Absorption spectra of dimer cations. Part 3.—Naphthalene and anthracene derivatives and pyrene

The absorption spectra of γ-irradiated solutions of naphthalene in glasses at 77 K provide further evidence for the existence of dimer cations (C10H8)+2. Results are also presented for several methyl-naphthalenes, pyrene and 1,2-di(1-naphthyl)-ethane in which a weak intra-molecular interaction occurs. Attempts at producing a dimer anion were unsuccessful. Dimer cations of 9-methyl- and 9-bromo-anthrancene were produced by radiolysis of dilute solutions of the di-anthracenes; there appear to be two distinct dimers in this case.