EELS modelling of graphitisation

The impact of graphitisation-type processes on the carbon K-edge ELNES is explored for model systems using the CASTEP density functional theory code. For c lattice direction expansion, contraction of spectral peaks occurs between 20 and 27 eV above the edge onset, for a/b lattice dimension expansion spectral peaks are heavily compressed in terms of energy separation and are shifted towards the edge-onset, consistent with a 1/a² relationship. For a nanotube model system, it is shown that for higher curvature, an additional feature was observed in the spectrum ∼5 eV, arguably consistent with 'fullerene'-type character