Investigations of field evaporation with a field-desorption microscope

The self-imaging of monocrystalline point emitters by the field-evaporation of atoms from their surfaces in a desorption microscope produces patterns containing a great deal of unexpected crystallographically-related structure. These patterns are described and characterized for a wide variety of metals, and the influence of temperature and evaporation field are explored. The crystallographic distribution of differently charged ions within the patterns is investigated with an image-forming atom-probe field-ion microscope; the effect of the presence of helium or neon during field-evaporation is noted and shown to significantly affect the relative abundance of the different charge species for tungsten and iridium emitters. It is shown that many of the observed structural details in the desorption patterns can successfully be predicted by treating field-evaporation as involving a prior channelled surface diffusion of the kink-site atoms in directions governed by their near neighbours.