Material contrast by combined scanning tunneling and force microscopy imaging of single-walled carbon nanotubes

A newly developed combination of tunneling and force microscopy enables near-atomic point resolution, and tubes can be identified without the need of a conducting substrate. This is a crucial step for the characterization of electronic devices based on individual single-wall tubes. Images of the spatial current distribution taken in constant force mode show strongly enhanced contrast between tubes and gold or silicon dioxide substrates, respectively, which is attributed to the unusual elastic properties of the nanotubes.