  Recently reported anomalies in the double-photonionization spectra of the
aromatic molecules partially deuterated benzene, naphthalene, anthracene,
pentacene, azulene, phenanthrene, pyrene and coronene are attributed to
Coulomb-pair resonances of pi electrons. The properties of the resonance in
benzene are investigated in detail. The linear behavior in the 2+/1+ ion ratio
above the resonance is attributed to a two-electron transition associated with
excitation from the ground state to a two-electron continuum. A similar
explanation accounts for the linear behavior seen in the pentagonal rings
pyrrole, furan, selenophene and thiophene which do not display resonance peaks.
