Characterization of Isolated Individual Single-Walled Carbon Nanotube by Electrochemical Scanning Tunneling Microscopy

Abstract

The local density of states (LDOS) of an isolated single-walled carbon nanotube (SWNT) was characterized by electrochemical scanning tunneling microscopy and spectroscopy (EC-STM and EC-STS). Discrimination of individual semiconducting and metallic nanotubes adsorbed on a Au(111) surface was demonstrated by analyzing EC-STS spectra under electrochemical control at a nanometer scale. Two distinct LDOS determined from differential EC-STS spectra are found to be characteristic of the conduction and valence bands, corresponding to van Hove singularities of the SWNT. The absolute potential of the energy level and the band gap between these bands for semiconducting nanotubes could be also evaluated.