Anisotropy in the X-ray absorption of vertically aligned single wall carbon nanotubes

Carbon nanotubes are archetypical one dimensional systems, with peculiar anisotropic electronic properties. Only recently μm thick films of vertically aligned SWNT became available. The vertical alignment of the nanotube mats allows the realization of scattering geometries promoting specific dipole transitions parallel and normal to the axis of the SWNT. We find well expressed mosaic spreads for the π* and σ* resonances. Full three dimensional modelling of the dipole transitions as well as of the alignment demonstrate polarization dependent X-ray absorption to be an accurate, versatile non destructive and reliable tool to quantify the alignment of SWNT on a bulk scale.