Spectra of the dications of benzene, naphthalene and azulene

Spectra of the dications of benzene, naphthalene and azulene produced by double photoionisation of the parent compounds are presented. All the electron distributions show evidence of inner-valence Auger processes, which enhance population of low energy states of the dications. It is confirmed that the ground state of the benzene dication is a triplet, contrary to a recent theoretical prediction. The double ionisation energies of the three title molecules are determined as 24.65 ± 0.03, 21.28 ± 0.03 and 20.2 ± 0.2 eV, respectively.