Wandering surface atoms and the field ion microscope

Interest in information about individual atoms on crystal surfaces has been strong since the early 1930s. By then it had become clear that to understand technologically important surface phenomena such as crystal and thin‐film growth, heterogeneous catalysis, sintering and surface oxidation, it was necessary to understand atomic processes at crystal surfaces. In response to this need for qualitative and quantitative knowledge physicists and chemists developed detailed models of atomic activity on crystal surfaces. However, for many decades there was no way to confront speculation with actual data on atomic behavior—that would require observations of individual atoms. No less a capability is now available (see figure 1) through the use of the field ion microscope. As we will see, observations of individual atoms have not only provided much interesting information on surfaces but they have also become surprisingly routine.