Nous couplons des sources de rayonnement infrarouge et un spectromètre à transformée de Fourier (FTIR) avec un microscope optique en champ proche (SNOM) à pointe diffusante pour sonder les propriétés optiques locales de la matière avec une résolution spatiale sub-longueur d'onde.Nous étudions l'émission thermique de champ proche d'un échantillon constitué d'une couche d'or recouvrant partiellement du carbure de silicium, puis d'un empilement de nano-couches semi-conductrices. Nous révélons expérimentalement la présence d'ondes de surface se propageant aux différentes interfaces de ces échantillons, en imagerie et en spectroscopie. Nous sondons l'évolution spatiale du spectre de la densité locale d'états électromagnétiques grâce à l'imagerie hyperspectrale super-résolue de l'émission thermique de champ proche. Nous montrons que la résolution spatiale et le contraste entre les structures diminuent lorsque la distance à laquelle la sonde effectue les balayages augmente.Nous couplons notre SNOM et un FTIR avec le rayonnement synchrotron et démontrons la capacité d'un tel couplage de mener des études de nanospectroscopie dans l'infrarouge moyen en l'illustrant sur les échantillons précédemment mentionnés. Nous démontrons l'imagerie térahertz super-résolue à l'aide du rayonnement synchrotron.Nous étudions expérimentalement l'influence de l'illumination sur les images obtenues en SNOM et montrons que la détection de l'émission thermique de champ proche permet d'obtenir des images exemptes de distorsions et donc plus simples à interpréter que celles obtenues en utilisant un laser monochromatique ou l'émission thermique de champ lointain. Nous développons un mode d'imagerie 3D. / We couple infrared sources with a scattering near-field scanning optical microscope (SNOM) combined with a Fourier transform infrared spectrometer (FTIR) in order to probe the local optical properties of matter with sub-wavelength spatial resolution. We study the near-field thermal emission of a surface made of silicon carbide and gold, and then of a semiconductor-based multilayer. We reveal experimentally the presence of surface waves propagating at the different interfaces of these samples, by imaging and spectroscopy. We probe the spatial evolution of the electromagnetic local density of states spectrum thanks to super-resolved hyperspectral imaging of the near-field thermal emission. We show that spatial resolution and contrast between the structures decrease as the distance at which the probe performs the scans increases. We couple our SNOM and FTIR with synchrotron radiation and demonstrate the capability of such coupling to perform nanospectroscopy studies in the mid-infrared range by investigating the samples mentioned above. We demonstrate super-resolved terahertz imaging using synchrotron radiation. We experimentally study the influence of the illumination on the images obtained in SNOM and show that the detection of the near-field thermal emission provides distortion-free images and therefore are easier to interpret than those obtained using a monochromatic laser source or far-field thermal emission. We also develop a 3D imaging technique.

An increase in the number of debris-covered glaciers and expansion of debris cover across many glaciers has been documented in many of the world’s major glacierised mountain ranges over the last 100 years. Debris cover has a profound impact on glacier mass balance with thick layers insulating the underlying ice and dramatically reducing ablation, while thin or patchy cover accelerates ablation through albedo reduction. Few debris-covered glaciers have been studied in comparison with ‘clean’ glaciers and their response to climatic change is uncertain. Remote sensing, integrated with field data, offers a powerful but as yet unrealised tool for studying and monitoring changes in debris-covered glaciers. Hence, this thesis focuses on two key aims: i) to test the utility of visible/near infrared satellite sensors, such as TERRA ASTER, for studying debris-covered glaciers; ii) to develop techniques to fully exploit the capability of these satellite sensors to extract useful information, and monitor changes over time. Research was focused on four interrelated studies at the Miage Glacier, in the Italian Alps. First, a new method of extracting debris-thickness patterns from ASTER thermal-band imagery was developed, based on a physical energy-balance model for a debris surface. The method was found to be more accurate than previous empirical approaches, when compared with field thickness measurements, and has the potential advantage of transferability to other sites. The high spatial variability of 2 m air temperature, which does not conform to a standard lapse rate, presents a difficulty for this approach and was identified as an important area for future research. Secondly, ASTER and Landsat TM data are used to map debris-cover extent and its change over time using several different methods. A number of problems were encountered in mapping debris extent including cloud cover and snow confusion, spatial resolution, and identifying the boundary between continuous and sporadic debris. Analysis of two images in late summer 1990 and 2004 revealed only a small up glacier increase in debris cover has occurred, confirming other work’s conclusions that the debris cover on Miage Glacier increased to its present extent prior to the 1990s. A third area of research used ASTER DEMs to monitor surface elevation changes of the Miage Glacier over time to update previous studies. Surface velocities on the glacier tongue were also calculated between 2004-2005 using feature-tracking of ASTER orthorectified visible band imagery and ASTER DEMs. However, ASTER DEMs were found to be rather poor for both applications due to large elevation errors in topographically rough parts of the glacier, which prevented a full analysis and comparison of results to previous surface elevation and velocity studies. Finally, the lithological units of the debris cover were mapped, based on the spectral differences of different rock types in the debris layer, providing information both on the location and concentration of different rock types on the surface. Therefore, the identification in the variation in emissivity throughout the glacier surface can be identified, which in turn has an impact upon calculated surface temperatures and ablation respectively. Overall, this research presents a significant contribution to understanding the impact of a debris layer on an alpine glacier, which is an area of key interest and current focus of many present glaciological studies. Since future glacial monitoring will increasingly have to consider supraglacial debris cover as a common occurrence, due to climate warming impacts of glacial retreat and permafrost melting. This contribution is achieved through the successful application of methods which utilise ASTER data to estimate debris thickness and debris extent, and the lithological mapping of debris cover. Therefore, the potential for incorporating these remote sensing techniques for debris-covered glaciers into current global glacier monitoring programs has been highlighted. However the utility of ASTER derived DEMs for surface elevation change analysis and surface velocity estimations in a study site of steep and varied terrain has been identified as questionable, due to issues of ASTER DEM accuracy in these regions.

La miniaturisation des transistors atteignant aujourd’hui des tailles de l’ordrede la dizaine de nanomètres a introduit des problèmes de contrôle de la chaleuraux courtes échelles. Ce défi industriel, parmi d’autres, a permis l’émergencede l’étude des transferts thermiques à l’échelle nanométrique. Un des axes derecherche de cette thématique concerne le rayonnement de champ proche. Ils’agit de comprendre le comportement des ondes thermiques sur des distancesinférieures à leur longueur d’onde. A cette échelle les ondes contenant la densitéénergétique la plus importante sont des ondes évanescentes, confinées ensurface. Le phonon-polariton de surface (PPS) en est un type : c’est une ondeévanescente se propageant à la surface de matériaux polaires et diélectriques.L’objectif de ce travail de thèse est d’examiner la propagation de PPS le longde la surface de tubes de verre micrométriques, et de montrer en quoi cettegéométrie favorise le transfert de chaleur par le biais de ces ondes.Une étude théorique a été menée pour justifier l’utilisation de ce guide d’ondesde chaleur dont la conductivité thermique peut être jusqu’à doublée grâce auxPPS. La présence des PPS est ensuite détectée expérimentalement. En effetla diffraction de ces ondes à la pointe du tube est décelée par un ensemblemicroscope-spectromètre à transformée de Fourier IR. Le spectre du rayonnementobtenu prouve la diffraction de PPS grâce à leurs signatures spectralesspécifiques. / Miniaturization of transistors, whose sizes reach a few tens of nanometers nowadays,implies new problems of heat control at very short scales. This big challenge among others enabled the emergence of nanoscale heat transfer as a new research domain. Near-field heat transfer is one of the axis of this thematic.It concerns the behavior of thermal waves at a scale shorter than their wave lengths.Under these conditions the waves with the highest energy density are evanescent, that is confined at the surface. Surface phonon-polariton (SPhP) is a particular case of an evanescent wave propagating at the surface of a polar dielectric material. This PhD work consists in examining SPhP propagation along the surface of micrometric glass tubes and in proving the ability of these waves to enhance heat transfer in these systems.A theoretical analysis has been carried out to justify the use of such heat waveguides whose thermal conductivity can be doubled due to SPhP. The experimental detection of those waves based on their diffraction at the tip of the glass tubes is then presented. This emission is measured thanks to the assembly of a microscope and a Fourier-transform IR spectrometer. The presence of SPhPs is proved through measured spectra exhibiting their characteristic spectral signature.

Cette thèse porte sur la modélisation théorique de l'équation d’état (EE) décrivant la matière nucléaire présente dans le coeur des étoiles à neutrons (EN), sous l'hypothèse qu'aucune transition de phase ne s'y produise. Nous utilisons un méta-modèle permettant i) d’incorporer directement les connaissances en physique nucléaire sous la forme de paramètres empiriques tels que la densité de saturation nucléaire, l’incompressibilité, l’énergie de symétrie; ii) de reproduire la plupart des modèles nucléoniques existants; et iii) d’explorer les régions inconnues à haute densité de façon la plus large possible. Pour chaque EE, nous déterminons un ensemble de solutions pour la masse et le rayon des EN, et nous effectuons une première sélection des EE compatibles avec la stabilité et la causalité de la matière nucléaire, ainsi que la masse maximale connues des EN. Nous confrontons ensuite ces EE aux observations d’émission thermique dans la gamme des rayons-X pour 7 EN soigneusement choisies. Pour la première fois, la modélisation théorique des EE est directement introduite dans l’analyse des données. Nous utilisons les dernières mesures effectuées par GAIA II pour fixer la distance des EN. Les paramètres du modèle d’émission thermique et de l’EE sont déterminés selon une méthode Bayésienne basée sur un algorithme Monte-Carlo par Chaîne de Markov. Nous déterminons ainsi la température de surface, la masse et le rayon des EN, ainsi que sur la valeur de certains paramètres empiriques tels que la dépendance en densité de l'énergie de symétrie (Lsym), la contribution isovectorielle au module d’incompressibilité (Ksym) ou encore le paramètre de distorsion isoscalaire (Qsat) / This thesis concerns theoretical modeling of the equation of state (EoS) describing nuclear matter in the core of neutron stars (NS), under the hypothesis that no phase transition occurs. We use a meta-model which is able to i) directly incorporate nuclear physics knowledge on the form of empirical parameters such as the nuclear saturation density, the incompressibility or the symmetry energy; ii) reproduce most of the existing models; iii) explore new behaviors at high densities in a very flexible way. For each EoS, we determine a set of solutions for the masses and radii of NS, and we make a first selection of the EoS that are compatible with the stability and causality constraints, as well as the maximum observed mass of NS. Then we confront these EoS to observational data coming from thermal emission in the soft X-ray domain, for 7 NS carefully chosen. For the first time, the theoretical modeling of the EoS is directly implemented in the data analysis. We use the recent measurments of GAIA II to constrain the distance to the NS. The parameters of the modeling of thermal emission as well as the empirical parameters entering in the EoS are determined by Bayesian methods using a Monte-Carlo by Morkov Chain algorithm. Therefore, we determine the surface effective tempreature, the masses and radii of NS, as well as some empirical nuclear parameters such as the density dependance of the symmetry energy (Lsym), the isovector incompressibility (Ksym), or the isoscalar squewness (Qsat)