La compréhension des processus amenant à la formation d'étoiles depuis la phase dense du milieu interstellaire est possible via l'observation des molécules. Celles--ci nous permettent de contraindre, par l'intermédiaire d'une modélisation de leur émission, les conditions physiques, dynamiques et chimiques présentes dans les nuages au cours des différents stades de l'effondrement. Les milieux sondés lors de ce type d'étude correspondent, pour la plupart des molécules, à des conditions pour lesquelles le peuplement des niveaux d'énergie s'effectue hors équilibre thermodynamique. L'analyse du rayonnement nécessite alors des données de physique microscopique dont la précision influence fortement la description des régions modélisées. C'est dans ce contexte que s'inscrit le travail effectué durant cette thèse: celui-ci a porté, d'une part, sur la détermination de constantes de vitesses de collision pour les molécules N2H+ et H2O et d'autre part, sur l'interprétation de spectres observés pour ces molécules dans des régions de formation d'étoiles. La première de ces molécules, N2H+, constitue un excellent traceur des régions denses des nuages froids et la seconde, H2O, est la troisième espèce moléculaire la plus abondante dans les régions de formation d'étoiles massives ou de faibles masses et constituera le principal objectif du satellite Herschel. Pour la molécule N2H+, des constantes de vitesse de collision concernant la structure hyperfine ont été obtenues pour les niveaux hyperfins associés aux 7 premiers niveaux rotationnels et pour la gamme de température T=5-50 K. Pour cela, la dynamique collisionnelle a été etudiée avec une approche quantique indépendante du temps où la structure hyperfine est introduite via une méthode de recouplage. Ces données ont ensuite été utilisées afin d'interpréter l'émission observée dans un échantillon de nuages pré-protostellaires. En particulier, différentes approches ont été envisagées afin de traiter la résolution des équations d'équilibre statistique ce qui a permis de dégager les influences respectives qu'ont les taux de collision, le couplage radiatif et la structure en densité et température de la source sur les rapports d'intensité des transitions hyperfines associées à la transition j=1-0. Concernant H2O, l'objectif de ce travail est d'une part, de réactualiser les constantes de vitesse de collision du système H2O-H2, en se basant sur une surface d'énergie potentielle (SEP) récemment calculée et dont la précision est supérieure à celle qui a précédemment été utilisée. Ceci a tout d'abord permis une comparaison visant à établir la sensibilité des constantes de vitesse de collision à différents paramètres de la SEP. Ensuite, nous nous sommes intéressés à la détermination des paramètres d'élargissement de raies par collisions, en se basant sur l'approximation d'impact. L'intérêt de cette dernière étude est double: d'une part, ces données sont nécessaires à l'étude des atmosphères planétaires et d'autre part, par l'intermédiaire d'une confrontation entre résultats théoriques et données expérimentales, celle--ci nous donne une estimation de la qualité de la SEP et des données qui en sont issues. Finalement, en parallèle à ce travail, il a été effectué une analyse de l'émission de H2O observée dans la nébuleuse de Kleimann-Low dans Orion. A partir de données obtenues avec le satellite ISO, il a alors été possible de contraindre les conditions physiques de la source ainsi que la répartition spatiale de l'abondance de l'eau.

<p>In this thesis, volumetric, optical and vibrational properties of H₂O were studied at high pressures by combining techniques of Raman spectroscopy, interferometry and optical imaging. Pressures up to 7 GPa were generated in the diamond anvil cell (DAC), entering the stability fields of liquid water and ices VI, VII and VIII. </p><p>A new integrated system for Raman, interferometric and optical-imaging studies has been built up. Utilizing the interferometric patterns formed between closely-spaced diamond anvils, the system allowed the complete monitoring and control of <i>pVT</i>-conditions of studied ices, as well as the determination of their dispersive properties in the visible range using the Airy equation and Cauchy formulation. This setup and technique thus represent a novel tool for the precise determination of equations of state (EOSs) of transparent materials, including fluids and low-Z materials. </p><p>Data-sets on thermal pressure were obtained from heating/cooling experiments carried out on the liquid water and used for checking the mutual consistency between published EOSs. A <i>pVT</i>-EOS for ice VIII and room temperature isotherms for ices VI and VII at 300 K were derived by combined methods of interferometry and imaging. While the agreement with the available EOSs of ices VII and VIII is very good, some inconsistent EOSs of ice VI were identified in the present study.</p><p>The technique of micro-Raman spectroscopy was applied for the monitoring of phase transformations, identification of various ice phases and for studying the response of vibrational symmetry modes to varying conditions. Analysis based on the combination of the <i>pT</i>-dependencies of the vibrational frequencies with the <i>pVT</i>-EOSs showed that, in the studied ices, the implicit volume-driven contributions dominate over the explicit phonon effects in the total temperature-induced changes in vibrational frequencies. The results provide valuable insight on the anharmonic effects and interactions in these molecular solids.</p>

In this thesis, volumetric, optical and vibrational properties of H2O were studied at high pressures by combining techniques of Raman spectroscopy, interferometry and optical imaging. Pressures up to 7 GPa were generated in the diamond anvil cell (DAC), entering the stability fields of liquid water and ices VI, VII and VIII. A new integrated system for Raman, interferometric and optical-imaging studies has been built up. Utilizing the interferometric patterns formed between closely-spaced diamond anvils, the system allowed the complete monitoring and control of pVT-conditions of studied ices, as well as the determination of their dispersive properties in the visible range using the Airy equation and Cauchy formulation. This setup and technique thus represent a novel tool for the precise determination of equations of state (EOSs) of transparent materials, including fluids and low-Z materials. Data-sets on thermal pressure were obtained from heating/cooling experiments carried out on the liquid water and used for checking the mutual consistency between published EOSs. A pVT-EOS for ice VIII and room temperature isotherms for ices VI and VII at 300 K were derived by combined methods of interferometry and imaging. While the agreement with the available EOSs of ices VII and VIII is very good, some inconsistent EOSs of ice VI were identified in the present study. The technique of micro-Raman spectroscopy was applied for the monitoring of phase transformations, identification of various ice phases and for studying the response of vibrational symmetry modes to varying conditions. Analysis based on the combination of the pT-dependencies of the vibrational frequencies with the pVT-EOSs showed that, in the studied ices, the implicit volume-driven contributions dominate over the explicit phonon effects in the total temperature-induced changes in vibrational frequencies. The results provide valuable insight on the anharmonic effects and interactions in these molecular solids.

ON A ETUDIE LES EQUILIBRES ENTRE DES SOLUTIONS AQUEUSES CHLORUREES OU NON ET DES MINERAUX DU SYSTEME SIO::(2)-AL::(2)O::(3)-NA::(2)O-K::(2)O. LES DONNEES THERMODYNAMIQUES SUR LES PHASES SOLIDES ET LA DISTRIBUTION DES ESPECES ALCALINES ENTRE IONS ET MOLECULES DANS LES SOLUTIONS CONCENTREES DE CHLORURES DE SODIUM ET DE POTASSIUM SONT L'OBJET DE LA PREMIERE PARTIE; LA SECONDE PARTIE TRAITE DE L'IMPORTANCE DES COMPLEXES QUE LES ALCALINS FORMENT AVEC LA SILICE ET SURTOUT L'ALUMINE DANS LE SYSTEME ETUDIE

The solvent-solute interface of a biomolecule is a dynamic but yet highly structured domain that links a chemically diverse solute surface to the chemically homogeneous bulk aqueous phase. The role of the resulting intermediate domain, i.e. the "hydration shell", in regulating DNA structure and recognition has been addressed here by time-resolved infrared spectroscopy. A highly reproducible automated hydration pulse regime was established and implemented for attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy to monitor the structural response of DNA to an incremental growth of its hydration shell on its intrinsic time scale of seconds. The transition from the crystallographically defined BI to the BII substate of B-DNA was found to be driven by the increase of water disorder upon growth of the hydration shell, derived from the water OH-stretching absorption frequency and band width changes. 2D correlation analysis was used to identify different water clusters from the temporal behaviour of their water OH stretching frequencies. The results show that BII-stabilizing structural constraints are exerted by strong water-DNA H-bonds in the grooves of B-DNA and are relieved when the groove-bound water merges into a contiguous hydration shell with the less H-bonded PO2- -solvation sphere at ~14 water molecules per DNA phosphate. The H-bond imbalance at the disjunct hydration sites is split symmetrically around the average H-bond strength of bulk water. Thus, merging into a contiguous hydration shell proceeds at little enthalpic cost and homogeneous connectivity to the outer bulk-like H-bond network, such that alteration in the network distant from the DNA can regulate the BI-BII transition in a cooperative manner. The water connectivity is disrupted by DNA-binding peptides. Remarkably, the data show that the replacement of hydration shell water upon ligand biding is crucial in conferring substate specific recognition by peptides that have little intrinsic structural preference. The antibacterial peptide indolicidin secreted from bovine neutrophils dehydrates the non-PO2--bound hydration sites, thereby rendering the unstructured peptide highly specific for the BI state with vibrational signature almost identical to the bacterial minor groove binder netropsin. The proposed dominant role of hydration shell water for DNA conformation was challenged by studying the competing effect of structured water in the coordination-shell of the lanthanide Eu3+ on water structure in the DNA hydration shell. Whereas no effect is seen at low hydration, a hydrogen-like phase is formed at a stoichiometric ratio of Eu3+ :DNA:H2O of 1:10:140, characterized by a strong increase of the molar volume of hydration water. This novel phase appears attractive for lanthanide and possibly actine separation approaches based on biomolecular coordination.

Le travail que j’ai effectué durant ce doctorat est dédié à l’utilisation de l’ultrason des lasers sous haute pression physique. La recherche est construite en utilisant les récentes techniques de mesure de laser ultrasonique dans une enclume de diamant, conduisant à l’exploration de la propagation du son et de sa détermination suivant la vitesse de l’onde acoustique sous ultra-hautes pressions. La diffusion Brillouin a été appliquée ici pour déterminer l’épaisseur de la glace polycristalline compressée dans l’enclume à diamant sous pressions de mégabars. La technique permet d’examiner les caractéristiques des dimensions des inhomogénéités élastiques et la texture de la glace polycristalline, de ce fait ce processus est commun pour les surfaces de l’enclume à diamant avec des sous micromètres de résolution spatiale via les mesures des variations résolues dans le temps sur la vitesse de propagation du pouls acoustique voyageant dans l’échantillon compressé. Ceci a été appliqué pour mesurer la vitesse acoustique dans du H2O à l’état de glace jusqu’à 84 Gpa. La technique d’imagerie développée contient, pour chaque cristallite (ou groupe de cristallites) dans un ensemble homogène chimique transparent, des informations utiles sur son orientation ainsi que sur sa valeur élastique modulée par rapport à la direction de la propagation du son. Cela répand les bases pour une application réussite sur la déformation de solides sous haut-développement de modèles micromécaniques sous la pression à mégabars. Pour une plus longue durée, ce genre d’expériences répandus sur les minéraux de la terre et avec des températures basses ou hautes, assurerait un progrès important dans la compréhension de la construction de la cape terrestre, son évolution ainsi que celle d’autres planètes. / This PhD research work is devoted to the use of laser ultrasound in high-pressure physics. The research is done using the recently established technique of laser ultrasonic measurements in a diamond anvil cell which allows investigation of the sound propagation and determination of the acoustic wave velocities at ultrahigh pressures. Time domain Brillouin scattering was applied here to depth-profiling of polycrystalline aggregate of ice compressed in a diamond anvil cell to megabar pressures. The technique allowed examination of characteristic dimensions of elastic inhomogeneities and texturing of polycrystalline ice in the direction, normal to the diamond anvil surfaces with sub-micrometer spatial resolution via time-resolved measurements of variations in the propagation velocity of the acoustic pulse travelling in the compressed sample. It was applied to measure the acoustic velocities in H2O ice up to 84 Gpa. The developed imaging technique provides, for each crystallite (or a group of crystallites) in chemically homogeneous transparent aggregate, usable information on its orientation as well as on the value of the elastic modulus along the direction of the sound propagation. This extends the basis for a successful application of highly developed micromechanical models of solids deformation at mbar pressure. On long term, such experiments extended to earth’s minerals and high or low temperatures would insure a significant progress in understanding of convection of the earth’s mantle and thus evolution of this and other planets.

This diploma work aims to evaluate the functional connection of the cogeneration unit with an internal combustion engine and an absorption heat pump to increase the heating effect of the cogeneration. The aim of this work is to design a functional system and evaluate it from the technical - economic terms. In the introduction of the theoretical work the applied cogeneration technologies used in combined heat and power production are presented. Then there is described the principle of heat pumps, their basic components and theoretical comparison of compression and absorption heat pumps. In the practical part of this work is for a specific application in the area Technická 2 proposed merger of the cogeneration unit with an internal combustion engine and an absorption heat pump, while detailed design parameters used in absorption heat circulation are set. At the end of this paper there are designed various heat exchangers of applied absorption heat pump. The final part of the work is devoted to technical - economic assessment of applied design. In this assestment three different types of heat pumps are compared: Absorption heat pump with working solution H2O-LiBR, absorption heat pump with working fluids NH3-H2O and compressor heat pump.

The thesis is focused on the investigation of fundamental catalytic properties of two model catalysts-CeOx/Cu(111) and CuOx/Cu(111)-by means of advanced surface science techniques. The investigations performed on CeOx are devoted to the study of the relationship between the surface structure and the surface activity of ceria. We develop the preparation method leading to growth of epitaxial CeOx(111) thin films with the adjustable morphological parameters-the step density and the ordering of surface oxygen vacancies. By using the CeOx(111) films with precisely controlled structure we identify the role of the step edges and of the oxygen vacancies in the interaction of water with ceria. The investigation performed on CuOx is focused on the microscopic characterization of the reduction process of Cu2O(111) on the molecular level directly under a near ambient pressure of CO. In direct microscopic study we identify the active initiation centers, the intermediate oxide phases, and the kinetics of the reduction reaction of Cu2O(111).

The solvent-solute interface of a biomolecule is a dynamic but yet highly structured domain that links a chemically diverse solute surface to the chemically homogeneous bulk aqueous phase. The role of the resulting intermediate domain, i.e. the "hydration shell", in regulating DNA structure and recognition has been addressed here by time-resolved infrared spectroscopy. A highly reproducible automated hydration pulse regime was established and implemented for attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy to monitor the structural response of DNA to an incremental growth of its hydration shell on its intrinsic time scale of seconds. The transition from the crystallographically defined BI to the BII substate of B-DNA was found to be driven by the increase of water disorder upon growth of the hydration shell, derived from the water OH-stretching absorption frequency and band width changes. 2D correlation analysis was used to identify different water clusters from the temporal behaviour of their water OH stretching frequencies. The results show that BII-stabilizing structural constraints are exerted by strong water-DNA H-bonds in the grooves of B-DNA and are relieved when the groove-bound water merges into a contiguous hydration shell with the less H-bonded PO2- -solvation sphere at ~14 water molecules per DNA phosphate. The H-bond imbalance at the disjunct hydration sites is split symmetrically around the average H-bond strength of bulk water. Thus, merging into a contiguous hydration shell proceeds at little enthalpic cost and homogeneous connectivity to the outer bulk-like H-bond network, such that alteration in the network distant from the DNA can regulate the BI-BII transition in a cooperative manner. The water connectivity is disrupted by DNA-binding peptides. Remarkably, the data show that the replacement of hydration shell water upon ligand biding is crucial in conferring substate specific recognition by peptides that have little intrinsic structural preference. The antibacterial peptide indolicidin secreted from bovine neutrophils dehydrates the non-PO2--bound hydration sites, thereby rendering the unstructured peptide highly specific for the BI state with vibrational signature almost identical to the bacterial minor groove binder netropsin. The proposed dominant role of hydration shell water for DNA conformation was challenged by studying the competing effect of structured water in the coordination-shell of the lanthanide Eu3+ on water structure in the DNA hydration shell. Whereas no effect is seen at low hydration, a hydrogen-like phase is formed at a stoichiometric ratio of Eu3+ :DNA:H2O of 1:10:140, characterized by a strong increase of the molar volume of hydration water. This novel phase appears attractive for lanthanide and possibly actine separation approaches based on biomolecular coordination.

No description available.