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Analyse quantitative des particules atmosphériques par microscopie électronique à balayage couplée à la spectrométrie d'émission X

Abstract : Atmospheric aerosols consist of a complex heterogeneous mixture of particles. Single-particle analysis techniques are known to provide unique information on the size-resolved chemical composition of aerosols. A scanning electron microscope (SEM) combined with a thin-window energy-dispersive X-ray (EDX) detector enables the morphological and elemental analysis of single particles down to 0.1 µm. Automated particle analysis by SEM-EDX raises two practical challenges: accuracy of the particle recognition and reliability of the quantitative analysis, especially for micrometer-sized particles with low atomic number contents. Since low-Z analysis is hampered by the use of traditional polycarbonate membranes, an alternate choice of substrate is a prerequisite. In this work, boron is being studied as a promising material for particle microanalysis. As EDX is generally said to probe a volume of approximately 1 µm3, geometry effects arise from the size of microparticles. These particle geometry effects must be corrected by means of a robust concentration calculation procedure. Conventional quantitative methods developed for bulk samples generate elemental concentrations considerably in error when applied to microparticles. A new methodology for particle microanalysis, combining the use of boron as the substrate material and a reverse Monte Carlo quantitative program, was tested on standard particles ranging from 0.25 to 10 µm. We demonstrate that the quantitative determination of low-Z elements in microparticles is achievable and that highly accurate results (+/-8.8% relative error on average) can be obtained using the methodology described here compared to conventional methods.
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https://tel.archives-ouvertes.fr/tel-00011532
Contributor : Marie Choël <>
Submitted on : Friday, February 3, 2006 - 11:45:16 AM
Last modification on : Tuesday, January 5, 2021 - 3:02:03 PM
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  • HAL Id : tel-00011532, version 1

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Marie Choël. Analyse quantitative des particules atmosphériques par microscopie électronique à balayage couplée à la spectrométrie d'émission X. Océan, Atmosphère. Université du Littoral Côte d'Opale, 2005. Français. ⟨tel-00011532⟩

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