Music of the Spheres at the Atomic Scale

Atomic force microscopy is an established technique for studying surfaces at high resolution, but the surface-tip interaction can also be used to make detailed images of the atoms in the tip. In his Perspective, de Lozanne discusses results reported in the same issue by Hembacher et al., in which the higher harmonics observed in the interaction of a vibrating tungsten tip and a graphite surface were measured. These higher harmonics can be used to improve the spatial resolution of the scanned image, and in particular, allow precise mapping of the tungsten atoms in the tip itself.