This thesis exploits so called “Optical Eigenmodes” (OEi) in the focal plane of an optical system. The concept of OEi is introduced and the OEi operator approach is outlined, for which quadratic measures of the light field are expressed as real eigenvalues of an Hermitian operator. As an example, the latter is employed to locally minimise the width of a focal spot. The limitations of implementing these spots with state of the art spatial beam shaping technique are explored and a selected spot with a by 40 % decreased core width is used to confocally scan an in focus pair of holes, delivering a two-point resolution enhanced by a factor of 1.3. As a second application, OEi are utilised for fullfield imaging. Therefore they are projected onto an object and for each mode a complex coupling coefficient describing the light-sample interaction is determined. The superposition of the OEi weighted with these coefficients delivers an image of the object. Compared to a point-by-point scan of the sample with the same number of probes, i.e. scanning points, the OEi image features higher spatial resolution and localisation of object features, rendering OEi imaging a compressive imaging modality. With respect to a raster scan a compression by a factor four is achieved. Compared to ghost imaging as another fullfield imaging method, 2-3 orders of magnitude less probes are required to obtain similar images. The application of OEi for imaging in transmission as well as for fluorescence and (surface enhanced) Raman spectroscopy is demonstrated. Finally, the applicability of the OEi concept for the coherent control of nanostructures is shown. For this, OEi are generated with respect to elements on a nanostructure, such as nanoantennas or nanopads. The OEi can be superimposed in order to generate an illumination of choice, for example to address one or multiple nanoelements with a defined intensity. It is shown that, compared to addressing such elements just with a focussed beam, the OEi concept reduces illumination crosstalk in addressing individual nanoelements by up to 70 %. Furthermore, a fullfield aberration correction is inherent to experimentally determined OEi, hence enabling addressing of nanoelements through turbid media.

Les maladies pulmonaires tel que l’amiantose ou le mésotheliome proviennent de l‘interaction entre les fibres d’amiantes et les cellules humaines. L’hétérogénéité morphologique et chimique des fibres nous oblige à disposer de moyens analytique capable d’analyser l’interaction organique – inorganique. Nos travaux ont pour but de développer une méthodologie d'imagerie infrarouge couplé avec le rayonnement synchrotron. Grâce à cette technique, nous pourrons analyser les effets des fibres d'amiantes sur une cellule unique. La méthodologie a été testée sur des cellules cultivées directement sur des substrats transparents à l'infrarouge. Les expériences réalisées ont été étendu à l'imagerie Raman in vitro de cellule individuelle vivante en interaction avec différents types de fibres afin de mieux évaluer l'effet pathogène de celle ci sur les cellules pulmonaire. / Lung disease as asbestosis and mesothelioma come from the interaction between asbestos fibers and human cells. The morphological and chemical heterogeneity of these fibers leads us to use analytical techniques capable of analyzing the organic/inorganic interaction. Our work aims the development of FTIR method couple with the synchrotron radiation. Thanks to that technique, we could analyse the effects of the asbestos fibers on a lung human cell. These technique has been developped on cultured cells directly on IR transparent substrates. The experimentation have been developped to in vitro RAMAN imaging of individual living cell in interaction with different types of fibers. The goal was a better understanding of the pathological effect of the asbestos fibers on the human lung cells.

Ce travail présente l’optimisation d’un système de spectroscopie Raman résolue en temps dédiée aux très hautes températures. Ce dispositif répond au besoin sans cesse croissant d’étudier en temps réels les transformations de phases et des cinétiques de réactions dans des environnements extrêmes. Ce dispositif a été validé dans des conditions d’usages sur des oxydes (Gd₂O3, Y₂O3, ZrO₂ , ZrSiO4 et CeO₂) et des nitrures (h-BN). Le potentiel du système a permis de lever les principaux verrous technologiques et instrumentaux qui limitent l’utilisation de la spectroscopie Raman à haute température. Les trois principaux faits marquants qui illustrent le caractère innovant de ce travail sont les suivants : Le premier correspond au nouveau record mondial d’analyse Raman à haute température à travers l’acquisition du mode E₂g de h-BN jusqu’à 2700°C. La comparaison des performances des deux voies Pockels et ICCD montrent que la voie Pockels est plus performante que l’ICCD, mais plus délicate de mise en oeuvre. Le second fait marquant concerne les autres applications du Raman résolu en temps, comme pour séparer la contribution de la diffusion Raman et de la luminescence. La dernière application quant à elle présente l’étude de la dépendance temporelle comparée des diffusions Raman résonnante et non résonante. Le Raman résonnant se déclenche systématiquement avant le non résonnant. Plus généralement, l’intérêt des méthodes Raman résolues en temps ouvre de nouveaux champs d’application dans la caractérisation de matériaux en condition extrêmes, éventuellement in situ : aéronautique, réfractaire ; sidérurgie, nucléaire, etc… / This work presents the optimization of a time-resolved Raman spectroscopy device dedicated to very high temperatures. This device meets the ever-increasing need to study in real time phase transformations and reaction kinetics in extreme environments. This device has been validated under working conditions on oxides (Gd₂O3, Y₂O3, ZrO₂ , ZrSiO4 et CeO₂) and nitrides (h-BN). The potentialities of the device have enabled the main technological and instrumental locks that limit the use of high temperature Raman spectroscopy to be removed. The three main highlights illustrating the innovative nature of this work are as follows. The first corresponds to the new world record for high temperature Raman analysis through the acquisition of the E₂g mode of h-BN up to 2700°C.A comparison of the performance of the two Pockels and ICCD channels shows that the Pockels channel is more efficient than the ICCD, but more difficult to implement. The second important fact concerns the other applications of time-resolved Raman, as to separate the contribution of Raman scattering and luminescence. The last application presents the study of the comparative time dependence of resonant and non-resonant Raman scattering. The resonant Raman is triggered systematically before the non-resonant. More generally, the interest of time-resolved Raman methods opens new fields of application in the characterization of materials in extreme conditions, possibly in situ: aeronautics, refractories, steel industry, nuclear, etc....

La fonction barrière de la peau, qui protège l’organisme contre les molécules exogènes, limite la pénétration des actifs cosmétiques, ce qui réduit l’efficacité des molécules actives dans les couches profondes de l’épiderme. Il est alors apparu essentiel d'optimiser l'administration des actifs cosmétiques déjà existants afin d’en tirer tout le bénéfice escompté. Certaines innovations sont développées pour répondre à ce défi, notamment l’encapsulation des actifs cosmétiques dans des nanosystemes. En parallèle, il est nécessaire de s’intéresser aux méthodes analytiques capables de fournir une information qualitative et quantitative sur ces systèmes dispersés dans un produit fini complexe et de permettre une évaluation biologique à différents stades de développement des formulations. / The barrier function of the skin, which protects the body against exogenous molecules, limits the penetration of active cosmetic ingredients (ACI), thus reduce the effectiveness of molecules with a deep cellular target. Therefore, it appeared crucial to optimize the administration of existing active cosmetic in order to get the full benefits expected. Some innovations are explored to bypass this issue, including the encapsulation of existing active cosmetic in nanocarriers. In parallel, it is important to also focus on the development of analytical methodologies that could provide qualitative and quantitative information, in particular the determination of ACI contents and potentially excipients incorporated in a final form, and biological evaluation at different stages of formulation.

Ce travail s’inscrit dans le cadre général du développement de biomatériaux ostéoinducteurs pour la réparation de grands défauts osseux. L’étude est une contribution à la compréhension des interactions physiques et chimiques entre des céramiques phosphocalciques et deux protéines d’intérêt : la fibronectine, protéine d’adhésion cellulaire, et le VEGF (pour Vascular Endothelial Growth factor) qui est impliqué dans la vascularisation et l’amélioration de la formation osseuse.Les interactions physiques fibronectine/biocéramique ont été étudiées par spectroscopie de force afin d’évaluer l’influence de la topographie et de la composition chimique de céramiques phosphocalciques en hydroxyapatite (HA), hydroxyapatite silicatée (SiHA) et hydroxyapatite carbonatée (CHA) sur l’adhésion de la fibronectine. Les résultats obtenus par cartographie de forces mettent en évidence une absence d’incidence de la chimie des céramiques polies sur la répartition en surface et l’intensité des forces d’adhésion. En revanche ces dernières sont plus fortes au niveau des joints de grains des céramiques non polies mettant en avant une influence de la topographie de surface des matériaux modulée par la chimie.Le protocole de fonctionnalisation par le VEGF consiste en trois étapes : silanisation, addition du SM(PEG)6 et immobilisation du VEGF. Les interactions chimiques VEGF/biocéramique ont été étudiées principalement par imagerie Raman pour suivre ces étapes successives de la fonctionnalisation par le VEGF de céramiques polies en hydroxyapatite (HA) et hydroxyapatite carbonatée (CHA). Cette approche a permis de cartographier l’évolution chimique de la surface des matériaux et de mettre en évidence la distribution spatiale ainsi que les réactions préférentielles entre les molécules intermédiaires et le VEGF en fonction de la nature du substrat. / This work is ascribed within the framework of the development of osteoinductive biomaterials for the repair large bone defects. It is a contribution to the understanding of the physical and chemical interactions between phosphocalcic ceramics and two proteins of interest: fibronectin (Fn), a cell adhesion protein, and Vascular Endothelial Growth Factor (VEGF) which is involved in vascularisation and improvement of bone formation.Fibronectin/bioceramic physical interactions were studied by force spectroscopy to evaluate the influence of the topography and the chemical composition of phosphocalcic ceramics made of hydroxyapatite (HA), silicated hydroxyapatite (SiHA) and carbonated hydroxyapatite (CHA) on fibronectin adhesion. The results obtained in terms of force cartography do not indicate any impact of the polished ceramics chemistry on the surface distribution and intensity of adhesion forces. However, these forces are more intense at the level of the grain boundaries of unpolished ceramics, highlighting an influence of the topography modulated by the chemical composition.The protocol for functionalisation by VEGF consists of three steps: silanisation, addition of SM(PEG)6 and immobilisation of VEGF. VEGF/bioceramic chemical interactions were studied mainly by Raman imaging in order to follow the successive steps of the functionalisation by VEGF of the polished surface of ceramics made of hydroxyapatite (HA) and carbonated hydroxyapatite (CHA). This approach allowed to map the surface chemical changes and to point out the spatial distribution as well as the preferential reactions between the intermediate molecules and VEGF depending of the substrate.

No description available.

The CdTe family members (in particular CdZnTe) remain the substrate of choice for epitaxial growth of HgCdTe for use in high performance infrared (IR) detectors and focal plane arrays. This is the case despite advances in the use of alternate substrate technologies such as buffered GaAs and GaAs on Si; these technologies, to date, have not reproducibly demonstrated device performance comparable to the arrays made in HgCdTe grown on CdZnTe and CdTe. The quality of CdTe family materials has improved significantly over the past several years and so the quality and reproducibility of IR detectors has improved along with them. It is clear, however, that CdTe family substrates still have a significant impact on the performance of HgCdTe devices and that further research is required to reduce the effects of substrate on these devices. Unlike silicon or gallium arsenide, it is very difficult to grow the large area single crystals of CdZnTe due to thermodynamic limitations. It has the lowest thermal conductivity among all semiconductors that makes it difficult to obtain planar solid-liquid interface, which is desirable for the growth of large area single crystals of CdZnTe. Due to its high ionicity and weak bonding, defects are easily incorporated during the growth. Also, it is well established that both the structural defects and impurity content of Hg1-xCdxTe epitaxial layers are strongly influenced by the quality of the substrates used in the epitaxial growth process. A substrate of poor structural quality will result in a poor substrate/layer interface from which defects will propagate into the epilayer. It is known that our focal plane arrays (FPAs) are backside illuminated, with the device connected to underlying silicon multiplexer, using a matrix of indium bumps. Thus the substrate should have high IR transmission to pass the radiation on to the detector for collection. High IR transmission requires chemically and electrically homogeneous crystals free from extraneous second phase particles. This objective is one of the most difficult thermodynamic and technological problems in the growth of CdTe and related alloys. The bulk CdZnTe crystals grown from melt suffer from the inherent disadvantage of accommodating tellurium precipitates because of high growth temperature and phase diagram limitations. These tellurium (Te) precipitates condense as cadmium vacancies and Te interstitials during the cooling process, which contribute to intrinsic point defects. Although extensive efforts have been made in the area of purification of the CdZnTe crystals by using 6N pure starting materials, still the high temperature melt growth leads to impurity pickup during the crystal growth process. This deviation in the stoichiometry, especially due to free carriers, impurities and second phase tellurium precipitates, play the major role in reducing the infrared transmission through the CdZnTe substrate material. Also they affect the device performance when used for detector applications. In this context a thorough investigation of the non-stoichiometry of the CdZnTe material is mandatory to improve the material quality. It is my endeavor in this respect to present in this thesis “optical and structural investigations of defects in CdZnTe (Zn~4%) crystals”. The present thesis has been organized into six chapters. Chapter 1: It presents an up to date comprehensive review of the defects in CdTe binary and CdZnTe ternary compound semiconductors. It includes an introduction to the ternary II-VI cadmium zinc telluride with potential device applications. Issues related to CdTe based substrates for infrared (IR) applications have been discussed. Growth as well as several material aspects like crystal structure, band structure, mechanical, thermal, optical and dielectric properties have been discussed in details. The chapter ends with the motivation and scope for the present thesis. Chapter 2 : Te precipitates were identified and characterized in CdZnTe (Zn ~ 4%) crystals using various physical characterization techniques and the results are presented in Chapter 2. X-ray diffraction rocking curve measurements were carried out on a series of samples to assess the overall crystalline quality of the as grown CdZnTe crystals, in conjunction with Fourier transform infrared (FTIR) absorption spectroscopy measurements to identify the presence of Te precipitates. Further, the CdZnTe samples having Te precipitates were systematically characterized using micro-Raman imaging technique. CdZnTe wafers grown in three and six zone furnaces using quartz and/or pyrolytic boron nitride (PBN) crucibles have been subjected to micro-Raman imaging to quantify and understand the nature of Te precipitates. It is well known that for the normal phase of Te precipitates, the Raman modes appear centered around 121 (A1), 141(E) /TO (CdTe) cm -1and a weak mode around 92 (E) cm -1 in CdZnTe indicating the presence of trigonal lattice of Te. Using the micro-Raman maps and taking the spatial distribution of the area ratio of 121 to 141 cm-1 Raman modes, the size and distribution of Te precipitates were estimated. A substantial reduction in Te precipitate size and an improvement in the IR transmission in the 2.2 – 5 µm IR window was observed in the CdZnTe crystals subjected to post growth annealing under Cd+Zn vapors at 650 oC for 6 hrs. Also it is shown that the samples grown in pyrolytic boron nitride (PBN) crucibles have shown an overall improvement in the crystalline quality and reduction in the Te precipitate size as compared to the samples grown in quartz crucibles. The possible reasons for these observations have been discussed in chapter 2. The presence of Te precipitates under high pressure phase was detected by the blueshift of the Raman bands that appear at 121 (A1) cm-1for a normal Te phase, indicating that these micro-Raman maps are basically the distribution of Te precipitates in different phases. NIR microscopy imaging has been carried out to further substantiate the presence of Te precipitates under high pressure phase and that of larger Te precipitates. The significance of micro-Raman imaging lies in quantifying and demonstrating the high pressure phase of Te precipitates in CdZnTe crystals in a non-destructive way. Also it is shown that the presence of Te precipitates lead to loss of useful signal in the 2.2 – 6 µm wavelength regions and hence are “deleterious” for substrate applications of CdZnTe crystals required for the growth and fabrication of HgCdTe detectors. Chapter 3: The effects of annealing and hydrogenation on the low temperature photoluminescence (PL) spectra of CdZnTe (Zn ~ 4%) crystals are reported in this chapter. It is shown that annealing at 600 oC for 12 hrs under Cd vapors has resulted in the disappearance of both C-A and DAP recombination features (attributed to singly ionized cadmium vacancy acceptors) observed in the 1.5 – 1.6 eV band edge region in the low temperature PL spectra of CdZnTe, confirming the origination of these bands from Cd vacancy defects. The presence of copper impurity has been identified by the appearance of the 1.616 (AoX) eV energy peak attributed to exciton bound to the neutral copper acceptor and the 1.469 eV band attributed to copper acceptor in the donor acceptor pair (DAP) recombinations. It is shown that, only annealing under Cd+Zn vapors at 650 oC for 6 hrs has resulted in the passivation of the 1.469 eV band and the mechanism has been explained invoking the Hume-Rothery rule. Passivation of the 1.469 eV band is significant, since CdZnTe substrate copper contamination was found to degrade HgCdTe epitaxial layer and hence the performance of HgCdTe infrared (IR) detectors. Also it shown that vacuum annealing has resulted in the introduction of a new defect band around 0.85 eV in the low temperature PL spectra of CdZnTe possibly due to the loss of Cd and/or Zn. Further, the effects of hydrogenation in passivating the defect bands observed in the low temperature PL spectra of the control CdZnTe crystals are discussed. Using micro-Raman imaging technique, it is shown that hydrogenation has resulted in the reduction in size and restoration of normal phase for Te precipitates, which otherwise were present under high pressure phase in CdZnTe crystals. It is shown that the net effect of hydrogenation is to improve the quality of CdZnTe crystals at low temperature (50 oC) as compared to the high Cd+Zn annealing temperature (650 oC) whose effect is only to reduce the size of Te precipitates. To further substantiate this an analysis of the temperature dependent resonance micro-Raman spectra recorded with 633 and 488 nm lasers has been made and it is shown that appearance of the multiple orders (up to 4 orders) of the CdTe like LO phonon modes and emergence of the ZnTe like LO phonon mode are clear indications of the improved quality of the hydrogenated CdZnTe crystals. Chapter 4: Manifestation of Fe2+and Fe3+charge states of Fe in undoped CdZnTe (Zn ~ 4 %) crystals grown in quartz crucibles by asymmetrical Bridgemann method and their respective optical and magnetic behaviors have been discussed in this chapter. Fe2+being optically active shows absorption around 2295 cm-1in the low temperature (T = 3 K) FTIR spectra, while Fe3+being magnetically active exhibits coexistence of para and ferromagnetic phases, as identified by low temperature electron spin resonance and supported independently by low temperature SQUID and AC susceptibility measurements. In the paramagnetic phase (TC ~ 4.8 K) the inverse of ac susceptibility follows the Curie-Weiss law. In the ferromagnetic phase (TC ~ 4.8 K) the thermal evolution of magnetization follows the well known Bloch’s T3/2 law. This is further supported by the appearance of hysteresis in the SQUID measurements at 2K below TC. Small coercive field of 10 Oe as estimated in the hysteresis suggests that the magnetic anisotropy is very small in these systems. Chapter 5: In this chapter, details of the indigenously developed laser beam induced current (LBIC) instrumentation have been presented. These include instrumental arrangement of the micro-mechanical system for raster scanning of defects in semicoductors and fabrication details of continuous flow liquid helium cryostat for low temperature LBIC measurements. Preliminary LBIC data recorded using this system have been shown to demonstrate the operability of the system. Chapter 6: This chapter includes a brief write-up summarizing the results and draws the attention for the possible future work. Appendix A: Here C++ programs for LBIC measurements are presented. Appendix B: Here the CAD diagrams for the full cross sectional view of the liquid helium cryostat consisting of “assembly liquid helium cryostat” and “part liquid helium cryostat” are attached.

Les piles à combustible (PAC) utilisant l’hydrogène comme vecteur, possèdent de bons rendements énergétiques et ne produisent aucun gaz à effet de serre. Elles se présentent donc aujourd’hui comme une solution propre et efficace. Cette alternative pourrait ainsi devenir un substitut possible aux hydrocarbures et pallier l’intermittence de certaines énergies renouvelables.Il existe différents types de PAC se distinguant principalement par la nature de l’électrolyte qui compose leur membrane échangeuse de protons. Utiliser les clathratehydrates d’acide fort comme électrolyte solide représente une alternative peu explorée à ce jour. Ces systèmes sont des solides cristallins nanoporeux constitués d’un réseau hôte de molécules d’eau formant des cavités nanométriques et encapsulant des molécules invitées.Dans le cas de clathrate hydrates d’acide fort, le confinement d’acides au sein des cages aqueuses génère des excès de protons délocalisés le long de leur réseau aqueux. A température ambiante, ces clathrate hydrates présentent alors une excellente conductivité protonique, plus élevée que celle des membranes de PACs actuellement utilisées. L’objectif de ce doctorat a été d’élaborer un électrolyte à base de clathrate hydrate d’acide hexafluorophosphorique (un des meilleurs conducteurs connus de cette classe de systèmes)sur la base d’une approche physico-chimique fondamentale, et de développer un montage miniaturisé de PAC intégrant ce nouvel électrolyte.A un niveau fondamental, il a été nécessaire de comprendre les facteurs régissant la conductivité protonique élevée de ces systèmes et en particulier, le lien existant entre la conductivité et le nombre d’hydratation (rapport molaire eau/acide dans le clathrate). Les mécanismes microscopiques mis en jeu ont été étudiés en s’appuyant sur la spectroscopie et l’imagerie Raman, complétées par des expériences de résonance magnétique nucléaire, de diffraction des rayons X et de spectroscopie d’impédance électrochimique. Un ensemble d’informations structurales (type de clathrate formé, transition de phase et stabilité thermodynamique), dynamiques (modes de vibration, diffusion des protons et cinétique) et chimiques (inclusion d’impuretés fluorées) a ainsi été obtenu. En tant que sonde sélective et locale, la technique de diffusion Raman a apporté des informations uniques. Elle a permis de sonder les interactions acides-cages, de proposer un protocole expérimental permettant de contrôler le nombre d’hydratation et également, de révéler pour la première fois une microstructuration du clathrate hydrate observée uniquement au-dessus d’un seuil d’hydratation. Ces propriétés physico-chimiques ont été corrélées aux mesures de conductivité, permettant de comprendre l’impact du nombre d’hydratation et des impuretés chimiques sur les performances de l’électrolyte solide. L’ensemble de ces résultats a permis d’aboutir à un développement technologique original. Une nouvelle micropile à combustible utilisant des clathrate hydrates d’acide hexafluorophosphorique comme électrolyte a été conçue. Ce développement offre ainsi une PAC aux performances comparables aux PACs actuellement disponibles et fonctionnant de la température ambiante à des températures négatives. / Fuel cells (FC) using hydrogen possess very good energy performance and produce no greenhouse gases. It presents itself today as a clean and efficient solution. This alternative could then become a possible substitute for fossil fuels and palliate for the intermittency ofcertain renewable energies.There are various types of FC, mainly distinguished by the nature of the electrolyte that composes their proton exchange membrane. Using strong acid clathrate hydrates as solid electrolyte represents an alternative for which very little is known nowadays. These systems are nanoporous crystalline solids consisting of a water host network forming nanometric cavities encapsulating guest molecules. In the case of strong acid clathrate hydrates, the confinement of acidic species within the aqueous cages generates proton excess that isdelocalized along their aqueous network. At room temperature, these clathrate hydrates have then excellent proton conductivity, which is higher than that of the FCs membranes currently used. The objective of this PhD was to develop an electrolyte based on hexafluorophosphoricacid clathrate hydrate (one of the best-known conductors of this class of system) on the basisof a fundamental physico-chemical approach, and to develop a miniaturized FC assemblyincorporating this new electrolyte.At a fundamental level, it was necessary to understand the driving factors responsible for the super-protonic conductivity of these systems and in particular, the relationship between the conductivity and the hydration number (i.e. water to acid molar ratio in the clathrate). The microscopic mechanisms have been studied by means of Raman spectroscopy and imaging, supplemented by nuclear magnetic resonance, X-ray diffraction and electrochemical impedance spectroscopy experiments. A set of results concerning the structure (clathrate type, phase transition and thermodynamic stability), the dynamics (vibrational modes, proton diffusion and kinetics) and the chemistry (inclusion of fluorinated impurities) has thus been obtained. As a selective and microscopic probe, the Raman scattering technique provided unique information. It allowed to probe the acid-cages interactions, to propose an experimental protocol monitoring the hydration number and also,to reveal, for the first time, a microstructuration of the clathrate hydrate only observed abovea hydration threshold. These physico-chemical properties have been correlated with the conductivity measurements, making it possible to understand the impact of the hydration number and of the chemical impurities onto the electrochemical performances of the solid electrolyte. All these results led to an original technological development. A new micro-fuel cell using hexafluorophosphoric acid hydrates as the electrolyte has been designed. This development offers a FC with performances comparable to the FCs currently available and operating from room temperature to negative temperatures.