True atomic resolution by atomic force microscopy through repulsive and attractive forces.

The (1014) cleavage plane of calcite has been investigated by atomic force microscopy in water at room temperature. True lateral atomic-scale resolution was achieved; the atomic-scale periodicities as well as the expected relative positions of the atoms within each unit cell were obtained. Along monoatomic step lines, atomic-scale kinks, representing point-like defects, were resolved. Attractive forces on the order of 10(-11) newton acting between single atomic sites on the sample and the front atoms of the tip were directly measured and provided the highest, most reliable resolution on a flat, well-ordered surface.