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Дисертації з теми "Étude spectroscopique. cinétique et mécanistique"
Buffard, Aude. "Synthèse et étude mécanistique de nanocristaux d'InP et formation d'hétérostructures." Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066295.
Повний текст джерелаThis manuscript focuses on the synthesis of InP nanocrystals, their understanding of the mechanisms and the improvement of the optical properties of these objects. The nanocrystals of InP are promising materials for optoelectronic and biomedical applications due to their low toxicity and wide reachable spectral range. However, the synthesis of these nanoparticles is poorly controlled and does not allow to obtain large objects with optical properties comparable to CdSe nanocrystals. The phosphorus precursor commonly used presents a high toxicity and a high cost. The aminophosphine are phosphorus precursors of choice to replace the current one since it has a reduced toxicity and a low cost. A study of different synthesis parameters enabled to highlight the role of some reagents such as primary amines. Through a detailed mechanistic and kinetic study, the understanding of the reactions allows to improve the quality of the synthesized nanocrystals. In order to improve the optical qualities of the synthesized nanocrystals, heterostructures can be formed. InP/ZnS systems allow an increase in fluorescence. However, the deposition material is low. With a view to improve their fluorescence, hybrid heterostructure has been developed. This was developed on nanoplatelets CdSe/CdS as a template. The nanocrystals are surrounded by silica and gold layers which provide good protection concerning the environmental medium. The coupling between the plasmon of the gold and the fluorescence increases the optical properties of the material
Buffard, Aude. "Synthèse et étude mécanistique de nanocristaux d'InP et formation d'hétérostructures." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066295/document.
Повний текст джерелаThis manuscript focuses on the synthesis of InP nanocrystals, their understanding of the mechanisms and the improvement of the optical properties of these objects. The nanocrystals of InP are promising materials for optoelectronic and biomedical applications due to their low toxicity and wide reachable spectral range. However, the synthesis of these nanoparticles is poorly controlled and does not allow to obtain large objects with optical properties comparable to CdSe nanocrystals. The phosphorus precursor commonly used presents a high toxicity and a high cost. The aminophosphine are phosphorus precursors of choice to replace the current one since it has a reduced toxicity and a low cost. A study of different synthesis parameters enabled to highlight the role of some reagents such as primary amines. Through a detailed mechanistic and kinetic study, the understanding of the reactions allows to improve the quality of the synthesized nanocrystals. In order to improve the optical qualities of the synthesized nanocrystals, heterostructures can be formed. InP/ZnS systems allow an increase in fluorescence. However, the deposition material is low. With a view to improve their fluorescence, hybrid heterostructure has been developed. This was developed on nanoplatelets CdSe/CdS as a template. The nanocrystals are surrounded by silica and gold layers which provide good protection concerning the environmental medium. The coupling between the plasmon of the gold and the fluorescence increases the optical properties of the material
El, masri Ahmad. "Étude cinétique et mécanistique de la réactivité des composés organophosphorés avec les photooxydants atmosphériques." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS026/document.
Повний текст джерелаThis thesis establishes the mechanism of heterogeneous degradation of chlorpyrifos (CLP) towards OH-radicals and ozone for CLP on quartz plaques and towards ozone for various contaminations of sand with CLP. The kinetic constants of the heterogeneous degradation are determined in a photo-chemical reactor coupled with a GC/MS. The chlorpyriphos-oxon (CLPO) and the trichloropyridinol (TCP) are the degradation products in the heterogeneous phase for different oxidizer and medium. The heterogeneous reactivity of CLPO towards ozone and OH-radicals are also studied. The results show that the OH-radicals constitute the main pathway of heterogeneous degradation of the CLP and that the CLPO is more persistent than the CLP. The CLPO can be transported far from its point of application. The heterogeneous ozonolysis of the CLP on sand shows that the kinetics are dependent of the contamination in CLP with an exponential behavior.The mechanism established from the analysis of products detected in the condensed phase plans the formation of small organophosphate molecules transferred in the gas phase. We studied the reactivity of two volatile organophosphate molecules the O,O,O-triethylphosphate (TEP) and the O,O-diethylethylphosphonate (DEEP) towards OH-radicals and towards the atomic chlorine in gas phase as a function of the temperature. The TEP and the DEEP present rate constants above 10-10 cm3.molecule-1.s-1. These molecules thus quickly degrade in the atmosphere and are source of a local photochemical pollution.Finally, to complete the degradation pattern of the CLP, its gas phase UV spectra is measured and its constant of photolysis is determined to 1,8 10-5 s-1, involving a photolysis life time of around 16 hours
Rives, Patrick. "Étude spectroscopique et cinétique des mélanges Xe-HCl dans le proche ultraviolet et le visible." Toulouse 3, 1993. http://www.theses.fr/1993TOU30109.
Повний текст джерелаToppi, Stéphanie. "Étude mécanistique et cinétique de la réaction d'hydrodésalkylation d'alkylaromatiques dans les conditions du reformage catalytique." Paris 6, 2002. http://www.theses.fr/2002PA066355.
Повний текст джерелаFakih, Mariam. "Réactivité atmosphérique des principaux produits d'oxydation de première génération des monoterpènes." Electronic Thesis or Diss., Reims, 2024. http://www.theses.fr/2024REIMS010.
Повний текст джерелаMonoterpenes are biogenic volatile organic compounds (BVOCs) widely emitted into the atmosphere by forests and plant crops, thus representing significant players in atmospheric chemistry. Their high reactivity towards atmospheric oxidants has been the subject of several studies in the literature. However, their first-generation oxidation products are less evaluated, and could partly explain the missing reactivity and the underestimation of AOS formation by models. In this context, this study aims to understand the atmospheric reactivity of five VOCBs (nopinone, myrtenal, ketolimonene, caronaldehyde, and limononaldehyde) that are first-generation oxidation products of α- and β-pinene and limonene. This work focuses on the study of degradation processes by determining the kinetics and mechanism of oxidation reactions of the targeted BVOCs by the OH radical, chlorine and ozone, as well as their potential photolysis through the study of their UV-Vis absorption spectra. To this end, the oxidation reactions of five first-generation monoterpene oxidation products were studied in an atmospheric simulation chamber coupled with various analytical techniques (FTIR, SPME-GC/MS, PTR-MS-ToF).The spectroscopic study focused on determining the UV-visible absorption spectra of the five compounds in the 200-400 nm range at a temperature of 353 ± 2 K, and at a pressure below the saturation vapor pressure of COVB. The spectra show a broad absorption band between 240 and 370 nm, corresponding to the n-π* band of the carbonyl group. The significant absorption of these compounds above 290 nm suggests that they are likely to be removed by photolysis in at least a few hours.The temperature kinetic studies carried out in this thesis concern the (VOC+ OH) reaction for nopinone, myrtenal, ketolimonene and limononaldehdye, the (VOC + Cl) reaction for nopinone, myrtenal and ketolimonene and the ozonolysis reaction for ketolimonene, myrtenal and limononaldehyde. Experiments were carried out using either the relative or the absolute kinetic method in the temperature range 298 - 353 K and at atmospheric pressure. The kinetic results obtained made it possible to calculate the atmospheric lifetimes of these compounds. Their atmospheric persistence does not exceed one day. Overall, these lifetimes show that the main route of elimination for the compounds studied is through their reaction with OH radicals, with significant competition in coastal regions from Cl radicals. The study also revealed a generally positive trend for OH radicals and ozone with increasing temperature, and a negative trend for chlorine.Finally, mechanistic ozonolysis studies of ketolimonene, myrtenal and limononaldehyde were carried out. These studies consist of monitoring the temporal evolution of the reagents as well as the reaction product. These data allowed us to extract the formation rate of the products formed during ozonolysis processes. Based on these results, reaction mechanisms of ozonolysis of ketolimonene, myrtenal and limononaldehyde are proposed
Loaiza, Ambuludi Silvia, and Ambuludi Silvia Loaiza. "Étude des propriétés physiques et du comportement mécanique des Basaltes : étude cinétique, mécanistique et toxicologique de l'oxydation dégradante de l'Ibuprofène par l'oxydation avancée électrochimique et photochimique." Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00807532.
Повний текст джерелаLoaiza, Ambuludi Silvia. "Étude des propriétés physiques et du comportement mécanique des Basaltes : étude cinétique, mécanistique et toxicologique de l'oxydation dégradante de l'Ibuprofène par l'oxydation avancée électrochimique et photochimique." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1145/document.
Повний текст джерелаThe first part of this thesis is focused on the remediation of waters contaminated with persistent organic pollutants, in particular pharmaceutical products. Alternative technologies such as the advanced oxidation processes (AOPs), which based on the generation of hydroxyl radicals OH, were applied to the degradation and/or mineralization of a pollutant drug, ibuprofen, in aqueous medium. We chose this pollutant as a model molecule to study due to its large volume of prescription and to its proved presence in the effluents of sewage plants and natural waters. The main objective of this work was the optimization of operational parameters of the applied AOPs. The concentration of H2O2 and Fe2+ reagents ratio to generate hydroxyl radicals for photo-Fenton process, and supporting electrolyte concentration (and the nature) and the applied current for both electro-Fenton and anodic oxidation processes. The oxidation and mineralization kinetics of the ibuprofen were studied and the absolute rate constant for the oxidative degradation of ibuprofen was determined by the competition kinetic method, being 3,84 109 M-1s-1. Toxicity tests of the drug solutions during the anodic oxidation process were carried out by the Microtox method. Our results show that these methods are effective for the degradation of this pharmaceutical product from water. Ibuprofen was completely degraded and the organic matter was almost completely mineralized after the application of these processes. The second part of the thesis includes an experimental study of the physical properties (at different scales) and the mechanical behavior of basaltic rocks. We studied the mechanical behavior and the failure modes of a porous basalt from Azores. Results were acquired under triaxial compression experiments on water saturated samples at room temperature. This basalt presented two modes of deformation. At low confining pressure, the samples exhibited a brittle mechanical behavior and a localized deformation (shear band). For higher confining pressure, this basalt showed a ductile behavior and localized compactions (compaction bands). The mechanical data allows us to plot the full yield surface for the porous basalt. The quantification of the physical properties of two types of basalts from the Galapagos was performed at room temperature and pressure. In order to study the effect of cracking on the physical properties of these basalts, samples were subjected to thermal treatments to induce thermal crack damage. Finally for the less porous basalt, measures of wave velocities under the pressure at which it is subjected in depth were acquired. The obtained results and the following application of models with them allow quantifying the density of initial cracks and of those induced by thermal treatments, as well as quantifying the aspect ratio of cracks. The studied physical properties led to better understand the role of the pore network of the rock in these physical properties. This laboratory study was necessary for the interpretation of data collected in situ by seismic refraction method
Pantazidis, Amalia. "Déshydrogénation oxydante du propane sur catalyseurs VMgO : optimisation du solide, étude mécanistique et cinétique, application en réacteur à membrane." Lyon 1, 1996. http://www.theses.fr/1996LYO10229.
Повний текст джерелаEl-rachidi, Mariam. "Étude cinétique et mécanistique des réactions hétérogènes du folpel et du dimethomorphe avec l'ozone et les radicaux OH. Photooxydation homogène des composés morpholiniques avec les radicaux OH." Thesis, Reims, 2012. http://www.theses.fr/2012REIMS011.
Повний текст джерелаThe research study discussed in this thesis concerns the determination of the kinetic rate constants of the heterogeneous degradation of pesticides folpet and dimethomorph by ozone and OH-radicals using the technique of a simulation chamber coupled to a GC/MS analytical system. The study also involves the identification of the degradation products of the analyzed compound in the condensed phase using SPME/GC/MS. The heterogeneous OH and O3-reactivities of the identified degradation product of dimethomorph, (4-chlorophenyl)(3,4-dimethoxyphenyl)methanone (CPMPM), are also evaluated experimentally. The obtained results show that the rate constant values of the analytes are in the order of 10-20-10-19 and 10-14-10-12 cm3.molecule-1.s-1 relative to heterogeneous O3 and OH-oxidation, respectively. Such values implicate tropospheric life-times that vary from a few days to several months, meaning that these compounds are relatively persistent and may be transported to regions far from their point of application.The UV-absorption spectra and homogeneous OH-reactivities of the expected degradation product of dimethomorph in the gas phase, N-formylmorpholine (NFM), and two other gaseous compounds, morpholine and N-acetylmorpholne (NAM) are also studied. The results show that these compounds are not susceptible to photolysis in the atmosphere and that they exhibit strong reactivity towards OH-radicals. Generally speaking, their atmospheric life-times are in the order of a few hours and thus they are non-persistent