Atom probe tomography has primarily been used for atomic scale characterization of high electrical conductivity materials. A high electrical field applied to needle-shaped specimens evaporates surface atoms, and a time of flight measurement determines each atom's identity. A 2-dimensional detector determines each atom's original position on the specimen. When repeated successively over many surface monolayers, the original specimen can be reconstructed into a 3-dimensional representation. In order to have an accurate 3-D reconstruction of the original, the field required for atomic evaporation must be known a-priori. For many metallic materials, this evaporation field is well characterized, and 3-D reconstructions can be achieved with reasonable accuracy.
Combined Macroscopic, Nanoscopic, and Atomic-Scale Characterization of Gold-Ruthenium Bimetallic Catalysts for Octanol Oxidation