Mesoscopic electric field predictions and specimen shape measurements to improve reconstruction in atom probe tomography

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Atom probe tomography is a microscopy and microanalysis technique that can map the distribution of each element in small volume of a material with near-atomic precision. A new facility at Imperial College London is being set up to allow for facile transfer, under controlled atmosphere, of specimens from the atom probe into a transmission electron microscope, allowing for precise imaging of atom probe specimens, which sharp needles below 100 nanometres across. In the analysis of complex devices, typically multilayer stacks, the specimen can develop complex shapes that affect the spatial precision of the data reconstruction. This project will build on a collaboration with the University of Oxford to perform both interrupted atom probe experiments to acquire specimen shapes by electron microscopy and feed these into a mesoscopic model to improve reconstruction protocols, and correlate structure-composition and activity on materials for energy application. We will combine these models with experimental measurements of specimen shape on thin films of materials for energy applications, imaged by transmission-electron microscopy at different stages of the analysis. The developed model is not linked or embedded with the instrument provided by CAMECA, so it will not provide a competitive advance to CAMECA as this is mostly for academic use.