Knowledge Bank

The low-energy electronic states of dibenzofuran have been investigated by absorption and emission spectroscopy. The absolute intensity of absorption parallel to the a and b axes of a single crystal at room temperature has been measured from 32 000 to 42 $000cm-1$, and qualitative information about the strength of the c-axis absorption was obtained from a study of finely-ground dibenzofuran compressed in KBr discs. The symmetries of three transitions were determined and tentative assignments of two others were made. The absorption bands in the spectrum of the crystal held at $4.2\circ K$ remained broad, an effect attributed to excitophonon interaction. Spectra of dibenzofuran in a polycrystalline n-heptane matrix at $4.2\circ K$ were sharp and vibrational analyses of fluorescence and phosphorescence are given in terms of the known ground state fundamentals.