Multi-element tomography: leveraging absorption and phase contrast in soft x-ray ptychography

X-ray ptychography enables high-resolution imaging of multi-element systems by providing both optical density and phase contrast images. This study integrates few-energy ptychography with computed tomography to distinguish and spatially resolve nickel nanoparticles within a porous Al₂O₃ support. By leveraging contrast differences near a given absorption edge, our method achieves unambiguous 3D identification of an element using a single energy, significantly reducing acquisition time while maintaining nanoscale resolution. This approach is particularly valuable for studying catalytic processes, such as nanoparticle exsolution and dissolution in mesoporous alumina. High-resolution 3D imaging of these structures advances our understanding of catalytic dynamics, with implications for optimizing materials in environmental applications like dry reforming methane.