We employ an extreme ultraviolet (XUV) pulse to impulsively excite dipole polarization in atoms or molecules, which corresponds to coherently prepared superposition of excited states. A delayed near infrared (NIR) pulse then perturbs the fast evolving polarization, and the resultant absorbance change is monitored in dilute helium, dense helium, and sulfur hexafluoride (SF6) molecules. We observe and quantify the time-dependence of various transient phenomena in helium atoms, including laser-induced phase (LIP), time-varying (AC) Stark shift, quantum path interference, and laser-induced continuum structure. In the case of dense helium targets, we discuss nonlinear macroscopic propagation effects pertaining to LIP and resonant pulse propagation, which account for the appearance of new spectral features in transient lineshapes. We then use tunable NIR photons to demonstrate the wavelength dependence of the transient laser induced effects. In the case of molecular polarization experiment in SF6, we show suppression of XUV photoabsorption corresponding to inter-valence transitions in the presence of a strong NIR field. In each case, the temporal evolution of transient absorption spectra allows us to observe and understand the transient laser induced modifications of the electronic structure of atoms and molecules.

Quantum mechanical motion of electrons in atoms and molecules is at the heart of many photophysical and photochemical processes. As the natural timescale of electron dynamics is in the range of femtoseconds or shorter, ultrashort pulses are required to study such phenomena. The ultrashort pulse light-matter interaction at high intensity regime can however dramatically alter the atomic and molecular structures. Our current understanding of such transient electronic modification is far from complete, especially when complicated light-induced couplings are involved. In this dissertation, we investigated how a femtosecond strong-field pulse can control or modify the evolution of atomic or molecular polarization, representing electric dipole excitation in various systems. Extreme ultraviolet (XUV) attosecond pulse trains are used to coherently prepare superposition of excited states in various atomic and molecular systems. A subsequent phase-locked infrared (IR) femtosecond pulse is applied to perturb the dipoles, and transient changes in the transmitted XUV spectra are measured. This scheme is termed as XUV attosecond transient absorption spectroscopy. In the first study, we applied this technique to study the modification of Rydberg states in dilute helium gas. We observed several transient changes to the atomic structure, including the ac Stark shift, laser-induced quantum phase, laser-induced continuum structure, and quantum path interference. When the experiments were extended to the study of a dense helium gas sample, new spectral features in the absorption spectra emerged which cannot be explained by linear optical response models. We found that these absorption features arise from the interplay between the XUV resonant pulse propagation and the IR-imposed phase shift. A unified physical model was also developed to account for various scenarios. Extending our work to argon atoms, we studied how an external infrared field can be used to impulsively control different photo-excitation pathways and the transient absorption lineshape of an otherwise isolated autoionizing state. It is found that by controlling the field polarization of the IR pulse, we can modify the transient absorption line shape from Fano-like to Lorentzian-like profiles. Unlike atoms, in our study of autoionizing states of the oxygen molecule, we observed both positive and negative optical density changes for states with different electronic symmetries. The predictions of two distinct and simplified dipole perturbation models were compared against both the experimental results and a full theoretical calculation in order to understand the origin of the sign of absorption change. We relate this symmetry-dependent sign change to the Fano parameters of static photoabsorption. The same approach was applied to study molecular nitrogen, in which we observed the decay dynamics of IR perturbed doubly-excited Rydberg states with many vibrational progressions. In addition, we also conducted experiments to investigate Rydberg state dynamics of other molecular systems such as carbon dioxide. In summary, we experimentally explored the ephemeral light-induced phenomena associated with excited states of atoms and molecules. These studies provide real-time information on ultrafast electronic processes and provide strategies for direct time-domain control of the light-matter interaction.

La communauté scientifique s’accorde sur la responsabilité de l’homme dans les menaces actuelles pesant sur la biodiversité. La forte érosion de la biodiversité mondiale pointe les limites biophysiques de renouvellement du capital naturel (espèces, paysages, services écosystémiques…). Postulant que la durabilité d’un système économique passe par le maintien du stock de capital naturel, Costanza et Daly ont introduit les concepts de « durabilité faible » et de « durabilité forte » pour caractériser les biens selon leur niveau de substituabilité (dans le cadre de la durabilité forte, le capital naturel devient non substituable). A leur suite, afin d’adapter le concept de durabilité forte aux problématiques de développement et d’aménagement, Toman suggère en 1994 de distinguer les capitaux naturels critiques présentant des enjeux de préservation forts des capitaux naturels de moindre importance. Il propose d’appliquer une logique de durabilité forte aux premiers pour ne pas les laisser décroître en dessous de seuils donnés dits normes minimales de sauvegarde et, d’utiliser les seconds comme supports du développement, appliquant alors une logique de durabilité faible.Partant les cadres conceptuels de Costanza, Daly et Toman, ma thèse évalue la faisabilité et les arbitrages inhérents à la mise en œuvre de la durabilité forte dans une action publique de préservation de la biodiversité, en l’occurrence, la compensation écologique qui conditionne les opérations d’aménagement à compenser les pertes écologiques qu’ils engendrent. Mon objectif fut de me centrer sur une action publique ayant des assises spatiales afin de mettre en évidence les déterminants individuels permettant sa mise en œuvre et d’évaluer les seuils, notamment spatiaux, nécessitant des arbitrages entre enjeux de développement économique et conservation de la biodiversité.Dans un premier chapitre, je propose et applique empiriquement sur trois régions françaises, une méthode pluridisciplinaire (reprenant des éléments d’écologie) de catégorisation des milieux naturels en fonction de leur niveau de durabilité. La spatialisation empirique de mes catégories fait ressortir la place prédominante de l’agriculture et une forte variabilité des niveaux de durabilité selon la nature biophysique et anthropique des espaces. Dans le second chapitre, j’évalue, à partir des cadres de l’économie comportementale, l’acceptabilité de la compensation écologique par les agriculteurs. Je mets en évidence de fortes disparités dépendantes des types de production et de l’histoire personnelle des agriculteurs. Dans mon dernier chapitre, j’évalue empiriquement les contraintes spatiales inhérentes à l’atteinte d’une durabilité forte à partir d’un modèle théorique d’allocation de l’effort de compensation à l’échelle régionale. Un premier résultat de ma thèse est donc une définition opératoire de la nature ordinaire, adaptée à la mise en œuvre d’une action publique sur l’environnement (en l’occurrence le dispositif de compensation écologique). Je montre que, si l’on cantonne les aménagements à la nature ordinaire, l’objectif de durabilité forte devient atteignable, à condition que l’agriculture soit le pivot du dispositif. Mon second résultat met en lumière les comportements des agriculteurs eu égard aux politiques visant la préservation d’une biodiversité. Il montre, à rebours des résultats standard en économie comportementale, que les agriculteurs réagissent plus favorablement à une biodiversité moins spécifique et que les niveaux d’acceptabilité de la mesure sont hétérogènes selon leur type de production (bio vs conventionnel) et leur histoire personnelle (héritier agricole versus néo-agriculteur). / Non fourni

Les pérovskites hybrides organiques-inorganiques ont attiré l'attention en raison de leurs applications potentielles dans des dispositifs optiques et plus récemment dans les dispositifs photovoltaïques. L'arrangement cristallin des pérovskites forme une structure en multi-puits quantiques dans laquelle les états excitoniques présentent une grande force d'oscillateur et une énergie de liaison importante, ce qui rend la réalisation de microcavités dans le régime de couplage fort possible à la température ambiante. Etant un matériau relativement nouveau, les pérovskites ont encore beaucoup de comportements qui ne sont pas bien compris et beaucoup de travail de recherche est nécessaire. Ce manuscrit est divisé en deux parties. Dans la première partie, la dynamique des excitons sur une pérovskite particulière (C6H5-C2H4-NH3)2PbI4 (PEPI) est étudiée à température ambiante par mesure de type pompe-sonde sous faible et fort régime d'excitation. Sous forte densité d'excitation, un processus de recombinaison Auger des excitons est présent. Une relaxation intrabande ultra-rapide a été observée. La deuxième partie du manuscrit est consacrée à l'étude de la microphotoluminescence à temperature ambiante de microcavités à base de PEPI à haut facteur de qualité. Des nouvelles pérovskites avec des propriétés optimisées (propriétés optiques d'émission, rugosité de surface et photostabilité) ont également été synthétisées. / The reason for choosing this thesis comes from the fact that in the near future,I would like to gain more knowledge and experience in scientific research and especially in the study of non linear effects in optical microcavities where new opportunities are opened and high efficient light sources could be exploited.In last ten years, an increasing number of studies are dedicated on hybrid organic-inorganic materials, due to the possibility of combining the properties both of inorganic(high mobility, electrical pumping, band engineering ) and of organic materials (low cost technology, high luminescence quantum yield at room temperature).In this context , organic-inorganic perovskites having a chemical formula (R-NH3)2MX4 where M is a metal, X halogen and R an organic chains presents a natural hybrid system . When deposited by spin coating, the molecules self-organize to form a multiple quantum wells structure. Because of the strong binding energy, optical features can be seen at room temperature. Moreover, such pervoskite presents great flexibility in their optical properties such that the spectral position of the excitonic transitions can be tailored by substituting different halides X, and the photoluminescence efficiency can be tailored by changing the organic part R. This kind of perovskites has been studied both for fundamental studies and for applications in optoelectronics. In order to increase the coupling between light and matter (exciton), perovskite has been inserted in planar microcavity and strong coupling regime has been achieved at room temperature. The strong coupling of light with exciton give rise to polariton quasi-particles, which have new properties not seen in either photons or excitons. In order to go further and have better study in stimulated scattering of polaritons in these microcavities ,a better understanding of the electronic structure as well as the excitonic interactions in these quantum wells are necessary due to the lack of information on the dynamic and on the carrier interaction of these structures. In order to study the hybrid polaritons, it will be first necessary to improve the knowledge about the relaxation in the perovskite layers. So, ultrafast pump-probe experiments will be performed on hybrid microcavities, and also on perovskite layers.

A plasmônica tem chamado atenção nos últimos anos como um candidato viável para substituir a indústria eletrônica, assim como interação dos plásmons com a matéria devido a suas propriedades exóticas. O confinamento destes plásmons de superfície em nanoestruturas metálicas fabricadas com técnicas de litografia óptica, eletrônica e de íons cada vez mais avançadas, abriu a possibilidade de desenvolver vários modelos de dispositivos ópticos que trabalham na região do visível. Além disso, o estudo da interação de plásmons poláritons de superfície com emissores quânticos nas proximidades de nanoestruturas metálicas permite manipular as propriedades tanto dos plásmons como dos emissores quânticos. Tanto a preparação como a análise de amostras em plasmônica necessitam de técnicas capazes de investigar sistemas em nanoescala. Neste trabalho, investigamos a interação de plásmon poláritons confinados numa superfície de ouro com átomos artificiais, i.e. os emissores quânticos são pontos quânticos numa matriz de InAs/GaAs. Para isso, empregamos a análise da interação dos plásmons confinados numa grade metálica, com dimensões características abaixo do comprimento de onda da luz utilizada, assim como um sistema simples composto por uma na camada de ouro capaz de confinar plásmons em duas dimensões. A análise da interação com os estados de energia dos éxcitons nos pontos quânticos foi feita empregando medidas de micro-fotoluminescência a 77K e medidas de tempo de vida. Nos sistemas compostos pelas grades metálicas, observamos que é possível manipular a relação do espectro de luminescência correspondente a cada estado de energia do éxciton. Já no sistema composto pelo filme metálico simples, foi possível modificar o tempo de vida do estado fundamental do éxciton apenas modificando o cap layer da camada de pontos quânticos. / Plasmonics has drawn attention in recent years as a viable candidate to replace the electronics industry, as well as the interaction of plasmons with matter due to its exotic properties. The confinement of these surface plasmons in metal nanostructures made of increasingly advanced optical, electronic and ionic lithography techniques, opened the possibility of developing various models of optical devices working in the visible spectrum. Moreover, the study of interaction of surface plasmon polaritons with quantum emitters nearby metallic nanostructures opens a path to manipulate the properties of both plasmons and the quantum emitters. Both the preparation and analysis of samples in plasmonics require techniques capable of investigating nanoscale systems. In this thesis, we investigate the interaction of plasmon polaritons confined to a golden metallic surface with artificial atoms, i.e. quantum emitters consisting of quantum dots in a matrix of InAs/GaAs. For this, we used the analysis of the interaction of plasmons confined in a metallic grating with characteristic dimensions below the wavelength of light used, as well as a simple system composed of a thin gold layer which can confine plasmons in two dimensions. The analysis of the interaction with the exciton energy states in quantum dots was made using micro-photoluminescence measurements at 77 K and lifetime measurements. In systems composed by metal gratings, we note that it is possible to manipulate the relationship of the corresponding luminescence spectrum for each exciton energy state. In the system composed of the simple metal lm, it was possible to modify the ground state lifetime of the exciton only modifying the cap layer of the quantum dot layer.

In this thesis, I develop and combine strong lensing and dynamical probes of the mass of early-type galaxies (ETGs) in order to improve our understanding of their dark and luminous mass structure and evolution. Firstly, I demonstrate that the dark matter halo of our nearest brightest cluster galaxy (BCG), M87, is centrally cored relative to the predictions of dark-matter-only models, and suggest an interpretation of this result in terms of dynamical heating due to the infall of satellite galaxies. Conversely, I find that the haloes of a sample of 12 field ETGs are strongly cusped, consistent with adiabatic contraction models due to the initial infall of gas. I suggest an explanation for these differences in which the increased rate of merging and accretion experienced by ETGs in dense environments leads to increased amounts of halo heating and expansion, such that the signature of the halo's initial contraction is erased in BCGs but retained in more isolated systems. Secondly, I find evidence that the stellar-mass-to-light ratio declines with increasing radius in both field and cluster ETGs. With M87, I show that the strength of this gradient cannot be explained by trends in stellar metallicity or age if the stellar initial mass function (IMF) is spatially uniform, but that an IMF which becomes increasing bottom-heavy towards the galaxy centre can fully reproduce the inference on the stellar mass. Finally, I use the sizes, stellar masses and luminous structures of two samples of massive ETGs at redshift z ~ 0.6 to set constraints on the mechanisms of ETG growth. I find that ETGs in dense cluster environments already lie on the local size-mass relation at this redshift, contrary to their isolated counterparts, and suggest that this may be evidence for their accelerated growth at early times due to the higher incidence of merger events in clusters. I also show that massive compact ETGs at this redshift are composed of a compact, red, spheroidal core surrounded by a more extended, diffuse, bluer envelope, which may be a structural imprint of their ongoing inside-out growth. Overall, the studies presented in this thesis suggest a coherent scenario for ETG evolution which is dominated by hierarchical processes.

No description available.

A plasmônica tem chamado atenção nos últimos anos como um candidato viável para substituir a indústria eletrônica, assim como interação dos plásmons com a matéria devido a suas propriedades exóticas. O confinamento destes plásmons de superfície em nanoestruturas metálicas fabricadas com técnicas de litografia óptica, eletrônica e de íons cada vez mais avançadas, abriu a possibilidade de desenvolver vários modelos de dispositivos ópticos que trabalham na região do visível. Além disso, o estudo da interação de plásmons poláritons de superfície com emissores quânticos nas proximidades de nanoestruturas metálicas permite manipular as propriedades tanto dos plásmons como dos emissores quânticos. Tanto a preparação como a análise de amostras em plasmônica necessitam de técnicas capazes de investigar sistemas em nanoescala. Neste trabalho, investigamos a interação de plásmon poláritons confinados numa superfície de ouro com átomos artificiais, i.e. os emissores quânticos são pontos quânticos numa matriz de InAs/GaAs. Para isso, empregamos a análise da interação dos plásmons confinados numa grade metálica, com dimensões características abaixo do comprimento de onda da luz utilizada, assim como um sistema simples composto por uma na camada de ouro capaz de confinar plásmons em duas dimensões. A análise da interação com os estados de energia dos éxcitons nos pontos quânticos foi feita empregando medidas de micro-fotoluminescência a 77K e medidas de tempo de vida. Nos sistemas compostos pelas grades metálicas, observamos que é possível manipular a relação do espectro de luminescência correspondente a cada estado de energia do éxciton. Já no sistema composto pelo filme metálico simples, foi possível modificar o tempo de vida do estado fundamental do éxciton apenas modificando o cap layer da camada de pontos quânticos. / Plasmonics has drawn attention in recent years as a viable candidate to replace the electronics industry, as well as the interaction of plasmons with matter due to its exotic properties. The confinement of these surface plasmons in metal nanostructures made of increasingly advanced optical, electronic and ionic lithography techniques, opened the possibility of developing various models of optical devices working in the visible spectrum. Moreover, the study of interaction of surface plasmon polaritons with quantum emitters nearby metallic nanostructures opens a path to manipulate the properties of both plasmons and the quantum emitters. Both the preparation and analysis of samples in plasmonics require techniques capable of investigating nanoscale systems. In this thesis, we investigate the interaction of plasmon polaritons confined to a golden metallic surface with artificial atoms, i.e. quantum emitters consisting of quantum dots in a matrix of InAs/GaAs. For this, we used the analysis of the interaction of plasmons confined in a metallic grating with characteristic dimensions below the wavelength of light used, as well as a simple system composed of a thin gold layer which can confine plasmons in two dimensions. The analysis of the interaction with the exciton energy states in quantum dots was made using micro-photoluminescence measurements at 77 K and lifetime measurements. In systems composed by metal gratings, we note that it is possible to manipulate the relationship of the corresponding luminescence spectrum for each exciton energy state. In the system composed of the simple metal lm, it was possible to modify the ground state lifetime of the exciton only modifying the cap layer of the quantum dot layer.

Master of Science / Department of Physics / Itzhak Ben-Itzhak / Ultrafast lasers allow us to study molecular dynamics on their natural timescale. The electronic dynamics can be studied using attosecond pulses, while the vibrational and rotational dynamics can be probed using tens of femtosecond and picosecond laser pulses, respectively. This capability has led to a broad understanding of the electronic dynamics in atoms and molecules as well as vibrational and rotational dynamics of molecules, which is one of the important goals in basic science. Moreover, it is possible to control quantum mechanical processes using ultrafast intense lasers. In this thesis, we focus on a couple of experiments. The first involves quantum control of the formation of neutral molecular fragments while the second focuses on three-body fragmentation of molecules employing the native-frames analysis method, which was recently introduced by our group [J. Rajput et al., Phys. Rev. Lett. 120, 103001 (2018)]. Experimental studies focused on the formation of excited neutral D fragments from D2 molecules are presented. We show that by manipulating the chirp of the intense laser pulses, i.e. the “time order” of the frequency components within the pulse, the formation of these fragments is controlled. To achieve this control we implement a single-prism compressor to manipulate the chirp of the laser pulses. Three-body fragmentation of CO₂ resulting in C+ + O+ + O+ is also studied. We show that if the two bonds break in a two-step process, i.e. a sequential breakup, the pathways from which the two identical O+ fragments originate can be separated using the native-frames analysis method. In contrast, the two O+ fragments cannot be distinguished if the two C-O bonds break simultaneously.

Orientador: Leila Trevisan Braz / Resumo: A melancieira é uma hortaliça amplamente cultivada no Brasil, sendo consumida por todas as classes sociais. A enxertia vem sendo utilizada para esta cultura em muitos países e os benefícios são no controle de doenças, principalmente as de solo; na maior absorção de nutrientes, melhor eficiência no uso da água, aumento da tolerância a temperaturas extremas, aumento da tolerância à salinidade e ao encharcamento, proporcionando, assim, melhor produtividade e qualidade dos frutos. Diante do exposto, foi avaliado o desempenho de três porta-enxertos (‘Strong Tosa’, ‘Super Shintosa’ e ‘Carnivor’) para a melancia ‘Manchester’. Os experimentos foram conduzidos em 2016, na cidade de Holambra-SP, e, em 2017, nas cidades de Itápolis--SP e Holambra-SP. Em cada experimento, foi utilizado o delineamento em blocos casualizados, com cinco tratamentos e quatro repetições. Foram avaliadas as características de desenvolvimento da planta, produção e qualidade do fruto para todos os experimentos, além de teores de nutrientes da parte aérea e do fruto, nos experimentos realizados em Holambra-SP. A partir dos dados obtidos, foram realizadas análises estatísticas individuais e conjunta dos anos, e as médias foram comparadas pelo teste de Tukey, a 5% de significância. As análises estatísticas foram realizadas utilizando o software R. Resultados mostraram que ‘Manchester’ sem enxertia, obteve maior produtividade, além de possuir menor custo da muda. A enxertia aumentou a firmeza da polpa do fruto que p... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Watermelon is a vegetable widely cultivated in Brazil, being consumed by all social classes. Grafting has been used for this crop in many countries and the benefits are soil-borne disease control, greater nutrient uptake, better efficiency in water use, increased tolerance to extreme temperatures, increased tolerance to salinity and flooding. Thus providing better yield and fruit quality. Considering the above, the performance of three rootstocks ('Strong Tosa', 'Super Shintosa' and 'Carnivor') with ‘Manchester’ F1 watermelon were evaluated. Experiments were grown in 2016 in the city of Holambra-SP and in 2017 in the cities of Itápolis-SP and Holambra-SP. Each experiment used a randomized complete block design with five treatments and four replications. Plant development, production and fruit quality traits were evaluated for all experiments, as well as nutrient content of the plant and fruit in the experiments carried out in Holambra-SP. From the data obtained, individual and conjoint statistical analyzes of the years were performed and the averages were compared by the Tukey test at the 5% level of significance. Statistical analyzes were carried out using software R. Results showed that the un-grafted ‘Manchester’ F1 obtained a higher yield plus had the lower transplant cost. Grafting increased the flesh firmness, which can be a benefit during the transport of the fruit. Plant development, fruit production and quality traits, were not generally affected by the use of grafti... (Complete abstract click electronic access below) / Doutor