POLARIZED ABSORPTION SPECTRA OF FLUORENE SINGLE CRYSTAL

Polarized absorption spectra of a very thin fluorene crystal (0·1 μm -0·2 μm) have been studied. From the polarized absorption spectra it has been found that the ratio of the intensity of absorption along the b axis to that along the a axis of the crystal is nearly equal to 1·63 for the first system and 1·40 for the second system of transition. As these results roughly agree with the oriented gas model value for the short-axis transition, one may be inclined to suggest that the transition is along the short axis of the molecule. But, from further consideration of the molecular orientation and particularly of the absorption coefficient data, the authors suggest that the transition is mostly along the long axis of the molecule, with a weak short-axis contribution.