The Chemical Structure of a Molecule Resolved by Atomic Force Microscopy

Atomic Imaging Within Adsorbed Molecules

Scanning tunneling microscopy provides atomic resolution images of surfaces and adsorbed atoms, but imaging atoms within an organic molecule adsorbed on a surface is difficult because contrast is lacking in the states that determine the tunneling current. Atomic force microscopy should be able to resolve atoms through changes in short-range chemical forces, but resolution is lost if the scanning tip undergoes modifications or if it moves the molecule. Gross et al. (p. 1110 ) show that in situ functionalization of the tip—for example, with CO—can dramatically improve the resolution of images of pentacene molecules adsorbed on conducting surfaces, like copper, and nonconductors, like NaCl.