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X‐ray ptychography and ptychographic computed tomography have seen a rapid rise since the advent of fourth‐generation synchrotrons with a high degree of coherent radiation. In addition to quantitative multiscale structural analysis, ptychography with spectral capabilities has been developed, allowing for spatial‐localized multiscale structural and spectral information of samples. The SWING beamline of Synchrotron SOLEIL has recently developed a nanoprobe setup where the endstation's first spectral and resonant ptychographic measurements have been successfully conducted. A metallic nickel wire sample was measured using 2D spectral ptychography in XANES mode and resonant ptychographic tomography. From the 2D spectral ptychography measurements, the spectra of the components of the sample's complex‐valued refractive index, δ and β, were extracted, integrated along the sample thickness. By performing resonance ptychographic tomography at two photon energies, 3D maps of the refractive index decrement, δ, were obtained at the Ni K‐edge energy and another energy above the edge. These maps allowed the detection of impurities in the Ni wire. The significance of accounting for the atomic scattering factor is demonstrated in the calculation of electron density near a resonance through the use of the δ values. These results indicate that at the SWING beamline it is possible to conduct state‐of‐the‐art spectral and resonant ptychography experiments using the nanoprobe setup. The first X‐ray spectral ptychography and resonant ptychographic computed tomography experiments at the SWING beamline at Synchrotron SOLEIL are described. To illustrate the application of the techniques, a metallic Ni wire sample is measured.

X‐ray ptychography is a coherent diffraction imaging technique based on acquiring multiple diffraction patterns obtained through the illumination of the sample at different partially overlapping probe positions. The diffraction patterns collected are used to retrieve the complex transmittivity function of the sample and the probe using a phase retrieval algorithm. Absorption or phase contrast images of the sample as well as the real and imaginary parts of the probe function can be obtained. Furthermore, X‐ray ptychography can also provide spectral information of the sample from absorption or phase shift images by capturing multiple ptychographic projections at varying energies around the resonant energy of the element of interest. However, post‐processing of the images is required to extract the spectra. To facilitate this, ProSPyX, a Python package that offers the analysis tools and a graphical user interface required to process spectral ptychography datasets, is presented. Using the PyQt5 Python open‐source module for development and design, the software facilitates extraction of absorption and phase spectral information from spectral ptychographic datasets. It also saves the spectra in file formats compatible with other X‐ray absorption spectroscopy data analysis software tools, streamlining integration into existing spectroscopic data analysis pipelines. To illustrate its capabilities, ProSPyX was applied to process the spectral ptychography dataset recently acquired on a nickel wire at the SWING beamline of the SOLEIL synchrotron. ProSPyXis a Python intuitive graphical user interface that enables extraction of absorption and phase spectral information from spectral ptychographic datasets.

Nannoconus (∼ 5–20 µm) was a major planktonic producer in the Early Cretaceous seas (∼ 150–120 Ma). The heavy calcitic skeletons (micaliths; ∼ 200–1400 picogram) of this extinct nannoplankton genus have contributed to massive carbonate accumulations for over ∼ 30 million years. The micalith microstructure is characterized by an interlocking arrangement of calcitic lamellae spanned around a central canal. The biomineralization process involved in producing the sophisticated micalith is investigated for the first time. Ptychography X-ray computed tomography (PXCT) with synchrotron radiation is applied to an isolated micalith, to obtain a 3D set of tomographic images with ∼ 40 nm spatial resolution. This 3D set was processed to virtually segment the individual calcitic lamella and reconstruct the full micalith through constraining different lengths and angles. The lamellae are repetitively stacked in two distinct inclinations, one following the other, and producing segments combined to form the entire micalith. Individual lamellae were calcified in a “template” of organic layer containing amino acid(s)/biomolecule(s), responsible for creating the interlocking arrangement. Our study of Nannoconus provides a simple yet potent approach to the analysis of biomineralized microstructures characterized by the repetitive arrangement of calcitic units as commonly seen in the calcareous nannoplankton.

Industrial catalysts accelerate chemical reactions in the oil industry, transforming crude oil into finished products such as gasoline, diesel and jet fuel. Understanding the relationships between the structure, chemical composition, properties and functions of catalysts is crucial to reducing the pollution caused by chemical reactions during catalysis. The aim of this thesis is to develop a 3D spectral nano-imaging method to characterize the microstructure of industrial catalysts from the nanometric to the micrometric scale. The method combines X-ray tomography and ptychography with X-ray absorption spectroscopy. It enables the location and chemical state of metals that promote or poison catalysis to be determined. The main challenge lies in reducing data acquisition time, currently around one day for two energy points. The main contribution of the thesis is to develop new methods for faster acquisition without loss of information. This will improve understanding of the relationship between catalyst structure and performance, leading to more efficient and cost-effective developments.