Confinement in single walled carbon nanotubes investigated by spectroscopic ellipsometry

Thick films of single walled carbon nanotubes (SWCNTs) with different diameter and chirality distributions are characterized by combining transmission electron microscopy and spectroscopic ellipsometry. The dependence of the dielectric function with the increase of the SWCNT diameter occurs with a drastic redshift of the S11, S22 and M11 transition energies. The transfer integral parameter γ0 of SWCNT is also evaluated and analyzed. We demonstrate that parts of the optical properties of SWCNTs are attributed to a one dimensional confinement effect. •Ellipsometric measurements are performed on carbon nanotube thick films.•The complex dielectric functions of conventional carbon nanotubes are given.•Confinement effects explain the variations of dielectric function of nanotubes.