Single-shell carbon nanotubes imaged by atomic force microscopy.

Single-shell carbon nanotubes, approximately 1 nm in diameter, have been imaged for the first time by atomic force microscopy operating in both the contact and tapping modes. For the contact mode, the height of the imaged nanotubes has been calibrated using the atomic steps of the silicon substrate on which the nanotubes were deposited. For the tapping mode, the calibration was performed using an industry-standard grating. The paper discusses substrate and sample preparation methods for the characterization by scanning probe microscopy of nanotubes deposited on a substrate.