The Electronic Spectra of Aromatic Molecules I: Benzenoid Hydrocarbons

Certain regularities observed in the spectra of benzenoid hydrocarbons by Clar and by Klevens and Platt are interpreted in terms of the 1.c.a.o. molecular orbital theory on the assumption that electron repulsion mixes together only configurations which are degenerate when overlap is neglected. The frequency and intensity relationships between Clar's α, p, β and β' bands find a simple interpretation in this scheme, and the near ultra-violet spectra of benzene, naphthalene and anthracene are interpreted in the light of this theory.