Fluorescence and absorption spectra of 9, 10-diazaphenanthrene solutions at 77°K

The S₁(n, √^*) ? S₀ fluorescence and absorption spectra of 9, 10-diazaphenanthrene solutions in hydrocarbons possess at 77°K a quasilinear structure (Shpolskii effect). In the frozen n-hexane matrix (c = 10^-4 M) the fluorescence spectrum displays a triplet structure (22 181, 22 169 and 22 149 cm^-1 for the O-O transition). The spectra of 9, 10-diazaphenanthrene solution are shifted towards the red compared with those of the single crystal (～ 900 cm^-1). A good agreement between the calculated and experimental values of this shift is obtained. A strong concentration effect on the structure of the spectra is discussed. A quasilinear structure is observed also in the second absorption band.