Dichroism of Dyes in the Stretched PV A Sheet. III. Direction of Absorption of Pinacyanol Iodide

Abstract 1. Dichroism of pinacyanol iodide in the PVA sheet was observed in the region higher than 220 mμ, and at least sixteen absorption bands were recognized. 2. The relation of Rd to Rs was analyzed concerning some absorption bands, and it was verified that there are two groups of transitions, one existing along the long axis of the molecule, the other being at right angles to one another in geometry. 3. The absorption group at right angles to one another appears in the shorter wavelength region than about 340 mμ, and it was shown that this is due to the two orthogonal electronic transitions localized in the quinoline nuclei of the molecule. 4. The absorptions of the long axis of the pinacyanol molecule consist of two groups, each involving several bands and it was pointed out that the bands are distributed with nearly constant distance of 1500 cm−1 between adjacent one. 5. It was deduced that the molecule is not a planar and both quinoline planes are far from planar. 6. Sixteen absorptions mentioned above were reasonably classified in their relation to the transition direction or in their correspondence to the molecular structure.