Physicists have made an atomic force microscope capable of imaging features less than 100 picometers across. The new “higher-harmonic” force microscope uses a single carbon atom as a probe and has a resolution that is at least three times better than that of traditional scanning tunnelling microscopes.

How it works: As the tungsten tip of the probe is made to oscillate at sub-nanometer amplitudes, the interaction between the tip atom and the carbon atom produces higher harmonic components in the underlying sinusoidal wave pattern. Giessibl’s team measured these signals to obtain an ultrahigh resolution image of the tip atom that showed features just 77 picometers (thousandths of a nanometer) across.