Variation of the photodissociation rates with respect to the intensity of the UV field, G₀. The rates are shown for the same molecules as in Fig. 5, following the same color scheme. For the smallest molecule (black curves) the rates scale linearly with G₀ at the range of interest for NGC 7023 (G₀≤ 2600) indicating single photon events occurrence for coronene derivatives. For the larger molecules, multiphoton events are important. Even though H-loss is the dominant dissociation channel, at low G₀ values, H₂-loss can become a competitive process for the larger circumcoronene and circumcircumcoronene species.