Thesis defense – Said SADEG defended his thesis on the 27th of November 2025

On November 27, 2025, Said SADEG defended his thesis at the Faculty of Science and Technology in Nancy.

Said has been working on his topic since 2021 as part of the GEM team. The title of his thesis is: Micro-XRF and X-ray tomography coupling: advancing towards 3D elemental chemistry

Abstract of his thesis:
Spectroscopic techniques are experiencing considerable growth in Earth sciences due to their ability to provide chemical and structural information at different scales of observation. Among these, hyperspectral micro-XRF (μ-XRF) allows mapping of the elemental composition on the surface, while X-ray computed tomography (XCT) provides information on the internal three-dimensional organization of samples. The complementarity of these two approaches forms the framework for this thesis, whose main objective is to explore the conditions for coupling the μ-XRF signal and the tomographic signal in order to extend the chemical information from the surface to the volume.
To achieve this objective, several methodological challenges were addressed. The first concerned the development of a baseline extraction algorithm capable of processing a complete hyperspectral image (Chapter 3). The second aimed to manage the presence of spurious diffraction peaks: their removal limits artifacts, while evaluating their informative potential for mineralogical identification (Chapter 4). Finally, in Chapter 5, we explored the relationship between the baseline signal and the tomographic signal in order to assess whether the former could serve as a relevant proxy for propagating fluorescence information within the tomographic image.