SEEING ATOMS - THE ORIGINS OF LOCAL CONTRAST IN FIELD-ION IMAGES

This article reviews the theory of local contrast in field-ion images, as it has developed over the last 15-20 years. The issue has been: How do we see atoms? The question has partly been whether contrast formation is dominated by a rate-constant or by a gas-concentration mechanism. But there has also been difficulty in establishing any satisfactory numerical explanation of the long-known resolving power of the field-ion microscope. Although much numerical modeling remains to be done, it is now possible to give a coherent, quantitatively justifiable, physical explanation of how the field-ion microscope works: we now know how men first saw atoms. The review is divided into four parts, covering: background theory; developments until the end of 1982; recent progress; and discussion of its consequences.