Fractional contribution from coronene (top panels), circumcoronene (middle panels) and circumcircumcoronene (bottom panels) derivatives for different G₀ and n(H) values. The contributions include all ionization states. The left column shows the contribution from the completely dehydrogenated molecules, C₂₄, C₅₄ and C₉₆; the middle column shows the fraction of the normally hydrogenated molecules; and the right column shows the distribution of the superhydrogenated species. In all cases, we have assumed a fraction of molecular hydrogen of 0.5, and a carbon abundance of 3.5 × 10^-4 relative to hydrogen. Black lines represent constant G₀/n(H) ratios and are given as a reference.