Origin of High-Density Zone Lines in Field Desorption Patterns of Tungsten

Among the characterization techniques which allow us to "see" single atoms, field ion microscopy (FIM) and atom probe tomography (APT) are unique in the way that individual atoms, instead of a collection of atoms, can be imaged. At the same time, data collected by these techniques can provide three-dimensional information of atomic structures via reconstruction. Our ability to reconstruct three dimensional atomic structures however relies on our understanding of the signals. In these techniques, individual or molecular species are field-evaporated from a sharp needle shaped specimen under an intense electric field and fly towards a 2D detector where their impact is recorded. In APT, the collective impacts form a "field desorption pattern" revealing the crystallographic structure of the specimen. While the patterns reveal the crystallography and atomic arrangement with unique resolution, they are not free of artefacts.