Electronic Transitions of Some Polyacene Mononegative and Dinegative Ions

Abstract
Absorption spectra of the pentacene mono and dinegative ions in the 5–42 kK region were measured. To determine the relative directions of polarization of the electronic transitions a glassy solution of the dinegative ion was photo-oxidized with plane-polarized ultraviolet light and extinctions of this dichroic solution were measured for plane-polarized light parallel and perpendicular to the vector of the photo-oxidizing light. The experimental spectra are compared with those of the mono and dinegative ions of some other polyacenes. A qualitative interpretation of the spectra is given.