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ANALYSES ET COMPORTEMENTS DES PARTICULES CREEES DANS UN PLASMA RADIOFREQUENCE BASSE PRESSION EN MELANGE METHANE/AZOTE.

Abstract : In this work, the generation and characterization of particles in methane and methane-nitrogen radiofrequency discharges have been studied in order to understand the effect of nitrogen incorporation within the gas mixture onto the formation and the chemical structure of the carbonaceous particles. We have also analyzed the nitrogen effect of the particle behaviour on the electric characteristics of plasma. Whereas the incorporation of a small quantity of nitrogen within a methane plasma delays the particle formation without modifying their behaviour within the discharge, a greater incorporation of nitrogen ([N2]>30%) enhances the particle synthesis, modifies their behaviour within the discharge and leads to a multi-generation phenomenon for nitrogen-rich plasmas ([N2]>70%). For a particular gas mixture of 30% CH4 / 70% N2, we also put in evidence the presence of macroscopic instabilities corresponding to a phenomenon of electrostatic interactions between the two particle clouds at the cathodic and anodic sheath boundaries. These phenomena of multi-generations and instabilities were correlated with the variations of the electric characteristics of the discharge. Various characterization methods (SEM, FTIR, XPS, EDAX) are used to evidence the size modifications, the morphology and the chemical composition of the particles. These analyses show the emergence of nitrogenized bonds CN (simple, double and triple) and NH ones. For 10% CH4 / 90% N2 mixtures, we measured a N/C ratio close to 0,5. The increase of the nitrogen percentage also involves a graphitization of the particle chemical structure.
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Submitted on : Friday, January 15, 2010 - 11:30:14 AM
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  • HAL Id : tel-00447521, version 1

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Jérémy Pereira. ANALYSES ET COMPORTEMENTS DES PARTICULES CREEES DANS UN PLASMA RADIOFREQUENCE BASSE PRESSION EN MELANGE METHANE/AZOTE.. Physique [physics]. Université d'Orléans, 2007. Français. ⟨tel-00447521⟩

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