Electronic spectra of alternant hydrocarbon di-negative ions

Abstract

The electronic spectra of the di-negative ions of anthracene, tetracene, perylene, terphenyl and quaterphenyl have been interpreted qualitatively, using the Hfickel one-electron treatment and a correction for the correlation between the electrons which in the excited states move in broken shells. In this way the locations of the absorption bands in the visible and near ultraviolet could be satisfactorily predicted. The agreement between calculated and observed dipole strengths is not as good. On the average the calculated dipole strengths are twice to three times as high as the experimental values. For qualitative interpretations, however, the present treatment seems adequate.