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Electron-excited Auger-electron coincidence spectroscopy off solid surfaces
Doctoral Thesis   Open access

Electron-excited Auger-electron coincidence spectroscopy off solid surfaces

Billy Dean Todd
Doctor of Philosophy (PhD), Murdoch University
1989
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Abstract

An experimental and theoretical investigation has been conducted in an attempt to perform electron-excited coincidence Auger-electron spectroscopy off solid surfaces. The experimental apparatus was designed and built to achieve time and energy resolutions of ~2ns and ~l-2eV respectively. The entire experimental system was shown to have functioned as designed. Experiments measuring the Auger electron in coincidence with its ionizing (core-loss) electron were attempted on samples of amorphous silicon and iron sulphide with negative results. The measurements placed upper bounds on the coincidence trues-to-accidentals ratio of 0.09 and 0.02 for silicon and iron sulphide respectively. A comprehensive theoretical model was developed to calculate the expected true coincidence count rate as well as the trues-to-accidentals ratio for silicon. The model predicts that the true coincidence count rate and trues-to-accidentals ratio are several orders of magnitude too low for the experiment to be feasible with the existing experimental apparatus. It demonstrates that the main problem is the high value of the secondary electron background which increases the accidental coincidence background rate to an unacceptable level. For completeness the model was further modified and applied to the Auger-photoelectron coincidence experiment performed by Haak et al [1978,1984] and predicts the feasibility of this experiment. Finally, suggestions for future electron-excited Auger-electron coincidence experiments are provided with the aim of achieving successful coincidence measurements off solid surfaces.

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