The imaging process in field ion microscopy from the fem to the atom‐probe

Abstract

Abstract A recount of some historical developments may be a useful way of starting the 2nd International Summer Institute in Surface Science. Two years ago, P. H. Emmett opened the 1st Conference with an exciting review of adsorption and catalysis, subjects that have attracted the attention of many investigators over the last 50 years because of the basic importance of the problems and the billion dollar chemical and oil industries in the background. What I hope to illuminate today is a very specialized area of surface science, whose only raison ditre is that field ion microscopy can show us a surface directly in atomic details. The first half of this century of atomic science has passed without offering a means of directly viewing individual atoms as the building blocks of solid matter. Even now, almost 25 years after the introduction of the field ion microscope (FIM), this instrument remains the only device for routinely seeing single atoms as constituents of metal surfaces. We look at the atom as an individual at its specific location; it is no longer merely a well-established concept, more or less convincing by its billionth of a contribution to dim diffraction spot. Besides seeing the atoms within their environment, we can now experiment with single atoms, follow their path, pick one up at wdl, and identify its chemical nature by its atomic weight. For the philosophical value as “Erkenntnis,” field ion microscopy is not a small feat, particularly in view of the basic simplicity of the instrument. Applied in the extended form of an atom-probe FIM, we have a surface-analytical tool 10 orders of magnitude more sensitive than any other. In addition, the extraordinanly high field employed for imaging offers a new experimental parameter in surface physics, permitting finely controlled atom-by-atom “evaporation” of any metal at cryogenic temperature, and a new kind of high-field chemistry. However, these latter subjects, together with the increasingly useful application of field ion microscopy in physical metallurgy for the study of defect structures, shall not concern us in this paper.