Item – Theses Canada

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OCLC number
46501864
Author
Tremblay, Sébastien,1969-
Title
Optimisation de paramètres expérimentaux et analytiques en imagerie par spectrométrie des pertes d'énergie des électrons transmis
Degree
Thèse (M. Sc. A.)--École Polytechnique de Montréal, 1995.
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, 1996.
Description
3 microfiches
Notes
Comprend des références bibliographiques
Abstract
An electron energy loss spectrum analyser was programmed for the XWindows environment to permit the development, testing and optimization of quantification algorithms. This software also permits the mapping of analysis results (such as the thickness, the atomic concentration of an element and the plasmon energy) by using a spectrum image (spectra acquired sequentially on a sample scanned by the electron probe in a transmission electron microscope (STEM)). With this software, it was possible to map the plasmon energy for thin foils of AA3004. This operation resulted in a chemical enhancement of contrast of precipitates ($\alpha$-Al(MnFe)Si or Al$\sb6$(MnFe)) embedded in the aluminium matrix. The volume fraction $f\sb{V}$, of those precipitates was assessed with three methods (of which two use plasmon energy maps and the other uses bright field STEM images) for three AA3004 sheets with slightly different compositions and submitted to different heat treatments. The $f\sb{V}$ values ranged from 0,8% to 2,4% depending on the sample and the method applied. Possible quantification errors were studied for the three methods. Particular attention was devoted to the plasmon energy quantification algorithm as well as to the thickness measurement and mapping (needed by two methods) obtainable with EELS analysis. In the process, many spectrum image acquisition parameters were studied to optimize subsequent operations and to correct for artifacts. Parameter selection rules were established to relate the maximum admissible (intermediate or final) error with the inherent limits of the microscope/spectrometer assembly and with the expected morphology of the analyzed microstructures in the thin foil.
ISBN
0612082288
9780612082281