Multiple ionization and hydrogen loss from neutral and positively-charged coronene.

In this work, we present a density functional theory study of the structure and stability of neutral and positively-charged coronene C24H12(q+). In particular, we have investigated (i) adiabatic and vertical ionization potentials up to charge q = 9, (ii) the corresponding infrared spectra, and (iii) dissociation energies and potential energy surfaces for several hydrogen loss channels: sequential H+H, H+H(+), H(+)+H, H(+)+H(+), and direct H2 and H2(+). We have found that the stability of positively-charged coronene is extremely high as a consequence of the molecule's capability to redistribute the charge all over the structure. The computed dissociation energies and fragmentation barriers show that there is competition between different hydrogen loss channels and that the relative importance of these channels depends on the charge of the molecule. From a careful analysis of the potential energy surface we conclude that the channel with the lowest barrier corresponds to the loss of H2 from neutral, singly-, doubly-, and triply-charged coronene, H2(+) from quadruply-charged coronene and H(+)+H(+) from quintuply-charged coronene.