The cross-section per carbon atom, σ_C (in Mb per C atom, 1 Mb  = 10^-18 cm²), for the optEC_(s) model (smooth curves peaking at  ~14 eV, for the extreme and three intermediate E_g cases), compared to laboratory data and other models. The vertical dot-dashed lines mark the band centres of the π − π^∗, C₆ and σ − σ^∗ bands at 4.0, 6.5 and 13 eV, respectively. The diamond (purple and violet lines) and graphite data (black) are shown for comparison.