Inner-shell charging of multiwalled carbon nanotubes

The electrostatic properties of individual multiwalled carbon nanotubes (MWCNTs) have been investigated from charge injection and electrostatic force microscopy experiments. The MWCNT linear charge densities analyzed as a function of the nanotube diameters are found to differ from classical capacitive predictions by one order of magnitude and correspond to the response of MWCNTs in the external electric field generated at the microscope tip. The fact that MWCNTs can hold an out-of-equilibrium charge is attributed to the inner-shell charging, as a result of the MWCNT finite transverse polarizability and of the intercalation of semiconducting and metallic shells.