bandas para cada amostra nos dois meios, antes e depois da ablação, foram analisadas estatisticamente. A análise energética e morfológica dos impactos por laser mostrou que a técnica de ablação por laser é razoavelmente boa para simular os impactos dos micrometeoritos com a crosta terrestre. A análise dos espetros Raman mostrou que depois da ablação, tanto no ar como em H2O deionizada, os três silicatos apresentaram modificações na intensidade, na largura e na posição do centro de várias das suas bandas principais. Constatou-se que, quando há modificações, o comportamento é o mesmo para todos os silicatos: deslocamento dos centros das bandas para números de onda menores. Os resultados da análise por espectroscopia Raman são encorajantes para a utilização desta técnica na caracterização e interpretação das mudanças espectrais e estruturais na superfície terrestre depois do impacto de micrometeoritos. Este trabalho, no melhor do nosso conheci-mento, nunca foi feito. A perspectiva é dar continuidade a esta linha de pesquisa, aumentando o número de experimentos de ablação por laser e estendendo a análise das amostras irradiadas a outras técnicas de caracterização complementares a espetroscopia Raman (espetroscopia UV-Vis-NIR, FTIR, ....). Além disso, numa fase futura de estudo, serão estudadas amostras mais complexas, onde material orgânico será adicionado aos silicatos já estudados. / [en] The interplanetary space contains particles of cosmic dust that come from the interstellar medium, or that are the product of the erosion of Asteroids, Meteoroids and Comets. The particles that reach the Earth s surface are called micrometeorites. Micrometeorites participate in the erosion processes of the Earth s surface and, therefore, are studied in order to have a better understanding of the evolution of our planet and the Solar System. A new research program was initiated in 2016 in the Department of Physics of PUC-Rio with the objectives of 1) finding an experimental means to simulate the impacts of micrometeorites with the terrestrial surface, and 2) analyzing the physical-chemical changes caused by the impacts on terrestrial minerals. In order to simulate the impact of micrometeorites the Laser Ablation technique was employed, which allowed us to make energy depositions at controlled rates in certain areas of the samples. For this work, we chose samples of the most abundant silicates found in the earth s crust, such as jadeite, quartz and feldspar. The ablation of the silicates was carried out in two medium: the sample in air, and the sample in H2O. The main analytical technique used was Raman spectroscopy. In addition, optical microscopy and profilometry were used. About 500 Raman spectra were obtained, and several bands for each sample and in each medium, before and after ablation, were statistically analyzed. The energetic and morphological analysis of the laser impacts showed that the technique of laser ablation is reasonably good to simulate the impacts of micrometeorites with the terrestrial crust. The analysis of the Raman spectra showed that after the ablation, in air as well as in deionized H2O, all three silicates presented modifications in the intensity, width and position of the center of several of their main bands. It was found that, when there were modifications, the behavior was the same for all silicates: a shift of the center of de bands to smaller wavelengths. The results of the analysis by Raman spectroscopy are encouraging to use this technique in the characterization and interpretation of the spectral and structural changes in the terrestrial surface after the impact of micrometeorites. This work, to the best of our knowledge, has never been done before. Its perspective is to give continuity to this line of research, incrementing the amount of experiments by laser ablation and extending the analysis of the irradiated samples to other characterization techniques that complement Raman spectroscopy (UV-Vis-NIR spectroscopy, FTIR, …). Also, in future studies, more complex samples will be studied, where organic material will be added to the already studied silicates.