Computing C1s X-ray Absorption for Single-Walled Carbon Nanotubes with Distinct Electronic Type

The experimental data recorded for the C1s edge in X-ray absorption spectroscopy for graphite, graphene and nanotubes, have consistently exhibited certain discrepancies when compared with theoretical calculations. A theoretical approach to estimate the energy scale normalization for the C1s shape in X-ray absorption is presented within the time dependent density functional theory and random phase approximation framework employing the loss function. The position of the sigma* resonance is fairly localized whereas core hole effects must be envisaged in order to have an agreement with the delocalization of the pi* resonance, which is displaced by similar to 2 eV. Here we report a combined experimental and theoretical approach to identify the electronic conduction band of single walled carbon nanotubes using X-ray absorption, taking into account their metallic character.