EXPERIMENTAL AND THEORETICAL-STUDIES OF THE ELECTRONIC-SPECTRA OF DIHYDROXYNAPHTHALENE RADICAL CATIONS IN BORIC-ACID GLASS

The electronic absorption spectra of 1,5-, 1,6- and 1,7-dihydroxynaphthalene radical cations have been studied experimentally as well as theoretically. Radical cations were produced by photo-oxidation in boric acid glass at room temperature, and their electronic absorption spectra were measured in the 190-900 nm region. A systematic study of the effect of irradiation time and solute concentration on the spectra was made. The electronic transition energies of the cations were calculated using the Longuet-Higgins-Pople and Wasilewski methods with limited configuration interaction. The transition energies were inferred from photo-electron spectra of the parent molecules. The correspondence between observed and calculated results was found to be good. A relation between the para (p) band of the molecules and the "A" band of their radical cations was established.