Search results for "Infrarouge"
showing 10 items of 36 documents
Tellurites fibers for infrared supercontinuum sources : opto-geometric profiles and extrinsic absorptions management
2016
This PhD thesis work focuses on the synthesis and purification of vitreous materials used for the development of waveguides with varied profiles, dedicated to supercontinuum (SC) generation between 1 and 5 μm.Concerning the purification of tellurite glasses, several leads were followed, but best results are obtained for the purification of the TeO2-ZnO-Na2O glassy system by the means of zinc fluoride. Attenuation measurements performed on several meter-long single-index fiber samples reveal the nearly complete elimination of water-related absorptions between 3 and 4 μm (OH ions concentration lower than 1 ppm mass.). Such water-purified glasses were firstly dedicated to microstructured optic…
Contribution and limitation of infrared spectroscopy technique to understand physisorption processes on MFI zeolites
2011
This manuscript is devoted to the study of adsorption processes by FTIR spectroscopy. The experimental results concern the adsorption of ethylene, trichloroethylene, tetrachloroethylene, sulfur hexafluoride or p-xylene on MFI zeolites, more especially on silicalite-1. The first step of the work was to develop a new experimental device and procedure in order to obtain reliable absorption infrared data and to improve results previously obtained by a prototype. The first main result is to characterize, maybe for the first time, the evolution of the spectrum of the adsorbent all during the adsorption process. Experiments reveal that the zeolite infrared spectrum undergoes strong modifications w…
Infrared spectroscopic study of beta-lactoglobulin interactions with flavor compounds
1999
International audience
Mid-infrared supercontinuum generation in chalcogenide and telluride fibers for sensor devices
2019
This thesis reports on the progress made during my PhD concerning supercontinuum generation and its application in two types of materials: chalcogenide and tellurite glasses. Concerning the chalcogenide axis, two new arsenic-free compositions are developed: Ge20Se60Te20 and Ge20Se70Te10. Thermal and optical properties of these two glasses are studied and two types of fibers are manufactured: a step-index fiber and a suspended core fiber. The generation of supercontinuum in these two fibres, pumped by an optical parametric amplifier, gives competitive results compared to the current state of the art of supercontinuum generation in chalcogenide fibres. Supercontinuums widening between 2 and 1…
Sources optiques infrarouges impulsionnelles ultra-courtes et spectralement ultra-larges générées par effet Raman dans les fibres creuses
2019
Gas-filled Hollow-Core Photonic Crystal Fibers (HC-PCF) are efficient tools regarding ultra-wide and coherent optical frequency combs by Stimulated Raman Scattering (SRS). Coherence is reached thanks to highly transient regime as it allows amplification, from quantum to macroscopic level, of a unique spatial and temporal mode (TSM). This results in the generation of Stokes waves with a well-determined phase. The present work details on which time scale coherence can subsist, between two consecutive pulses. The possibility of making a new kind of mode-lock is studied. Then the extreme versatility of gas-filled HC-PCF is illustrated by presenting different kind of new laser sources, exploitin…
Study of the hydrolysis of lithium hydride
2015
The hydrolysis of LiH at room temperature and under low water vapor pressure (PH2O < 10 hPa) is investigated by thermogravimetry and FTIR spectroscopy with low sample mass. Then, to be closer to industrial conditions, hydrolysis of LiH is studied by manometry either in closed (adjustable PH2O) or open (constant PH2O) system using larger amounts of sample and heavy water. Products of the reaction are characterized by X-ray diffraction and FTIR spectroscopy. The first set of experiments show that the mechanism of hydrolysis starts with the formation of lithium oxide Li2O. Then, when the oxide layer is sufficiently thick, the hydrolysis reaction is followed by the formation of lithium hydroxid…
Etude des sources supercontinuum à fibres transparentes dans le moyen infrarouge
2012
The work reported in this thesis deals with the study of the supercontinuum generation in fibers transparent in the mid-infrared. To generate a supercontinuum between 3 and 5 µm we compare different glass families such as fluoride glasses, tellurite glasses and chalcogenide glasses. These fibers are pumped with fiber lasers emitting at 2 µm with nanosecond or picosecond pulse duration. This wavelength allows us to reach the zero dispersion wavelength of the chalcogenide tapered fibers. We report supercontinuum generation up to 3800 nm in a fluoride glass fiber. A connection with 75 % of transmission is made between a ZBLAN and a SiO2 fiber. We also measured absorption lines of the methane a…
Influence de la symétrie et de la taille de la molécule adsorbée sur le processus d'adsorption des composés éthyléniques sur une zéolithe de topologi…
2005
This manuscript lies within the scope of the understanding of the stepped isotherm observed during adsorption, on MFI zeolites, of some organic compounds which have a similar size to that of the pore opening of zeolite. During this work, the process of adsorption of ethylene and tetramethylethylene is initially studied by gravimetry and then by in situ infrared spectroscopy. This last technique enables to follow simultaneously the modifications of the adsorbent and the adsorbate. The analysis of these data lets suppose that the step in adsorption isotherm can be explained by taking account simultaneously of the symmetry and the size of the admolecule. In addition to the infrared bands chara…
Identification of markers that can be recognised using spectroscopic sensors and which reflect key stages in the cooking of meat and fish
2016
One of the purposes of the Opticook project is to install spectroscopic sensors in ovens, so equipping them with non intrusive tools allowing following cooking process of meat and fish. The hypothesis on which sensors were developed was: are muscular proteins proper probes to discriminate among several cooking degrees? Thus, at the beginning of the project several tools were used to characterise effect of several cooking degrees on macroscopic properties (texture and colour) of beef, chicken and cod fillet samples. Following, calorimetry and spectroscopic techniques were used to study transformations at molecular scale. In particular, visible spectroscopy followed denaturation of haemprotei…
UV resistance of Bacillus subtilis spores - Involvement of DPA and characterization by photonic microscopy
2022
The aim of this project was to study the UVc resistance of Bacillus subtilis spores. The first part of this project focused on the dipicolinic acid molecule (DPA) which is known to be involved in the UV resistance of spores. However, some points remain unresolved. In particular, it is known that this molecule forms fluorescent photoproducts (DPAp), which were not identified at the beginning of this project. No information concerning the role of these DPAp in UVC resistance was available at that time. During this project, a protocol was established to follow the appearance of these photoproducts directly inside the spore core. A method was also set up to artificially introduce DPAp into the …