Comparison of the energy probability distribution G(E) obtained from MC simulation (Herbig star model, 7.5 AU, (C₉₆H₂₄)₂) with photodissociation (blue) and without photodissociation (orange). Additionally, the probability for photodissociation (green, dotted) and IR-cooling (green, dashed) are shown. With photodissociation, PAHs cool down so efficiently that only a smallfraction of time is spent at high temperatures.