Tesi sul tema "Spectroscopie par ionisation laser résonante"
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Sifi, Rosa. "Ionisation résonante par faisceaux laser : Application aux sources d'ions et à l'étude de la structure des noyaux radioactifs de tellure". Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00252001.
Testo completoLa naissance du projet ALTO (Accélérateur Linéaire auprès du Tandem d'Orsay) à l'IPN d'Orsay a fait émerger l'idée d'installer une source d'ions laser. A cet effet, une étude de faisabilité a été entreprise avec une installation laser à faible cadence (30 Hz) celle-ci devant être étendue à 20 kHz sur la future installation de faisceaux radioactifs (ALTO). Après un premier faisceau d'étain ionisé avec succès par cette source, nous avons poursuivi l'étude avec un faisceau de cuivre. Nous avons d'abord effectué des tests de schémas d'ionisation du cuivre stable : un schéma vers le continuum et deux schémas vers des états autoionisants voisins. Le schéma le plus efficace commence par une étape d'excitation de longueur d'onde λ1 = 249.2 nm suivie d'une longueur d'onde d'ionisation λ2 = 439.92 nm. Celle-ci correspond à un état autoionisant situé à 62845 cm-1 non connu auparavant et voisin des deux autres états autoionisants sélectionnés au départ. L'efficacité d'ionisation laser avec ce schéma a été mesurée et elle est semblable à celle prédite par la théorie.
L'ionisation résonante par faisceaux laser est également utilisée dans des expériences de spectroscopie auprès de COMPLIS à ISOLDE au CERN. La technique dans ce cas consiste à effectuer un balayage en fréquence autour de la transition d'excitation des atomes pour sonder leur structure hyperfine. Cette étape sera suivie de l'étape d'ionisation pour ioniser les atomes et les détecter. La spectroscopie laser nous permet de déterminer la structure hyperfine et le déplacement isotopique des atomes. Nous avons utilisé cette technique pour étudier les isotopes de tellure sur une longue chaîne isotopique 125m, 127mg, 129mg, 131mg, 132, 133mg, 134, 135 et 136Te. A partir des déplacements isotopiques mesurés nous avons déterminé la variation du rayon carré moyen de charge qui fait apparaître une rupture de pente du rayon de charge à N = 82 : la déformation du noyau diminue jusqu'à N = 82 où elle atteint la sphéricité puis elle augmente au-delà.
La mesure de la structure hyperfine des isotopes impairs de tellure nous a permis de déterminer les constantes de structure hyperfine des isotopes 135 et 133 dans leur état fondamental (Iπ = 7/2- et 3/2+ respectivement) et des isotopes 125, 127, 129, 131 et 133 dans leur état isomérique (Iπ = 11/2-). A partir de ces constantes nous avons extrait les moments nucléaires : µI et Qs. La comparaison des valeurs des moments magnétiques µI expérimentales avec les valeurs de moments existantes dans la littérature mesurées par résonance magnétique nucléaire nous donne un parfait accord.
L'extraction des valeurs des déformations à partir des moments quadrupolaires spectroscopiques en supposant une symétrie axiale conduit à une quasi sphéricité pour tous ces noyaux. Malgré les grandes barres d'erreurs, elles sont semblables aux valeurs des moments quadrupolaires des isotopes d'étain.
Ajayakumar, Anjali. "In gas jet laser spectroscopy optimization for high resolution measurement of actinides". Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMC267.
Testo completoThe Super Separator Spectrometer-Low Energy Branch (S3-LEB) is a low-energy radioactive ion beam experimental setup under commissioning as part of the GANIL-SPIRAL2 facility. In this thesis work, the off-line commissioning of the S3-LEB setup, including first laser spectroscopy measurements in both the gas cell and the supersonic gas jet, the determination of the transport efficiency of laser ions from the gas cell through the RFQ chain, and time-of-flight measurements with the multi-reflection time-of-flight mass spectrometer PILGRIM are discussed. The measurements were performed using erbium, introduced by evaporation from a heated filament in the gas environment. The reported laser spectroscopy results include a characterization of the pressure broadening in the gas cell and proof-of principle isotope shift and hyperfine-structure measurements. This work proves the potential of the setup to conduct the future online tests, where erbium is chosen as the first case for online commissioning. Offline laser ionization and spectroscopy of uranium and americium from the actinide series have been discussed. This thesis work also includes technical developments such as the implementation of the titanium sapphire laser systems and a dedicated entrance window test bench for the S3-LEB. A continuous wave diode-pumped laser system has been built for high-resolution laser spectroscopy application. Americium laser spectroscopy measurements at RISIKO present the potential of such a laser system in performing high-resolution measurements in actinides
Mahjoub, Ahmed. "PROCESSUS ÉNANTIOSÉLÉCTIFS DANS DES COMPLEXES À LIAISONS HYDROGÈNE". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00459590.
Testo completoManuelli, Pascal. "Etude des mécanismes de la désorption : ionisation laser assistée par matrice". Metz, 1995. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1995/Manuelli.Pascal.SMZ9520.pdf.
Testo completoThis report on the mechanisms of matrix assisted laser desorption ionization (MALDI) was realized in mass spectrometry laboratory at Metz'university. This research field appeared in the laboratory after the development of biomolecules analyses by mass spectrometry and the experience stored for fifteen years on "laser desorption". We decomposed the different states of a MALDI experiment for a better understanding of this ionization process. By using some model compounds (as peptides, nucleotides,. . . ) we have studied more precisely the interaction between a laser beam and the different matrices. This allow us to show the great role of small neutral molecules (e. G. Carbone dioxide,. . . ) which are ejected in the plume after the laser pulse. Then, some derivative and complexes of cyclodextrins have been studied. This part is necessary to explain first the interaction between matrix and target molecules and secondly the dependance on the laser wavelength. Thank's to the MALDI technique we can highlight both both structural differences in intact inclusion complexes characterization
Verdun, Francis. "Analyses des hydrocarbures aromatiques polycycliques in situ et étude de l'ionisation en phase solide avec effets de résonance par microsonde laser lamma". Metz, 1985. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1985/Verdun.Francis.SMZ8507.pdf.
Testo completoLengignon, Christophe. "Développement d'un système de mesure de radicaux hydroxyles par spectroscopie d'absorption en cavité résonante hors axe". Phd thesis, Université du Littoral Côte d'Opale, 2012. http://tel.archives-ouvertes.fr/tel-00874400.
Testo completoFerré, Amelie. "Etude des dynamiques moléculaires sondées par générations d'harmoniques d'ordres élevés". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0165/document.
Testo completoHigh harmonic generation (HHG) spectroscopy has proven to be a promisingtool (like probe in pump-probe experiments) in revealing the atomic and molecular dynamicswith the potential for subangstrom spatial resolution and subfemtosecond temporalresolution. Then, rotational dynamics have been resolved on small molecular systems (N2,CO2). This thesis looks to extending HHG spectroscopy methods to probe the structureand the dynamic of complex molecular systems. We will describe the two sources highharmonic generation, the transient grating of excitation and the two-color high harmonicgeneration. We enable to resolve the femtosecond nuclear dynamics in N2O4 and SF6. HHGis also used like a XUV radiation source, playing the role of pump pulse. This approach hasbeen used for the study of photoelectron circular dichroism. An XUV harmonic field witha quasi-circular polarization ionizes chiral molecules. In this manuscript, we will developthis new femtosecond XUV and quasi circular polarization radiation
Henares, González Jose. "Study of condensable ion production by resonant laser ionization". Caen, 2016. http://hal.in2p3.fr/tel-01314260.
Testo completoThis doctoral thesis describes the development of a Resonant Ionization Laser Ion Source (RILIS) at the GANIL facility. The RILIS is a selective ion source technique which is based on a step-wise resonant excitation process where the elements of interest are ionized via atomic resonant excitation by laser radiation. The off-line RILIS test bench at GANIL consists of three tunable titanium:sapphire lasers and a hot-cavity ion source. In this thesis, a new three-step Zn ionization scheme was developed and the already known ionization schemes for Sn have been compared in order to identify the best ionization scheme for titanium:sapphire laser systems. Furthermore, several configurations of the ion source geometry were tested (two diameters and two lengths) in order to provide an optimal ionization efficiency and ion beam emittance. An increasing of the ionizer diameter was found to enhance the production of laser ionizer elements, while no enhancement was observed by modifying the ionizer length. The time-of-flight of the generated ions was also studied for the different ion source configurations at several temperatures. The time-of-flight can provide information about the ion formation inside the ion source cavity. In addition, a technique to measure the convolution of the spatial and energetic spread of the ion bunches at the detection point was developed. Finally, two contamination reduction techniques were studied: Firstly, the ions trajectories through the ion source cavity can be modified by the electric field generated due to resistive heating. Therefore, a study of the appropriate configuration of the electric field direction was performed to reduce the alkali contamination of the ion beam. Secondly, a low work function material was tested in order to reduce the production of alkali contaminants and molecular sidebands generated inside the ion source
Shenar, Nawar. "Spectrométrie de masse par désorption/ionisation laser de peptides modèles : applications en protéomique". Montpellier 2, 2008. http://www.theses.fr/2008MON20150.
Testo completoMasselon, Christophe. "Etude des mécanismes d'ablation-ionisation laser de pesticides adsorbés sur membranes par spectrométrie de masse à transformée de Fourier". Metz, 1997. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1997/Masselon.Christophe.SMZ9712.pdf.
Testo completoLaser desorption/ionisation coupled with Fourier transform mass spectrometry is an ever growing technique with promising applications in the field of surface analysis. However, this method is very sensitive to the experimental parameters. Through this work, after having defined the physical phenomena invoked in the process, we have put the stress on the practical implications of the microscopic processes which have to be taken into account during the analysis. Several examples illustrate this demonstration. The feasability of the method for the analysis of pesticides adsorbed on solid phase extraction membranes has been evaluated for the first time. Five compounds with very different structures and various applications in agriculture have been analysed by classical mass spectrometry and their fragmentation products have been compared to those obtained by laser desorption at 248 nm wavelength. The analysis of the membrane by laser desorption has allowed us to evaluate the possible interferences and the ablation depth at various irradiances. The experiments concerning atrazine and its metabolite have allowed us to propose two distinct ionisation mecanisms : gas phase ionisation versus "true" desorption. Moreover, at the 248 nm wevelength, the various compounds adsorbed on membranes have shown very different behaviors which are better explained by their respective octanol/water partition coefficient than by their absorbance at the laser wavelength. The use of a tripled Nd-YAG laser has allowed the detection of the compounds which couldn't be detected at 248 nm and to confirm the hypothesis of a deeper adsorption of these compounds into the membrane
Martinović, Suzana. "Laser plasma induced ionization of volatile organic compounds : study of the processes and subsequent ion-molecule reactions by Fourier Transform ion cyclotron resonance mass spectrometry". Metz, 1997. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1997/Martinovic.Suzana.SMZ9743.pdf.
Testo completoGas phase ion/molecule reactions between laser produced positive or negative ions and organic molecules were studied by Fourier transform/ion cyclotron resonance/mass spectrometry. Pure metal, metal halide salts and silicone wafer targets were irradiated by laser pulse, and positive and negative ions as well as electrons were formed. Their reactivity towards volatile organic molecules was studied and reaction mechanisms established. Acetophenone were tested as a model molecule for reactions with metal and silicone cations. Reactivities of different cations were correlated to their electronic configuration and promotion energy. Established experimental procedure were applied for ionization and ion-molecule reactions of polyhalogenated molecules. Perfluorotributylamine molecules were left to react with 21 different elemental cations and reaction products and mechanisms were defined. Some other environmental polyhalogenated molecules (dichlorodifluoromethane, halothane and endosulfane) were ionized and detected by the same methods. As complementary ionization method, negative mode ionization (reactions) were studied. Three different ionizing projectiles : laser produced electrons and halide ions as well as fragment halide ions were used to ionize (react with) above mentioned molecules. Electron attachment mechanisms are concurrent to negative ion-molecule reactions
Chety-Gimondo, Rachel. "Étude par ionisation laser couplée à la spectrométrie de masse de films minces d'hydrure d'oxoaluminium et d'oxoborate de gadolinium et de calcium". Metz, 2002. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2002/Chety_Gimondo.Rachel.SMZ0234.pdf.
Testo completoChety-Gimondo, Rachel Muller Jean-François. "Etude par ionisation laser couplée à la spectrométrie de masse de films minces d'hydrure d'oxoaluminium et d'oxoborate de gadolinium et de calcium". Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2002/Chety_Gimondo.Rachel.SMZ0234.pdf.
Testo completoKubler, Benoît. "Etude du processus d'ablation/ionisation laser de fullerènes : préparation et caractérisation de fullerènes spécifiques et de films minces". Metz, 1996. http://www.theses.fr/1996METZ012S.
Testo completoThe aim of this work is to precise the analytical conditions of fullerenes (spheroïdal molecules Cn(n>20)) using laser microprobe mass spectrometry and to optimize laser ablation parameters in order to prepare specific fullerenes (C84, endohedral metallofullerenes i. E. Spheroïdal structures in which a metallic atom is inserted). A potential application of fullerenes has been studied as well : the use of thin C60, C70 and C84 films as new substrates for the CVD (chemical vapor deposition) of diamond. The first chapter is a review presenting some generalities about fullerenes : fullerenes synthesis methods are described with a stress on graphite laser ablation method and various hypothesis on the formation mechanisms of fullerenes are recalled. The second chapter is devoted to experimental techniques concerning, on one hand, the "ex-situ" laser ablation synthesis of fullerenes (in an ablation cell under 500 Torr of argon) and, on the other hand, their caracterization by mass spectrometry. Fullerenes and diamond thin films preparation techniques as well as related caracterization techniques are also described. The third chapter concerns the setting up of a protocol for the analysis of fullerenes by laser microprobe mass spectrometry. This technique is shown to be semi-quantitative in the case of pure fullerenes mixture analysis. The presence of polycyclic aromatic hydrocarbons (PAH) disturbs the repartition of high mass carbon clusters observed on the mass spectra. Finally, the behavior of pure fullerenes has been studied by laser microprobe mass spectrometry under various laser irradiation conditions (wavelength and power density). The recorded clusters distributions allowed us to lay down various hypothesis on the formation mechanisms and structures of high mass carbon clusters Cn (n>100). In the fourth chapter, three points are developped : a method is described for the additionnal production (or recuperation) of fullerenes through a thermal treatment under lightly oxydizing conditions of electric arc soots extraction residues ; a 2% additionnal extraction yield is indeed obtained and the extract is enriched in C84 ; the optimization of the synthesis of yttrium based metallofullerenes by laser ablation of carbon containing compounds (graphite, PAH or extraction residues) mixed with Y2O3 (10% in weight) has lead to the following observations : graphite is the only target material leading to mass spectra showing the presence of metallofullerenes ; it seems not to be any optimal wavelength in the UV-visible domain and a high synthesis temperature (300°C) suggests that Y@Cn and Y2@Cn are not thermically stable. Finally, those compounds are difficult to solubilize ; the role and the effect of fullerenes on the CVD of diamond are described. A morphologicaly heterogeneous C84 deposit increases effectively the size and the density of diamond cristals compared to C60 and C70 deposits. However, the surface topology effects can not be excluded in this case. The results obtained with homogeneous films of pure fullerenes show that the effect of fullerenes can not be separated from the surface state of the underlying silicon substrate (presence of surface defects). Moreover, the studies of fullerenes stability under the diamond CVD conditions recommend a maximal substrate temperature of 550°C
Antoine, Rodolphe. "Etude du caractère plus ou moins conducteur des petits agrégats d'alcalins et d'hydrures de lithium par spectroscopie laser". Lyon 1, 1996. http://www.theses.fr/1996LYO10063.
Testo completoCauchy, Cécilia. "Mécanismes de relaxation de fullerènes photoexcités de l'IR lointain à l'extrême UV : étude par imagerie de vitesse". Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00678808.
Testo completoVigneau, Jean-Nicolas. "Dynamique d'ionisation dissociative du dihydrogène soumis à un champ laser intense". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66574.
Testo completoRuch, David Muller Jean-François. "Etude comparée des matériaux polymériques et/ou polysulfurés par ablation/ionisation laser et bombardement ionique couplés à la spectrométrie de masse. Application à la caractérisation d'élastomères vulcanisés /". Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2002/Ruch.David.SMZ0223.pdf.
Testo completoRuch, David. "Étude comparée des matériaux polymériques et/ou polysulfurés par ablation/ionisation laser et bombardement ionique couplés à la spectrométrie de masse : Application à la caractérisation d'élastomères vulcanisés". Metz, 2002. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2002/Ruch.David.SMZ0223.pdf.
Testo completoQuaglia, Luca. "Etats électroniques des ions moléculaires multichargés transitoires produits par une impulsion laser femtoseconde intense". Paris 11, 2001. http://www.theses.fr/2001PA112336.
Testo completoElectronic states of transient multicharged molecular ions produced by an intense femtosecond laser pulse are studied using different experimental and theoretical techniques. Highly excited states are investigated in the 101̂7 W/cm2̂ laser intensity range with the help of fluorescence spectra of multicharged atomic fragments coming from the molecular explosion. These measures show the existence of highly excited multicharged molecular ions in a straightforward way. The production, efficiency of these highly excited ions strongly depends on the initial electronic configuration. Low excited states studies are based on fragmentation kinetic energy release spectra in the 101̂5-101̂6 W/cm2̂ laser intensity range. These spectra are analyzed with the help of calculations of potential energy curves of multicharged molecular ion electronic states. For the fragmentation of N2 and O2 molecules, the comparison of experimental and theoretical results shows the existence of several low excited states of the corresponding molecular ions and allows to explain the fragmentation energy release of (N2) ̂4+ and (O2)4̂+ ions without resorting to any stretching of the molecule during the multiple ionization process. Population of highly excited states is studied using a two-pulse experimental set-up based on the fragments emission anisotropy. The origin of this anisotropy is experimentally investigated and interpreted with the help of a Thomas-Fermi bidimensional model of the laser-molecule interaction. Pump-probe experiments show that the population of highly excited states is negligible in the 5x101̂5 W/cm2̂ laser intensity range. The fragments emission anisotropy is due to a very fast re-orientation of the molecular system. Theoretical calculations show that re-orientation takes place during the multiple ionization process and Coulomb explosion and gets faster as the laser intensity is increased
Carré, Vincent Muller Jean-François. "Caractérisation par désorption / ionisation laser couplée à la spectrométrie de masse de particules émises par des véhicules diesel Mise en place d'une méthode impliquant la formation de complexes à transfert de charge /". Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2004/Carre.Vincent.SMZ0403.pdf.
Testo completoCarré, Vincent. "Caractérisation par désorption / ionisation laser couplée à la spectrométrie de masse de particules émises par des véhicules diesel : mise en place d'une méthode impliquant la formation de complexes à transfert de charge". Metz, 2003. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2004/Carre.Vincent.SMZ0403.pdf.
Testo completoPolycyclic aromatic hydrocarbons (PAHs) are often associated to complex matrices, as for example exhaust diesel particulate matter (DPM). We choose to use laser desorption/ionization Fourier transform ion resonance cyclotron mass spectrometry (LDI-FTICRMS). The deposit of complexing agent directly on a sampling filter leads to the formation of charge transfer (C-T) with PAHs absorbed on DPM and limits their sublimation during analysis. The laser irradiation at short wavelength (222 nm) and low laser power density (51́06 W. Cm-2) of these so-prepared samples allows PAH molecular ion production to be dramatically increased. This methodology has been applied for the first time to different kinds of particulate matter. These exhaust particles are collected on a standard chassis dynamometer according to the different parts of the new European driving cycle (NEDC) define for light-duty by the economic commission for Europe (urban driving condition with cold start or warm engine, and extra urban driving conditions). The influence of engine temperature, driving conditions and fuel PAH and sulfur contents on PAHs patterns of DPM has been highlighted. Collaboration with the LCSR laboratory (Orléans) was also conducted to investigated model soot particles produced in a shock tube with various precursors representative to the different chemical compounds present in gasoline. Strong correlation between the nature of precursor and the soot particle fingerprint is observed. Soot particles produced by aromatic precursor (toluene) present a specific PAH pattern, which is characterized by a less detection of heavy compounds
Gemayel, Rachel. "Développement et validation d'un spectromètre de masse à ionisation laser pour l'analyse en ligne des nanoparticules dans l'atmosphère". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0241/document.
Testo completoThe aim of this thesis is the development and the validation of an online analytical methodology for continuous measurements of nanoparticles (NPs) in the atmosphere. The particularity of this method is the capacity to determine the size and the chemical composition of each particle simultaneously, what we call mono-particular method. This work was conducted using the instrument LAAP-ToF-MS (Laser Ablation Aerosol Particle - Time of Flight - Mass Spectrometer). Being dedicated for single aerosol measurements, four parts constitute this instrument: aerodynamic lenses are used to introduce aerosols into the instrument, an optical detection system to determine the particles size and synchronize the laser shot used for the ionization process, and the produced ions are then analyzed by a Time of Flight (ToF) analyzer.The work is organized in four parts:The first part consists in the characterization of the LAAP-ToF-MS in order to determine the performances of each of its four parts. The results of this work were published in the international journal "Atmospheric Measurement Techniques".The second part is dedicated to the development of a quantitative analytical method and published in "Talanta" journal.The orientation of the third part is going into the direction of instrumental development to measure NPs not associated to aerosols (Ø<100 nm). Being the first development of this kind using the LAAP-ToF-MS, the work is highlighted by a patent which is under validation.In the end, the last part is dedicated to examples of concrete applications and the usefulness of the LAAP-ToF-MS instrument to study NPs during laboratory experiments as well as for field campaigns
Lourette, Natacha Madeleine Germaine. "Analyse in situ de cellules imprégnées de photosensibilisants par ablation / ionisation laser couplée à la spectrométrie de masse : Application en thérapie photodynamique des cancers". Metz, 2004. http://www.theses.fr/2004METZ036S.
Testo completoThe 5,10,15,20-tetrakis(mesohydroxyphenyl) porphyrin series (m-THPP, m-THPC, and m-THPBC) have attracted interest as possible photosensitizers in PDT owing to their strong absorption in the red region combined with their tumor localizing properties. The m-THPC (FOSCAN, temoporfin), is one of the most efficient prospective sensitizers, although, until recently, there has been little information on the nature of its photoproducts. In aqueous medium, opening studies were carried out by MALDI-TOFMS. After laser irradiation at 650nm, hydroxides and oxides of m-THPC were detected. In addition, m-THPC dehydrogenization into m-THPP was observed. Subsequently, the laser irradiation (647. 5nm) of m-THPP revealed the formation of covalent multimers due to aggregation process. A preliminary structure was proposed. In parallel, a chemical probe (DPBF) was used to characterize the formation of singlet molecular oxygen 1O2 during the period of m-THPC irradiation by MALDI-TOFMS. In both media (ethanol and aqueous), the m-THPC, the DPBF and their respective photoproducts were identified at once. Finally, to understand the photodegradation process in situ, our in vitro assays were performed directly on adherent cells on their culture support. The dye detection inside the whole cells was carried out by MALDI-TOFMS. HT29 human colon carcinoma cells were incubated with m-THPC (2µg/mL). After diode laser irradiation (652nm) of these cells, oxidized photoproducts and m-THPP traces were characterized in situ. Lastly, in an effort to generate proteomic data, three different cancerous cellular lines were analyzed. For each line, a specific protein fingerprint was achieved with reproducibility
Richard, Lucile. "Développements de spectromètres ultrasensibles pour l'analyse de gaz par « optical feedback cavity enhanced absorption spectrocopy » dans le moyen infrarouge avec des lasers à cascades inter-bandes". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY004/document.
Testo completoThis work of these has made it possible to develop and characterize the use of instruments on the "OF-CEAS" technique in the mid-infrared for traces' detection in different mixtures in the gas phase. Inter-band Cascade Laser (ICL) is the latest innovation in semiconductor lasers in this spectral region. Compatibility of ICL with OF-CEAS offers new applications for compact and robust instruments with fast response time and a low detection limit. A demonstration of the good sensitivity and stability of the OF-CEAS instruments was performed with continua absorption measurements (water vapor and nitrogen). But also with the detection of a very low intensity quadrupole line of nitrogen (3x10-29 cm-1/(moléc cm-2). The main objective of this work was to develop an instrument dedicated to nitrogen oxide detection for the analysis of exhaled breath. The analyzer is presented at the sensitivity of 6x10-10 cm-1 in an acquisition of 180 ms. Its limit of detection on NO is at the state of the art, with short term (180 ms) limit of 50 ppt. It reaches the sub-ppt level (0.9 ppt) with 12 min of integration
Salwiński, Aleksander. "Development of novel mass spectrometry-based approaches for searching for low-mass tyrosinase inhibitors in complex mixtures". Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2013/document.
Testo completoThis thesis report presents the development of mass spectrometry-based methods for searching for inhibitors of enzymes in complex mixtures, such as plant extracts. Tyrosinase enzyme was used as the main biological target for the reason of a significant importance of its inhibitors in the cosmetic industry as the skin whitening agents. The first part of this report describes Frontal Affinity Chromatography (FAC), an approach enabling simultaneous ranking the inhibitors within the complex mixture according to their affinities to the biological target. Two hydrophilic capillary-scale polymer-based bioaffinity stationary phases were evaluated in the context of the presence of undesirable nonspecific interactions between the analyte and the solid immobilisation support. In addition, we explored the usability of two types of silica-based particles as a solid support for enzyme immobilisation for FAC. The second part of the thesis manuscript is devoted to Enzyme-coupled Nanoparticle-Assisted Laser Desorption/Ionisation Mass Spectrometry (ENALDI MS) as a low-mass compatible extension of the Intensity ion Fading MALDI MS (IF-MALDI MS) method for high-throughput screening of the inhibitors in the complex mixtures. Two variations of ENALDI MS were evaluated: 'Ion Fading' (IF-ENALDI MS), based on on-the-spot binding of inhibitors by enzyme molecules and 'Ion Hunting' (IH-ENALDI MS), based on selective pre-concentration of inhibitors present in the sample
Yuan, Shuai. "Filamentation induced nonlinear optics". Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25268.
Testo completoFemtosecond laser filamentation, which originates from a dynamic equilibrium between Kerr self-focusing and defocusing by the self-generated plasma produced by multiphoton/tunnel ionization of air molecules, has attracted a lot of scientific applications such as remote sensing of atmospheric pollutants, molecular identification by the alignment of molecules, etc. However, there are many nonlinear processes taking place during filamentation. From the application point of view, it is important to have a good understanding of the detailed physics behind filamentation induced nonlinear optics. Since there are many nonlinear phenomena and applications for filamentation, the thesis only focuses on few aspects of filamentation. Those are: the polarization rotation in atomic/molecular gases, the lasing action of water molecules in air, the humidity calibration through the filament-induced spectroscopy, as well as the fluorescence enhancement by plasma grating. The polarization rotation of an initially linearly polarized probe pulse was studied in atomic/molecular gases. In atomic gases, the ultrafast birefringence induced by Kerr effect was quantitatively measured. In molecular gases, the birefringence and the polarization states of the output probe were modulated at the rotational revival of molecule. We also experimentally investigate the filament-induced fluorescence from the dissociated fragments in air. Fluorescence emissions from OH free radicals at 308.9 nm and NH free radicals at 336.0 nm were observed in air. The backscattered fluorescence from both OH and NH exhibited an exponential increase with increasing filament length, indicating amplified spontaneous emission. We have further investigated the filament-induced fluorescence spectroscopy from a plasma grating. The plasma grating was generated by non-collinearly overlapping temporally synchronized filaments in air. A series of spectral lines from the excited fragments of CN was observed. The fluorescence intensity from CN radicals in plasma grating was much stronger as compared to the case of temporally separated filaments.
Mallah, Khalil. "In depth systemic biology analysis of central nervous system injuries". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1S108/document.
Testo completoIn the context of studying biological alterations occurring post impact to the central nervous system, my thesis was focused on studying the proteomic and lipid changes occurring post injury to the brain and spinal cord. A fundamental spatio-temporal study was conducted on an open-head rat TBI model to identify potential injury-specific markers. Using MALDI MSI, we performed 3D reconstruction of the injured brain at 3 days after injury and depicted lesion-specific m/z lipid molecules. After, MALDI MSI was applied on the acute/sub-acute time frame post impact: 1 day, 3 days, 7 days, and 10 days. In parallel, a microproteomic analysis was carried out on tissue segments directly consecutive to the imaged ones in an approach to correlate both lipid and protein changes. Our results yielded the identification of a family of lipids, acylcarnitines, which are expressed within the injured cortex with maximum intensity 3 days post impact. These lipid molecules also were found to be expressed in the substantia nigra and microproteomics data showed an upregulation in expression of Parkinson’s related proteins. Taken altogether, our results depict a role of link between mild-TBI and Parkinson’s disease as early as 3 days post impact, with a possible role of acylcarnitine. This same family of molecules was also present in SCI. In a therapeutic approach previous results showed RhoA protein as a major candidate post impact in SCI. After using RhoA inhibitor treatment, a proteomic study was carried out to investigate its impact on SCI. The results showed that both in-vivo and in-vitro treatment with RhoA inhibitor stimulated neurite outgrowth and helped in axonal regeneration
Bourgalais, Jérémy. "Cinétique de formation d'agrégats de van der Waals et détection de produits de réactions d'atomes de carbone d'intérêt pour la combustion et les environnements astrophysiques et atmosphériques". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S059/document.
Testo completoThis thesis has been carried out in the team of astrophysics laboratory in the Molecular Physics Department of the Physics Institute of Rennes. In this work, a first part presents the application of the CRESU technique to aggregation of van der Waals clusters of water and propane. We experimentally observed water aggregation on a range of temperatures from 22.9 to 69.4 K, then modeled the early stages of aggregation building on the theoretical determination of rate coefficients. We also made the first measurements of propane dimer formation coefficient over a temperature range of 22.9 to 49.1 K. The second part of this work concerns the detection of the products reactions involving carbon atoms and various molecules (C2H4 , C2H6 , C4H8 and NH3) at room temperature. These studies were conducted at the synchrotron Adavanced Light Source of Berkeley . We also studied the kinetics and products formation of the reaction between carbon atoms and ammonia over a temperature range of 50-296 K. To do this we used the device CRESU of the molecular science institute of Bordeaux. This data was incremented in a dense interstellar cloud model to see their influence on the abundance of nitrogen hydrides. The work of this thesis contribute to better understanding the mechanisms of reactions leading to the formation and growth of molecules and van der Waals clusters in the gas phase in various physical conditions. They provide important data for modeling planetary atmospheres , interstellar clouds and combustion process
Giroux, Karl. "Étude critique de la densité électronique et des températures (excitation et ionisation) d'un plasma d'aluminium induit par laser". Thèse, 2009. http://hdl.handle.net/1866/3813.
Testo completoInterest in the characterization of materials by laser induced plasma spectroscopy (LIPS) is growing with new applications emerging at an ever increasing pace. The purpose of this thesis is to verify the influence of the selection of spectral lines according to measured parameters of the plasma: electron density and excitation (neutral and singly ionized atoms) and ionization temperatures. Our measurements are conducted under typical operating conditions of LIPS: spatially integrated and temporally resolved. We used two binary aluminum targets containing trace elements (Al-Fe and Al-Mg). First, we measured the electron density using Stark broadening of lines from several species (Al II, Fe II, Mg II, Fe I, Mg I, Hα). We observed that the absolute density had a different temporal behavior depending on the species. The ionic lines giving electron densities systematically higher (up to 50 % at 200 ns after plasma ignition), and decreasing faster than densities derived from neutral lines. Densities obtained from trace elements Mg and Fe are lower than densities obtained from the commonly used line Al II at 281.618 nm. In parallel, we studied the space-integrated electron density evolution found from hydrogen Hα line and observed that it has a temporal behavior similar to the density obtained by the Al II line at 281.618 nm. Thus the two species probably share the same spatial distribution within the plasma. Finally, we measured the excitation temperature of iron (neutral and ionized, in trace amount in our targets), and the ionization temperature, using Boltzmann and Saha-Boltzmann plots, respectively. As previously described by Barthélémy et al. (2005), it appears that the different temperatures converge to a single value (considering error bars) after 2-3 microseconds. The different temperatures measured from 0 to 2 microseconds do not overlap, which could be explained by a departure from local thermodynamic equilibrium (Barthélémy et al., 2005), or by considering an inhomogeneous plasma where spatial distribution differs from one species to another, so that high energy species are found from within the plasma’s centre, which is hotter, while the lower energy species are found mainly in the periphery.