Literatura académica sobre el tema "Méthode FLIMM"
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Tesis sobre el tema "Méthode FLIMM"
Pham, Cong Duc. "Cartographie de charges d'espace par méthode FLIMM / Complémentarité avec les méthodes PEA et TPT". Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00452132.
Texto completoPetre, Anca. "Opitimisation de la méthode FLIMM porur la caractérisation en volume des charges d'espace dans les isolants polymères minces". Toulouse 3, 2004. http://www.theses.fr/2004TOU30206.
Texto completoThe aim of the present thesis work is a better knowledge of the space charge distribution in insulating materials, which constitute basic elements of Electrical Engineering systems. Indeed, it is now known that the appearance of local electric fields due to the space charges trapped in material can induce a premature ageing of insulator, and thus a faster breakdown than envisaged. It is then difficult to anticipate the lifespan of a system with time. Thus, several methods of space charge measurement were developed, among which the FLIMM method, a nondestructive thermal technique. The main objective of the thesis was to optimize the FLIMM method, from both experimental and theoretical points of view. Initially, a new measuring cell was proposed in order to increase the precision and the reliability of our experimental measurements. Moreover, the FLIMM current being very weak, a systematic study of the S/N ratio improvement was implemented throughout the acquisition set-up. In a second time, most of the work was dedicated to solve the inverse mathematical problem. Indeed, the results precision strongly depends on it. The numerical resolution of the FLIMM fundamental equation is very sensitive to calculation instabilities. Several deconvolution methods were implemented and compared in order to find the most adapted to our needs. Finally, we carried out a systematic characterization of several polymeric materials (PEN, PET, Teflon). 3-D space charge cartographies were also carried out with a very high lateral resolution on materials irradiated by an electron beam, or submitted to an UV irradiation. This kind of results settles the FLIMM technique among the best investigation methods of located phenomena in insulators
Mendoza, Lopez Duvan Alexander. "Étude des phénomènes de piégeage et dépiégeage de charges par mesures de charge d'espace et de décharge photo-stimulée dans des films polymères minces pour le stockage d'énergie". Electronic Thesis or Diss., Toulouse 3, 2023. http://www.theses.fr/2023TOU30364.
Texto completoWith the development of the polymer film capacitor market, there is growing interest in the study of charge generation, transport and trapping phenomena within relatively thin dielectric films. Indeed, increased requirements imposed by high supply voltages or elevated temperature conditions favor the appearance of charges which, as they migrate through the material, can be trapped to create space charge. This charge trapping dynamic is susceptible to causing localized intensifications of the electric field, thereby engendering electromechanical stresses that may ultimately culminate in material failure. Consequently, it is imperative to investigate the nature and properties of traps found in polymer dielectrics. The aim is to enrich our understanding of these materials and enhance the reliability of the systems in which they are incorporated. Among the available experimental approaches for investigating the electrical behavior of polymers, those capable of providing specific insights into the energy states of traps remain relatively scarce. The most prevalent methods in this regard are probably the Thermally Stimulated Discharge (TSD) and Photo-Stimulated Discharge (PSD) techniques. The PSD method, which entails measuring discharge currents during exposure to light within the UV-visible spectrum, offers the capability to identify interactions between mobile or trapped charges and the energy of incident photons. This approach possesses an advantage over the TSD method, which relies on a temperature ramp, as it does not induce alterations or destruction of traps through thermal effects. However, it is worth noting that interpreting PSD spectra poses challenges, as the measured current may originate from diverse phenomena, including photogeneration of charges or photoinjection of carriers, all of which are likely to interact with the existing traps. In an attempt to elucidate the underlying mechanisms governing in photoinduced current, we propose to couple PSD measurements to space charge measurements. By implementing protocols that systematically manipulate polarization and irradiation parameters, changes in the density or position of charges will serve as valuable indicators of the origin of charges and the kinetics of their trapping and detrapping processes. To achieve this objective, we intend to employ the Light Intensity Modulation Method (LIMM), which is particularly well-suited for the investigation of thin films (with dimensions on the order of a few micrometers) and offers excellent spatial resolution in proximity to interfaces. It will also be an asset for studying electric field reinforcement effects, linked to the use of an interdigitated electrode for PSD measurement. The integration of LIMM and PSD methods within the same experimental setup, and their use in sequential measurement programs, offers the possibility of continuously monitoring trap filling, trap release by light irradiation, and exploring the relationships between applied light energy and trap characteristics. In fact, the measurement system demonstrates in an innovative approach that the reduction in space charge density after PSD measurements is directly attributed to the light disturbance itself, rather than being influenced by concurrent factors such as the time elapsed after the charge period or manipulations leading to charge release
Sauvêtre, Alexandra. "Nouvelle méthode de révélation de traces papillaires par brumisation d'une solution fluorescente". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS406.
Texto completoThe thesis work aims at addressing a particular need of the police and establishing whether it was possible to visualise fingerprints or not by using a revelation process which is able to cover large surfaces. For reaching this goal, we studied in this work a new strategy: the spray deposition of a specifically designed fluorescent dye. The doctoral project consisted first in some preliminary work which aims at creating artificial and reproducible fingerprints. Those fingerprints will be used to compare revealed fingerprints with each other, in order to assess the effectiveness of the new method. The spectroscopic properties of the fluorophore used in this specific material have been studied, so as to have a better understanding of the mechanism taking places during revelation process. We also analysed the means of revelation itself, the spray and its functioning. Indeed, the drops produced by the spray have a fundamental impact on the quality of the fingerprints revealed. The spray and the drops produced have been studied by imaging techniques in order to better understand and try to optimize the revelation process by a substitution of solvent. Lastly, the method proposed has been considered from a technique angle, so as to meet operational challenges of the police on the crime scenes
Déméautis, Claire. "Développement de nouvelles méthodes pour dépasser les limitations rencontrées dans le suivi de biosenseur FRET par microscopie de fluorescence quantitative". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1B035/document.
Texto completoFluorescence microscopy has become an invaluable tool in biology. In particular, it allows to follow in time and space the activity of proteins, using genetically encoded FRET biosensors, in live cell imaging. In my thesis work, I have developed new quantitative fluorescence microscopy methods to overcome the limitations encountered in monitoring FRET biosensors. First, I developed a methodology to monitor simultaneously two genetically encoded FRET biosensors by lifetime measures (FLIM) with a single excitation wavelength. Previously, it was not easy to follow two biochemical activities by FRET biosensors in the same live sample by fluorescence microscopy. Two reasons for that: the existence of spectral bleed through in the detection channel of each fluorescent proteins and the use of two excitation wavelengths for the two donors. By combining two fluorescent proteins pairs: mTFP1 / ShadowG and LSSmOrange / mKate2, the “spectral bleed through” artifact became negligible. It became then possible to follow the kinase activity of PKA and ERK proteins simultaneously by FLIM. Using this methodology, we were able to show an activation of the PKA pathway upon stimulation with EGF. Second, I developed a method to monitor FRET biosensor by fluorescence cross-correlation spectroscopy technique (FCCS). Monitoring the activity of certain proteins may be difficult due to their low expression in living sample and their sub-cellular localization. The FCCS methods requires a low concentration of fluorophores and can therefore be adapted to these samples. FRET has a direct effect on the cross-correlation amplitude when it is measured by following the co-diffusion of two fluorescent proteins attached to a same biosensor. An amplitude ratio decrease, of the autocorrelation curves (green or red) on the amplitude of the cross-correlation curve, corresponds to the presence of FRET. We were able to measure this ratio decreases in cells expressing the FRET biosensor Aurora A wild type (FRET) compared to the K162M mutant one (non-FRET). These first results are very promising to monitor the activity of a weakly expressed protein in living cells biosensor using this approach. The improvement of FRET biosensor monitoring, by quantitative fluorescence microscopy methods presented in this work, will help to answer biological questions of interest requiring the measurement of multiplex FRET monitoring or biosensors at low level expression, where conventional techniques are facing these limitations