Abstract
The adhesion interaction of an Ir tip with Ir and A1 surfaces has been investigated using the scanning tunneling microscope. Qualitative differences in the adhesion characteristics have been observed. A cluster model based on effective pair potentials has been set up to understand adhesion in atomic-scale contacts. The model calculation provides a semi-quantitative explanation of the experimental data. In particular, it is shown that subtle differences of the atomic-interaction potentials have a significant effect on the contact mechanics. © 1993 IOP Publishing Ltd.