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Edge illumination is an X-ray phase contrast imaging technique that allows for the recovery of differential phase and dark-field (also known as scattering) contrast, in addition to conventional attenuation based contrast. These signals are retrieved by analysing the illumination profile of a series of beamlets across a detector. This can provide a wealth of information about the sample, especially biological tissues which produce little contrast using conventional attenuation radiography. To perform signal retrieval, Gaussian curves can be fit to the illumination profiles using a variety of methods. In this work, we compare the most prominent of these methods in terms of their contrast to noise ratio as well as computational times to investigate their effect on the retrieved projection data as well as the final reconstructions.

We present a dynamic implementation of the beam-tracking x-ray imaging method providing absorption, phase, and ultrasmall angle scattering signals with microscopic resolution and high frame rate. We demonstrate the method's ability to capture dynamic processes with 22-ms time resolution by investigating the melting of metals in laser additive manufacturing, which has so far been limited to single-modality synchrotron radiography. The simultaneous availability of three contrast channels enables earlier segmentation of droplets, tracking of powder dynamic, and estimation of unfused powder amounts, demonstrating that the method can provide additional information on melting processes.

Metal coordination complexes represent the chief reusable tools of chemical transformation. Their flexibility and controllability are responsible for the success of numerous fields, from production of feedstock chemicals to medicine to solar energy conversion. Here, several aspects of the behavior of coordination complexes are explored, including the relationship between ligand design and spectroscopic properties. First, the mechanism of vibrational population transfer in trincarbonyl(η4-diene)iron "piano stool" complexes is explored via temperature-dependent 2D-IR spectroscopy and density functional theory (DFT). The "wagging" motion of the carbonyl ligands is characterized, differentiating it from chemical exchange. Second, the structure and energy of hydroxypyridinone-based (HOPO) MRI contrast agents were explored via DFT. This understanding of medicinal metals could allow for directed synthesis of promising future contrast agent candidates. Finally, the dynamics of electronically excited cobalt-zirconium heterobimetallic complexes were investigated with time-resolved IR spectroscopy and DFT. A short-lived singlet metal-to-metal charge transfer state was characterized that mitigated the original goal of the complex: catalytic CO2 reduction chemistry. Together, these experiments expand the knowledge of important coordination complex behavior in ground and excited states.

Edge illumination X-ray phase-contrast imaging makes use of two absorbing masks for precise beam shaping and analysis. As the system is being translated to clinical and industrial environments, a robust quantitative algorithm is required to keep the masks precisely aligned without the need of an expert operator. We present a model for how the illumination on the detector varies as one mask is moved relative to the rest of the system. This model is based on a superposition of known illumination patterns associated with misalignment in each degree of freedom. Through inversion of this model, quantitative estimates of the degree of misalignment can be obtained, and hence can show the position of optimal alignment. The precision of alignment achievable through model inversion was tested, showing at least an order of magnitude improvement when compared to the established mask alignment procedure. Precision of the alignment along the optical axis, and around the three rotational degrees of freedom were found to be [ ± 0 . 78 μ m , ± 0 . 17 mdeg, ± 5 . 08 mdeg, ± 2 . 39 mdeg] respectively, whereas the established procedure would be limited to [ ± 42 . 5 μ m , ± 6 . 69 mdeg, ± 348 mdeg, ± 195 mdeg]. Furthermore, the model allows the decomposition of residuals into random and systematic components, the latter enabling accurate evaluation of imperfections in the masks’ structure which have now become the main limiting factor in the final degree of alignment.